New paleomagnetic studies of Cretaceous and Miocene rocks from Jinggu, western Yunnan, China: Evidence for internal deformation of the Lanping–Simao Terrane

Accepted Manuscript Title: New paleomagnetic studies of Cretaceous and Miocene rocks from Jinggu, western Yunnan, China: evidence for internal deformation of the Lanping–Simao Terrane Author: Liang Gao Zhenyu Yang Yabo Tong Heng Wang Chunzhi An PII: DOI: Reference:

S0264-3707(15)00064-2 http://dx.doi.org/doi:10.1016/j.jog.2015.06.004 GEOD 1370

To appear in:

Journal of Geodynamics

Received date: Revised date: Accepted date:

14-11-2014 12-6-2015 12-6-2015

Please cite this article as: Gao, L., Yang, Z., Tong, Y., Wang, H., An, C.,New paleomagnetic studies of Cretaceous and Miocene rocks from Jinggu, western Yunnan, China: evidence for internal deformation of the LanpingndashSimao Terrane, Journal of Geodynamics (2015), http://dx.doi.org/10.1016/j.jog.2015.06.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ip t

New paleomagnetic studies of Cretaceous and Miocene rocks from Jinggu, western Yunnan, China: evidence for internal deformation of the Lanping–Simao

cr

Terrane

us

Liang Gao a, Zhenyu Yang a, b, *, Yabo Tong a, b, Heng Wang a, Chunzhi An a Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China

b

Key Laboratory of Paleomagnetism and Tectonic Reconstruction, the Ministry of Land and Resources, Beijing 100081, China

*Corresponding author. Tel.: +86-01088815152

Ac

ce

pt e

d

E-Mail address: [email protected] (Zhenyu Yang).

M

an

a

Page 1 of 48

ip t

cr

Abstract: Cretaceous, Paleogene, and Miocene sandstones were sampled in the Jinggu area to constrain the internal deformation of the Lanping–Simao Terrane of the Indochina Block. The tilt-corrected overall site-mean direction of the middle Cretaceous strata recorded in the Jinggu area is Ds/Is = 77.0°/43.0°, with α95 = 2.9° (N =

us

47), with a positive fold test indicating a primary remanence acquisition. The site-mean direction recorded for the high-temperature component of the Miocene strata is

an

Ds/Is = 13.7°/36.0°, with α95 = 3.3° (n = 38). The best-fit linear regressions between regional tectonic lines and rotation degree from each sampled area in the Lanping–Simao Terrane indicate a direct relationship between tectonic rotation and formation of the sinusoidal shape of the Lanping–Simao arcuate structural zone. The

M

large clockwise rotation in the Jinggu area can be subdivided into three periods. During the formation of the sinusoidal shape of the Lanping–Simao Arc, the Jinggu area and the Indochina Block experienced approximately 20° of clockwise rotation. An additional ~40° of clockwise rotation in the Jinggu area was caused by bending of the

d

Chongshan–Lancang–Chiang Mai belt between 27 and 20 Ma. After the early Miocene, a significant small-scale internal rotation (8.2±3.2°) adjustment occurred in the

pt e

Jinggu area. Quantitative comparison between the paleomagnetically-determined clockwise rotation and tectonic–metamorphic events suggests that the Lanping-Simao

ce

Arc was formed by the west-to-east compression and southeastward extrusion of the Shan–Thai Terrane since 36 Ma in southeast Tibet.

1. Introduction

Ac

Keywords Paleomagnetism, Lanping–Simao Terrane, Cretaceous, Miocene, Sanhaogou Formation, Tectonic deformation

The India–Asia collision induced about 2500 km of crustal shortening between the Indian and Eurasian plates and caused tectonic deformation within the Asian continent (Besse et al., 1984; Najman et al., 2010; Patriat et al., 1984; Yang et al., 1998), starting in the latest Cretaceous or early Paleocene (Ding et al., 2005; Yin and Harrison, 2000), or in the early Eocene (ca. 50 Ma) (Jaeger et al., 1989; Klootwijk et al., 1985; Liebke et al., 2010; Molnar and Tapponnier, 1975; Rowley, 1996). However, how this convergence (of more than 2000 km) was absorbed during the collision remains controversial, and several geo logical models have been proposed Page 2 of 48

(Avouac and Tapponnier, 1993; England and McKenzie, 1982; Houseman and England, 1986, 1993; Lacassin et al., 1997; Peltzer and Tapponnier, 1988; Royden et al.,

ip t

1997, 2008; Tapponnier et al., 1982; Vilotte et al., 1986).

cr

There are two end-member models which are commonly used to describe the mechanisms. The first is the 'tectonic escape' model (e.g. Molnar and Tapponnier, 1975; Replumaz and Tapponnier, 2003; Tapponnier et al., 1982); and the second is the 'crustal flow' model (e.g. Bird, 1991; Clark and Royden, 2000; Royden et al., 1997).

us

However, it is clear that there other possibilities which could explain the crustal deformation in Tibet (for summaries, see e.g., DeCelles et al., 2002; Dewey et al., 1988,

an

1989; England and Houseman, 1988, 1989; England and Molnar, 1990, 1997; Kapp et al., 2005; Van Hinsbergen et al., 2011). Southeastern Tibet consists of many mosaic blocks (e.g., the Shan–Thai Block, the Indochina Block, and the Chuandian Fragment; Fig. 1). The Shan–Thai Block

M

plays a key role in understanding intracontinental deformation processes after the India–Asia collision. Many paleomagnetic studies have been carried out on the Shan–Thai and Indochina blocks over the past two decades. The results indicate that these two blocks have undergone clockwise rotation and large-scale SE extrusion

d

since the Paleocene (Chen et al., 1995; Huang et al., 1993; Sato et al., 1999, 2001, 2007; Yang and Besse, 1993; Yang et al., 2001a, b; Zhang et al., 2012). The

pt e

Lanping–Simao Terrane occupies the northern part of the Shan–Thai Block and underwent significant tectonic deformation in the Cenozoic (Wang and Burchfiel, 2000; Zhang et al., 2004). Cretaceous to Eocene sedimentary strata were deposited in the Lanping–Simao Terrane, and these rocks have provided samples for the study of the

ce

complex internal differences in the rotational deformation and lateral movement of the mosaic blocks (Chen et al., 1995; Funahara et al., 1993; Huang et al., 1993; Kondo et al., 2012; Sato et al., 1999; Sato et al., 2007; Takemoto et al., 2009; Tanaka et al., 2008; Yang et al., 2001a, b).

Ac

Several deformation models have been proposed to explain the rotational deformation of the Lanping–Simao Terrane (Kondo et al., 2012; Tanaka et al., 2008; Tong et al., 2013). All of these models considered a close relationship between the sinusoidal shape of the Chongshan-Lanping-Chiang-Mai Belt (CLCMB) and differential rotation within the Lanping–Simao Terrane. However, controversy remains over when and how the sinusoidal shape of the CLCMB was finally formed. Tanaka et al. (2008) ascribed the interval of deformation to 32–27 Ma, and proposed that north–south compressive stress during this period played a key role in shaping the CLCMB structure. Conversely, Kondo et al. (2012) and Tong et al. (2013, 2014) proposed that the sinusoidal shape of the CLCMB formed after the Pliocene as a result of movement of CDF crustal material from northeast to southwest. After considering the main differences between these two models, we selected the Jinggu area, situated in the central Simao Terrane, for study in order to further constrain the deformation behavior of the Jinggu area and the Lanping–Simao Terrane. To avoid confusing local Page 3 of 48

rotation caused by small faults with the larger-scale rotation of the Jinggu area during deformational model building, we used samples obtained from both close to, and

ip t

distant from, the faults selected for our paleomagnetic study (Chen et al., 1995; Li et al., 2005; Piper et al., 1997). Miocene strata were also sampled to test the possibility

cr

of post-Pliocene differential rotation within the Simao Terrane. The purpose of the study is the precise delineation of the deformational patterns of the Jinggu area in the Lanping–Simao Terrane by combining the previous paleomagnetic results with our new data.

us

2. Geological setting and sampling

an

The Shan–Thai Block, which underwent strong deformation during the Cenozoic, is situated to the SE of the eastern Himalayan syntaxis (Wang and Burchfiel, 2000; Zhang et al., 2004) and includes the Baoshan Terrane and the Simao Terrane. As shown in Fig. 1, this block is separated from the CDF by the NW–SE trending JSRF to

M

the northeast. The Gaoligong shear zone (GLSZ) separates the Shan–Thai Block from the Tengchong Terrane to the west. To the SE, the Shan–Thai Block is separated from the Indochina Block by the Dien Bien Phu Fault (Fig. 1a). Previous studies have shown that the Dien Bien Phu Fault was a right-lateral strike-slip fault that has

d

become a left-lateral strike-slip fault during the last 5 Ma, and has a slip distance of about 12 km (Lai et al., 2012; Lepvrier et al., 1997; Tapponnier et al., 1982).

pt e

The Simao Terrane contains Proterozoic basement and Paleozoic marine sedimentary rocks and experienced intense tectonic deformation during the Cenozoic that resulted in the development of a fold system involving strata of Jurassic to Paleogene age in the Simao Terrane (BGMRY, 1990). Mesozoic to Paleogene continental

ce

sediments unconformably overlie pre-Mesozoic strata in the Simao fold belt, which were folded during the Eocene–Oligocene (BGMRY, 1990). Jinggu city is located about 100 km west of the Red River Fault, which is situated in the central part of the Simao Terrane (Fig. 1). Cretaceous, Paleogene, and

Ac

Miocene strata are widely exposed in the area. Approximate NW–SE-striking faults and folds, with axes trending NE–SW, are present in the Cretaceous and Paleogene strata in this region (BGMRY, 1990; Li, 1995). Three sampling sections were chosen in Cretaceous and Paleogene rocks in the western, central, and southern areas around Jinggu (Fig. 2).

We carried out two field sampling campaigns (July–August 2012 and May 2014) and four sections were sampled, with a total of 99 sampling sites. The Jinggu Cretaceous and Paleogene section is located in the western and southern part of Jinggu (Fig. 2). The Cretaceous sequence is mainly composed of two formations (Fig. 2) (BGMRY, 1990): the Jingxing and Mangang formations. The occurrence of the bivalves Koreanaia yunnanensis and Nippononaia (Eonipponaia) Diana, and the ostracods Cypridea (C.) angusticaudata, Darwinula postitruncate and Damonella depressa, indicates an Early Cretaceous age for the Jingxing Formation (BGMRY, Page 4 of 48

1990). The discovery of the bivalves Nakamuranaia chingshanensis and Nippononaia carinata, Trigonioides (T.) cf. kodairai and Peregrinoconcha aff. yunnanensis, and

ip t

the ostracods Monosulcocypris yunlongensis and Cypridea (C.) dayaoensis in the Mangang Formation, suggests an Early Cretaceous age for this formation (BGMRY,

cr

1990). The Paleogene sequence is mainly composed of the Paleocene Mengyejing Formation, the Eocene Denghei Formation, and the Eocene–Oligocene Mengla Group (BGMRY, 1990). The Mengyejing Formation contains the ostracods Sinocypris yunlongensis, S. cf. multipunctus, Quadracypris pulcher and Cypris yunnanensis,

us

indicating a Paleocene age (BGMRY, 1990). The Eocene Denghei Formation is a fine-grained sequence dominated by mudstone and siltstone. The age of this formation

an

has been estimated by stratigraphic correlation with fossiliferous beds in neighboring areas because no fossils have been found in the study area (BGMRY, 1990). The Eocene–Oligocene Mengla Group can be separated into three parts based on the lithology and sedimentary cycles (Liu et al., 1998). The lower part consists of

M

medium-coarse and fine-grained grayish-purple sandstone. The middle part contains fine-grained redbeds, and gray to purple conglomerate. The conglomerates are predominantly composed of granite particles that were derived from the CLCMB. The upper part of the group mainly consists of gray and purple medium-coarse and

d

fine-grained sandstone with yellow and purple conglomerate. The clastic sediments that form the conglomerate came from the CLCMB, the Mengyejing, and the Denghei 40

Ar–39Ar dating, demonstrates that the Mengla Group was deposited

pt e

Formations. Stratigraphic correlation based on the fossil content and lithology, together with between 38 and 29 Ma (Wang et al., 2001; Zhou et al., 2003).

ce

Our sampling sites were distributed across both limbs of a series of synclines. Three sampling sites were in the red mudstone and sandstone of the Mengla Group that conformably overlies the Denghei Formation. Seven sites were sampled in the Mengyejing Formation, which consists of red mudstone and siltstone. Sixty sites were

Ac

sampled in the Mangang Formation, which mainly consists of gray-purple and purple-red muddy siltstone. The Jingxing Formation mainly consists of purple-red siltstone and samples were obtained from two sites in this formation. The Sanhaogou Formation in the central Jinggu Basin mainly consists of gray and yellow sandstone. This formation unconformably overlies the Mengyejing Formation and the Mengla Group. The age of the Sanhaogou formation was determined from the presence of the well-known Jinggu flora, which has been dated to the Early Miocene (average age 20 Ma) (BGMRY, 1990). A total of 27 sites were sampled in the uniformly-dipping Sanhaogou Formation (JN section). Around 10 independent oriented cores were obtained from each site using a portable gasoline-powered drill. The cores were oriented using a magnetic compass. The location of each sampling site was determined using a portable GPS. The local geomagnetic declination value (D = −1.1) was calculated using the 11th Generation International Page 5 of 48

Geomagnetic Reference Field (Finlay et al., 2010).

ip t

3. Laboratory procedures

cr

In the laboratory, a specimen 25.4 mm in diameter and 23 mm in height was prepared from each sample. The natural remanent magnetization (NRM) of each specimen was measured using a 2G Enterprises cryogenic magnetometer (SQUID). All samples were measured in the paleomagnetism laboratory at the Institute of

us

Geomechanics, Beijing. All samples were progressively thermally demagnetized over 17 steps in an ASC TD-48 oven with an internal residual field lower than 10 nT.

an

The demagnetization temperature intervals were generally large (50–100C) in the lower part (below 500C), but small (30C) at higher temperatures (above 500C). The magnetic behavior of each specimen after complete demagnetization was plotted on a Zijderveld diagram (Zijderveld, 1967). Principal component analysis

M

(Kirschvink, 1980) was used to determine the directional behavior of different magnetization components. Site-mean directions were calculated using Fisherian statistics (Fisher, 1953). Paleomagnetism software (KIRSCH, PMCALC, PMSTAT, and SheepShave) developed by Enkin (1994) and Cogné (2003) was used to analyze the data.

d

4. Rock magnetism

pt e

Rock magnetic properties were investigated using representative specimens from the study sites. Based on the lithologic characteristics of the samples, 8 representative specimens were selected from the sampling sections, covering the Eocene-Oligocene Mengla Group (3 samples), Paleocene Mengyejing (1 sample) and

ce

Lower Cretaceous Mangang Formation (Jingxing Formation) (4 samples). Progressive acquisition of isothermal remanent magnetization (IRM) was performed up to a maximum field of 2.5 T (Tesla) using a 2G-pulse magnetizer. Thermal demagnetization of three-component IRMs (fields of 2.2, 0.4, and 0.12 T were applied along the z,

Ac

y, and x axes of each specimen, respectively) was conducted to isolate the unblocking temperature spectra (Lowrie, 1990). The IRM acquisition curves showed an initial rapid increase, with an upward convex profile, up to 100 mT, signifying the presence of magnetite. The saturation field was more than 2.5 T, revealing that hematite is the dominant magnetic carrier in the Cretaceous redbeds of the Jinggu area (Fig. 3). Thermal demagnetization of three-component IRMs suggests an unblocking temperature of around 680°C for all three components (Fig. 4). The decrease in intensity around 300-350C and 580C indicates the presence of pyrrhotite or titanomagnetite and magnetite. Thermal demagnetization of three-component IRMs from samples of the JN section showed that the medium and hard components unblock at 580°C (Fig. 5), indicating the presence of magnetite as the main magnetic carrier. IRM acquisition curves show a maximum coercivity of about 0.2–0.4 T, further confirming the presence of magnetite (Fig. 6). Page 6 of 48

These results indicate that both hematite and magnetite are carriers of HTC/ITC in the redbed samples of the JY (Section from Jinggu to Yizhi (village names)), JE

ip t

(Eocene Section in Jinggu), and JP (Section from Jinggu to Yongping (city name)). The results from the JN (Neogene Section in Jinggu) samples suggest that magnetite is

cr

the dominant magnetic carrier. 5. Anisotropy of magnetic susceptibility

us

We measured the anisotropy of magnetic susceptibility (AMS) for 235 Cretaceous samples and 148 Miocene samples from different sampling sites using a KLY-3

an

Kappabridge. The relationship between L (k1/k2) and F (k2/k3), and P and T determines the shape of the AMS ellipsoid (Jelinek, 1981). Most samples from both periods had values of F larger than those of L, and values of T greater than zero (Fig. 7a and d), indicating that the AMS ellipsoids for these samples are oblate in shape. The

M

shape of the AMS ellipsoids indicates that tectonic stress can be ignored, as it has little influence on the remanence direction. The direction of the maximum (k1), intermediate (k2), and minimum (k3) ellipsoid axes of the middle Cretaceous and Miocene samples are shown on Rose diagrams in Fig. 7b and e, respectively.

d

The direction of k1 can reflect extensional or compressional settings. When k1 develops in compressional settings, it is normally parallel to the fold axis, whereas it is

pt e

perpendicular to the strike of the bedding in extensional contexts (Mattei et al., 1997). In the Rose diagram, k1 is arranged parallel to the bedding strike and fold axis in the Cretaceous and Paleogene sampling areas (Fig. 7b), indicating that the magnetic fabric was formed during compressional tectonics (Mattei et al., 1997). Parallelism

ce

between k1 and the fold axis direction within the Lanping–Simao Basin was also recognized in the Simao area (Sato et al., 2007), which further confirms the tectonic origin of the observed magnetic lineation, implying that k1 is a passive marker that was rotated after formation as part of stratal shortening (Fig. 7c). AMS results indicate

Ac

that samples from sites in the JN section preserve an initial deformation magnetic fabric (Fig. 7d). The axial distribution of AMS of these samples after tilt correction shows that the k3 axes are generally vertical, although the k1 and k2 axes are separated in the horizontal plane (Fig. 7d and e). The magnetic lineation (k1) roughly trends NE–SW, almost perpendicular to the bedding strike, implying that k1 was developed in an extensional setting (Fig. 7e and f). Geological surveys have shown that the Miocene Jinggu basin is a strike-slip pull-apart basin bounded by two NE–SW strike slip faults that are aligned NW–SE (Fig. 7f) (BGMRY, 1990), which is consistent with our AMS results. 6. Paleomagnetic results 6.1. Cretaceous and Paleogene JY, JP, and JE sections Page 7 of 48

Samples from the Cretaceous Mangang Formation in this area revealed initial natural remanent magnetization (NRM) intensities between 2.4 and 9.2 mA/m. One

ip t

type of specimen generally showed two components of magnetization. After the removal of the low-temperature component (LTC) by 350°C, the high-temperature

cr

component (HTC) After removal of the low-temperature component (LTC) at 350°C, the high-temperature component (HTC) (unblocking temperature 690°C) decayed linearly towards the origin (Fig. 8e1, f1, g1, h1, j1 and d2,). The second type of specimen exhibited three components of magnetization (Fig. 8a1, b1, c1, d1, i1, a2, b2,

us

and c2). The LTC was isolated between 50°C and 300°C, and then an intermediate-temperature component (ITC) separated between 300°C and 580°C. The HTC was

an

isolated between 580°C and 690°C. However, there was no major change in the direction of the magnetic vector between these two components (ITC and HTC) after the Zijderveld plot analysis. The third type exhibited one stable HTC (Fig. 8e2, f2 and g2). The remaining samples (9 sampling sites, Table 1) exhibited unstable

M

demagnetization behavior at high heating temperatures (500–690°C, Fig. 8k1, l1, h2, and i2). The LTC was observed in 18 samples. The formation mean direction of this component is Dec./Inc. = 9.3°/31.4°, k = 15.0, α95 = 9.2° in geographic coordinates,

d

which is almost identical to the present-day geomagnetic field (D = −1.1°, I = 35.3°, Fig. 9a and b). This type of behavior indicates a viscous remanent magnetization

pt e

(VRM) origin for this component.

The ITC was observed in 80 samples. The site-mean direction is Dg = 71.1°, Ig = 39.4°, κ = 6.8, with α95 = 6.5° in in situ coordinates and Ds = 76.9°, Is = 44.0°, κ =

ce

28.5 with α95 = 3.0° after tilt correction, which passes the fold test at the 99% confidence level according to the McElhinny (1964) method (ks/kg = 4.17＞F(158, 158) = 1.46). However, it is inconclusive at the 95% confidence level according to the McFadden (1990) method (ζ1(in situ) = 53.52, ζ1(tilt corrected ) = 28.78, ζ95% = 10.40)

Ac

(Fig. 9c and d). The precision parameter (k) for the mean directions of the 80 samples increased from 6.8 to 28.5 (ks/kg = 4.2) after tilt correction; the difference in direction from the LTC suggests that the ITC was acquired before folding. The HTC was isolated from 47 sites (403 samples) of the Cretaceous Mangang Formation. Most samples showed normal polarity, indicating that the Mangang Formation was probably deposited during the Cretaceous Long Normal Superchron (CLNS) in the middle Cretaceous (Yang et al., 2001b). The overall site-mean direction is Dg = 73.4°, Ig = 42.8°, κ = 7.6, with α95 = 8.1° in in situ coordinates, and Ds = 77.0°, Is = 43.0°, κ = 54.0 with α95 = 2.9° after tilt correction. The results pass the fold test at the 99% confidence level according to the McElhinny (1964) method (ks/kg = 7.11＞F(92, 92) = 1.63), and the McFadden (1990) method (ζ1(in situ) = 30.18, ζ1(tilt corrected) = 6.85, ζc = 11.28 at the 99% confidence level (Fig. 9e and f). These positive fold tests support a pre-folding origin for the HTC. In order to Page 8 of 48

evaluate the influence of faults and possible local rotations, we divided the sampling area into five sub-areas that were separated by faults, and calculated the mean

ip t

direction of each (Figs. 2 and 10). All site-mean directions from the five sub-areas pass the fold test according to the McElhinny (1964) or McFadden (1990) methods

cr

(Fig. 10, Table 1). The different declinations among these five sub-areas are caused by the slight internal deformation within them (Figs. 2 and 10). The overall site-mean direction from five sub-areas (47 sites) gave a small α95 of 2.9°, and we suspected that the geomagnetic secular variation (GSV) may not have been averaged out. In this

us

case, we calculated the angular dispersion (SB) of VGPs based on the method proposed by Biggin et al. (2008). We used the variable parameters a = (11.3-7.8)，b =

an

(0.29-0.22) during the Cretaceous Normal Superchron (CNS, 84-125 Ma). The SB is 11.43, which falls in the range of SB = (13.43-9.54), suggesting that the data average out the GSV. We also note that the sampling section covers more than 1 km thickness, suggesting that the sediment deposition time was long enough to average out the

HTC for the subsequent discussion of deformation.

M

GSV. Considering the small number (80) of three-component magnetization samples, and the similarity in direction between ITC and HTC (Fig. 9d and f), we use the

d

The HTC from the Early Cretaceous Jingxing Formation (JP23 in Table 1) and the Paleocene Mengyejing Formation (JP01 in Table 1) show the same direction as

pt e

those of the middle Cretaceous Mangang Formation; thus, we use the overall mean direction of these three formations to calculate the degree of rotation of the Jinggu area since the middle Cretaceous.

ce

6.2. Miocene JN section

Orthogonal vector plots of thermal demagnetization of representative samples from the Sanhaogou Formation are shown in Fig. 11. The NRM intensities of the

Ac

samples fall within the range of 1.0-5.5 mA/m. The demagnetization characteristics can be divided into five categories. One type of sample (n = 17) showed two stable components of magnetization during progressive thermal demagnetization (Fig. 11b, c, d, f and g). The LTC was isolated around 200°C. After removal of the LTC, an HTC appeared above 300°C (about 300-580°C), which decays towards the origin. Directions below 200°C represent a viscous magnetization acquired in the direction of the present-day geomagnetic field. The second type of sample (n = 3) showed three stable components of magnetization during progressive thermal demagnetization. After removal of the LTC around 200°C, an ITC appeared between 200°C and 400°C. The HTC with unblocking temperatures just above 500°C was obtained (Fig. 11a). The third type (n = 16) shows one stable HTC of magnetization (Fig. 11e). In the fourth type (n = 29), the LTC was isolated at around 200°C, and ITC at around 200-400°C; however, the HTC (above 500°C) could not be isolated (Fig. 11h). In the fifth type (n = 24), the LTC could be isolated but the directions became erratic Page 9 of 48

above 300°C (Fig. 11l). The low-temperature magnetic components were isolated between 20°C and 200°C from 73 samples, which gave a mean direction with Dg =

ip t

354.5°, Ig = 36.2°, k = 14.0, α95 = 4.6° before tilt correction, and Ds = 337.1°, Is = 25.0°, k = 11.3, α95 = 5.2° after tilt correction (Fig. 12a and b). The LTC represents a

cr

viscous magnetization acquired in the present-day geomagnetic field. The number of samples containing ITC was too small to perform a meaningful statistical calculation.

us

The mean HTC direction (n = 38) of all samples is Dg = 32.3°, Ig = 26.9°, κ = 59.9, with α95 = 3.0° in in situ coordinates, and Ds = 13.7°, Is = 36.0°, κ = 49.8 with

an

α95 = 3.3° after tilt correction (Table 2, Fig. 12c and d). Because of the monoclinal nature of the sampling section, the fold test is inconclusive at the 95% confidence level according to the McElhinny (1964) method (ks/kg = 1.20＜F(74, 74) = 1.46), and inconclusive at the 99% confidence level according to the McFadden (1990)

M

method (ζ1(in situ) = 4.48, ζ1(tilt corrected) = 7.88, ζc = 10.14). However, there are two reversed polarity samples (JN 22-5 and 21-9), as well as 15 samples (JN1-1, 1-4, 1-5, 1-6, 1-8, 1-10, 2-6, 3-3, 4-2, 4-9, 13-10, 16-3, 21-8, 22-3 and 22-4) which exhibit a reversing tendency along the great circles (Fig. 11d, f , i, j, m, n, o and p). We

d

note that the mean HTC direction before tilt correction is significantly different to the present dipole field, and this evidence suggests that the HTC directions are

pt e

probably of primary origin. Because the ChRM was separated in only 38 samples, the calculation of a site-mean direction is tentative (Table 2). If we take the sites with samples more than and equal to 2, the site-mean direction is almost the same as that of the sample-level mean direction. Considering the limited number of samples from

ce

each site, we prefer to use the sample-level mean ChRM direction for further discussion. The remaining samples (n = 243) exhibited unstable behavior during thermal demagnetization (Fig. 11k) and were rejected from further analysis.

Ac

7. Discussion

Characteristic magnetic components were isolated in the samples from our study sections. Combining our results with previously paleomagnetic data (Table 3) enables us to estimate the tectonic rotation pattern of the Lanping–Simao Terrane with respect to Eurasia. The high quality of the paleomagnetic data, after careful evaluation using reliability criteria (Q ≥ 4) (Van der Voo, 1990), demonstrates that they can be used to shed further light on the deformation (Table 3). Our results are almost entirely consistent with those of previous studies in the Jinggu area (Chen et al., 1995; Huang and Opdyke, 1993; Yang et al., 2001a) (Table 3, Fig. 13a). The same degree of rotation between Cretaceous and 38–29 Ma (Mengla Group) rocks indicates that large clockwise rotation (ca. 70°) occurred after 38 Ma (Fig. 13a). The clockwise rotation calculated from the results for the Sanhaogou Formation and the Eurasian reference pole (20Ma) is 8.2±3.2°, which is barely consistent Page 10 of 48

with Chen et al. (1995) (15.7±5.6°) at the 95% confidence level (Table 3, Fig. 13a).The difference in rotation between the Eocene–Oligocene (38–29 Ma) and the early

ip t

Miocene (20Ma) indicates that about 60° of clockwise rotation occurred between the late Eocene (38 Ma) and the early Miocene (20Ma). After the early Miocene, the

cr

Jinggu area experienced small-scale clockwise rotation (8.2±3.2°). 7.1. Oroclinal bending of the Lanping–Simao arcuate structural zone

us

Previous summaries of paleomagnetic data from the Lanping–Simao Terrane demonstrated the close relationship between the Lanping–Simao arcuate structural zone

an

and differential tectonic rotation (Kondo et al., 2012; Tanaka et al., 2008; Tong et al., 2013). Following the method of Schwartz and Van der Voo (1983), we used the linear regression technique to reveal the relationship between the arcuate structural zone in the Lanping–Simao Terrane and the internal rotational deformation. Selection

M

of S (average strike) and S0 (reference strike) was performed with reference to the studies of Kondo et al. (2012) and Tong et al. (2013, 2014). The degree of rotation and S0-S of each sampled area were plotted on an orthogonal coordinate system (Fig. 13c). The best-fit linear regression yields a correlation coefficient of R = 0.96, indicating

d

an excellent correlation between the tectonic rotation and the related tectonic line of the Lanping–Simao arcuate structural zone. A value of 20° is estimated for the total

pt e

amount of tectonic rotation of the Lanping–Simao Terrane (Fig. 13c), which is consistent with rotational results from the Indochina Block (Table 3) (Charusiri et al., 2006; Yang et al., 1993), indicating that the Lanping–Simao Terrane and the Indochina Block once rotated as a whole and experienced about 20° clockwise rotation (Fig. 13c). Ar–39Ar dating of micas from the Bu Khang extensional gneiss dome in Vietnam gave ages of 36 to 21 Ma, which was inferred to have resulted from the clockwise

ce

40

rotation of the Indochina Block and the opening of the South China Sea (Jolivet et al., 1999). Thus, the 20° clockwise rotation of the Lanping–Simao Basin and the

Ac

Indochina Block may have occurred during the 36–21 Ma interval. Large-scale clockwise rotation of about 60° occurred in the Jinggu area between the Eocene–Oligocene (38–29 Ma) and the early Miocene (20Ma). Thus, being one of the most important places for the best-fit linear regression calculation, paleomagnetic data from the Jinggu area prove that the sinusoidal shape of the Lanping–Simao arcuate structural zone should have been formed between the late Eocene (38 Ma) and the early Miocene (20Ma). Most of the paleomagnetic research areas in the Shan–Thai Block are distributed in the Lanping–Simao arcuate structural zone along the CLCMB (Fig. 1b). The sinusoidal-shaped trends of folds and faults in the Simao arcuate structural zone are parallel to the curvature of the CLCMB, implying that the sinusoidal shape of the Lanping–Simao arcuate structural zone formed through bending of the CLCMB (Kondo et al., 2012; Tanaka et al., 2008; Tong et al., 2013, 2014). With the formation of Page 11 of 48

the sinusoidal-shaped trend of the CLCMB, a series of almost north–south striking thrust faults were formed within the belt (Fig. 14b) (Yang, 1996). This thrust fault

ip t

directionality within the CLCMB (Fig. 14b) allows us to propose that thrusting within the CLCMB occurred from west to east. Geological surveys have shown that the

cr

thrusting distance of the thrust faults within the CLCMB is about 60–120 km (Fig. 15g) (Yang, 1996). K–Ar dating of synkinematic minerals (potash feldspar and muscovite) revealed that two periods of thrust faulting took place within the CLCMB, at 25.6 and 15.4 Ma (Fig. 14b) (Yang, 1996). Fission-track studies showed that the

us

two periods of thrusting-related rapid uplift within the CLCMB started at 36 Ma in the southern granite belt and at 26.5–21 Ma in the central and northern granite belt

an

(Fig. 14b) (Shi et al., 2006). These times of deformation coincide with those estimated from the paleomagnetic data from the Jinggu area, which further confirms our conclusion that bending of the Simao arcuate structural zone began at 38 Ma and continued until about 20 Ma. Because the Jinggu area is located near the central granite

M

belt, the extra 40° (approximately) of clockwise rotation that occurred as regional rotation within the Jinggu area may have taken place during the period 27–20 Ma. 7.2. Block rotation and tectonic deformation associated with the faulting process in SE Tibet

d

Tectonic deformations related to fault and fold formations in SE Tibet provide hints on the timing of tectonic rotation. As mentioned above, a model to explain the

pt e

diachronism of thrusting within the CLCMB is proposed. First, with the indention of the Namche–Barwa Syntaxis (NBS), a strong compression zone formed between the NBS and JSRF (Fig. 15c). Since 40 Ma, rapid northward movement of the eastern corner of the Indian plate with respect to the Indochina Block occurred, resulting in

ce

high-grade granulite facies metamorphism within the NBS at 40 Ma (Ding et al., 2001) or 37–32 Ma (Zhang et al., 2010b), as well as emplacement of syntectonic hornblende syenites and leucogranites between 35 and 23 Ma in the Mogok metamorphic belt, Myanmar, near the Sagaing fault (Barley et al., 2003). In addition,

Ac

SHRIMP (Sensitive High Resolution Ion Microprobe) and LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) U–Pb ages of 31.3–25.5 Ma date the tectonic–metamorphic event after initial oblique collision in the NBS (Xu et al., 2012) (Fig. 1a). Anatectic zircons from granitic leucosomes in weakly-deformed migmatites of the JSRF record two metamorphic events, at 33.7±0.3 to 30.9±0.3 Ma and 27.8±0.2 to 26.3±0.3 Ma (U–Pb age) (Liu et al., 2014). A detailed analysis of the geochronological database for the JSRF shows that sinistral motion was probably active prior to 36 Ma, certainly at 32 Ma, and lasted until shortly after 17 Ma, while the induced cooling diachronism observed at Ailaoshan suggests left-lateral movement rates of 4 to 5 cm/yr from 27 Ma until about 17 Ma (Cao et al., 2011; Gilley et al., 2003; Leloup et al., 2001; Lu et al., 2012). To the west, the Gaoligong shear zone was active between ~20-11 Ma (e.g., Eroglu et al., 2013; Wang et al., 2008; Zhang et al., 2012) and anatectic zircons from granitic leucosomes in weakly deformed migmatites within the GLSZ also yield consistent mean U–Pb ages of 40.6±0.3 to 38.4±0.2 Ma Page 12 of 48

and 27.8±0.2 to 26.3±0.3 Ma (Liu et al., 2014), implying that the GLSZ experienced multiple metamorphic events. The Chongshan (Lancangjiang) Shear Zone (CSSZ) is

ip t

the boundary between the Baoshan and Simao terranes (Wang and Burchfiel, 2000), and can be divided into northern (CN), middle (CM), and southern (CS) segments

cr

(Fig. 1b) (Zhong et al., 2004). It is situated between the NBS and the JSRF and experienced two periods of thrusting-related rapid uplift during 36–20 Ma in the southern, and 27–15 Ma in the central and north, granite belt (Shi et al., 2006) (Fig. 1a). The early period of thrusting in the southern granite belt (36–20 Ma) provided the clastic

us

sedimentary material for the middle and upper parts of the Mengla Group (38–29 Ma) (Fig. 15b) (Liu et al., 1998). Following metamorphism at 36 Ma (Zhang et al.,

an

2010a), the CSSZ experienced sinistral strike-slip motion beginning at 32 Ma (Wang et al., 2006) or 34 Ma (Akciz et al., 2008) in the middle and southern segments, which continued until at least 22 Ma (Tang et al., 2013; Zhang et al., 2010a), 29–27 Ma (Wang et al., 2006), or 24 Ma (Akciz et al., 2008). The

40

Ar/39Ar ages of

M

synkinematic micas ranged from 19–14 Ma represent the time of right strike-slip shearing with coeval transpressional exhumation and uplift of the metamorphic rocks (Fig. 15f) (Zhang et al., 2010a; Zhong et al., 2004), which was contemporaneous with uplift of metamorphic rocks in the GLSZ (Lin et al., 2009) and corresponded to

d

thrusting-related uplift within the north CLCMB (26.5–15 Ma). Secondly, with the left-lateral strike-slip movement of the CSSZ, and about 700±200 km of left-lateral

pt e

strike-slip movement along the JSRF (Fig. 15g) (Cao et al., 2011; Gilley et al., 2003; Leloup et al., 1995; Leloup et al., 2001; Lu et al., 2012; Yang et al., 1995), the CLCMB moved from NW to SE (Kornfeld et al., 2014a) across the strong compression zone, and thrusting occurred from west to east in the northern and central part of

ce

CLCMB during 27–15 Ma, forming the Simao Arc (Fig. 15d and f).

However, due to the lack of more accurate age-constrained paleomagnetic data for the 36–29 Ma time interval, the degree of clockwise rotation that occurred during

Ac

this period was unclear. Considering the parallel relationship between the strike direction of the southern granite belt and the JSRF (ca. 145°) at present (Fig. 15g), we suggest that local rotation during this period can be ignored. The consistent clockwise rotation calculated from the Baoshan (35.5±7.5°) and the Tengchong Terranes (34.4±6.9°) indicate that both may have experienced a uniform rotation pattern since 30 Ma (Kornfeld et al., 2014a and b) (Fig. 13b). The slight differences in rotation between the Tengchong, Baoshan, Yongping, Zhenyuan, Zhengwan and Puer areas suggests that rotation within the Lanping–Simao Terrane occurred after 30 Ma (Table 3, Fig. 13b), which is consistent with the timing of large-scale left-lateral movement of the JSRF (27–15 Ma) and thrusting in the central and northern parts of the CLCMB between 26 and 15 Ma (Yang, 1996). Our model supports the hypothesis of Otofuji et al. (2010) who proposed that when the proto-eastern Himalayan syntaxis shifted to the NNE, significant clockwise Page 13 of 48

rotation occurred in a swath between 84°E and 98°E. In their model, the zone of significant clockwise rotation within Eurasia was constrained to a limited strip between

ip t

those longitudes (Fig. 15e). Thus, this study is a further step towards correlating the block rotation with the limited compression stress zone by clarifying the formation

cr

process of the Simao Arc since 36 Ma.

The Three Pagodas Shear Zone (TPSZ) and the Wang Chao Shear Zone (WCSZ) are located in the western part of the Indochina Block. These shear zones started

us

slipping at 36 and 33 Ma, respectively, possibly terminating around 33 and 30 Ma, respectively (Lacassin et al., 1997). Geochronological studies carried out in Southeast

an

Asia indicate that these shear zones (e.g., the JSRF, GLSZ, CSSZ, TPSZ, and WCSZ) have different onset and end times (Fig. 15) (Wang et al., 2006), which further confirms the conclusion of diachronous extrusion and deformation within the Indochina Block (Lacassin et al., 1997). The approximate 46° of clockwise rotation in the

M

Tengchong Terrane between 40 and 30 Ma represents an early period of localized internal deformation that occurred earlier than the internal rotation within the Simao Terrane of the Jinggu area (27–20 Ma) (Kornfeld et al., 2014b). The different initial timings of large-scale regional rotation between the Tengchong Terrane and the

d

Jinggu area provide quantitative support for diachronous block rotation. The Tengchong Terrane has probably remained in the compression zone since about 40 Ma, and,

pt e

because of the penetration of India into Asia, has experienced at least two intervals of strong localized rotation since about 36 Ma (Fig. 15c and d). 8. Conclusions

ce

(1) High-temperature magnetic components were isolated from the middle Cretaceous rocks in the Jinggu area. The tilt-corrected site-mean direction is Ds = 77.0°, Is = 43.0°, κ = 54.0 with α95 = 2.9°. Positive fold tests show that the high-temperature magnetic components represent the primary magnetization. For the Miocene strata,

Ac

the tilt-corrected site-mean direction for the HTC is Ds = 13.7°, Is = 36.0°, κ = 49.8 with α95 = 3.3°. (2) The best-fit linear regression between the rotation degree and regional tectonic lines indicates a direct relationship between tectonic rotation and formation of the CLCMB. Paleomagnetic data confirm that about 70° of clockwise rotation has occurred in the Jinggu area since the late Eocene. The overall amount of rotation can be separated into three different intervals. First, the Jinggu area experienced about 20° of clockwise rotation together with Indochina from 36–21 Ma. Subsequently, the Jinggu area experienced a further 40° (approximately) of clockwise rotation as part of the thrusting process from west–east thrust faults within the CLCMB between 27 and 20 Ma. The sinusoidal shape of the Lanping–Simao Arc also formed during the thrusting process. Lastly, after the early Miocene, the Jinggu area experienced a small-scale internal rotation adjustment (8.2±3.2°). Page 14 of 48

(3) Based on a comparison between the tectonic–metamorphic events and paleomagnetically-determined rotation, we propose that there was a significant compression

ip t

zone between the NBS and JSRF from about 40 Ma. The Lanping–Simao Arc was formed by the west to east compressional stress together with the southeastward

cr

extrusion of the Baoshan Terrane and the Shan–Thai Block along the GLSZ, CSSZ, and JSRF since 36 Ma in SE Tibet.

us

Acknowledgments

The data for this paper is available by contacting the author (Zhenyu Yang) via email at ([email protected]).

an

This work has been supported by the “National Natural Science Foundation of China (grant 41202162)”, “SinoProbe 08-01-01”, “China Geological Survey (grant

M

1212011120164)” and “Institute of Geomechanics of the Chinese Academy of Geological Sciences (grant DZLXJK201207)”. We are very grateful to two anonymous

Ac

ce

pt e

d

reviewers and Editor-in-Chief Wouter Pieter Schellart for their insightful and careful comments and suggestions which greatly improved our manuscript.

Page 15 of 48

ip t

References

Ac

ce

pt e

d

M

an

us

cr

Akciz, S.O., 2008. Geometry, kinematics and regional significance of the Chong Shan shear zone, Eastern Himalayan syntaxis, Yunnan, China. Geosphere 4 (1), 292-314, doi: 10.1130/GES00111.1. Avouac, J.P., Tapponnier, P., Bai, M., You, H., Wang, G., 1993. Active thrusting and folding along the northern Tien Shan and late Cenozoic rotation relative to Dzungaria and Kazakhstan. Journal of Geophysical Research 98, 6, 755-6, 804, doi: 10.1029/92JB01963. Barley, M.E., Pickard, A.L., Zaw, Khin., Rak, P., Doyle M.G., 2003. Jurassic to Miocene magmatism and metamorphism in the Mogok metamorphic belt and the India-Eurasia collision in Myanmar. Journal of Geophysical Research 22, 3, 1019, doi: 10.1029/2002TC001398. Besse, J., Courtillot, V., Pozzi, J.P., Westphal, M., Zhou, Y.X., 1984. Paleomagneitc estimates of crustal shortening in the Himalayan thrusts and Zangbo suture. Nature 311, 621-626, doi: 10.1038/311621a0. BGMRY, Bureau of Geology and Mineral Resources of Yunnan Province, Mineral Resources of Yunnan Province., 1990. Regional Geology of Yunnan Province, Geological Memories Series 1, 21, Geological Publishing House, Beijing (in Chinese with English abstract). Biggin, A.J., Van Hinsbergen, D.J., Langereis, C.G., Straathof, G.B., Deenen, M.H., 2008. Geomagnetic secular variation in the Cretaceous Normal Superchron and in the Jurassic. Physics of the Earth and Planetary interiors 169 (1), 3–19. Bird, P., 1991. Lateral extrusion of lower crust from under high topography, in the isostatic limit. Journal of Geophysical Research 96/B6, 10275-10286. Cao, S., Liu, J., Leiss, B., Neubauer, F., Genser, J., Zhao, C., 2011. Oligo-Miocene shearing along the Ailao Shan-Red River shear zone: Constraints from structural analysis and zircon U/Pb geochronology of magmatic rocks in the Diancang Shan massif, SE Tibet, China. Gondwana Research 19, 975-993. Charusiri, P., Imsamut, S., Zhuang, Z., Ampaiwan, T., Xu, X., 2006. Paleomagnetism of the earliest Cretaceous to early late Cretaceous sandstones, Khorat Group, Northeast Thailand: implications for tectonic plate movement of the Indochina block. Gondwana Research 9, 310-325, doi: 10.1016/j.gr.2005.11.006. Chen, H.H., Dobson, J., Heller, F., Jie, H., 1995. Paleomagnetic evidence for clockwise rotateon of the Simao region since the Cretaceous: a consequence of India-Asia Collision. Earth and Planetary Science Letters 134, 203-217, doi: 10.1016/0012-821X(95)00118-V. Clark, M., Royden, L., 2000. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow. Geology 28, 703-706. Cogné, J.P., 2003. PaleoMac: a MacintoshTM application for treating paleomagnetic data and making plate reconstructions. Geochemistry, Geophysics, Geosystems 4(1), 1007, doi:10.1029/2001GC000227. DeCelles, P.G., Robinson, D.M., Zandt, G., 2002. Implications of shortening in the Himalayan fold thrust belt for uplift of the Tibetan Plateau. Tectonics 21 (6), 1062, doi:10.1029/2001TC001322, 2002. Dewey, J.F., Shackleton, R.M., Chang, C.F., Sun, Y.Y., 1988. The tectonic evolution of the Tibetan Plateau. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 327, 379-413. Dewey, J.F., Helman, M.L., Knott, S.D., Turco, E., Hutton, D.H.W., 1989. Kinematics of the western Mediterranean. Geological Society, London, Special Publications 45(1), 265-283. Ding, L., Zhong, D., Yin, A., Kapp, P., Harrison, T.M., 2001. Cenozoic structural and metamorphic evolution of the eastern Himalayan syntaxis (Namche Barwa). Earth and Planetary Science Letters 192, 423-438, doi: 10.1016/S0012-821X (01)00463-0. Ding, L., Kapp, P., Wan, X., 2005. Paleocene-Eocene record of ophiolite obduction and initial India-Asia collision, south central Tibet. Tectonics 24 (3), doi: 10.1029/2004TC001729. England, P., McKenzie, D.P., 1982. A thin viscous sheet model for continental deformation. Geophysical Journal International 70 (2), 295-321, doi: 10.1111/ Page 16 of 48 j.1365-246X.1982.tb04969.x. England, P.C., Houseman, G.A., Osmaston, M.F., Ghosh, S., 1988. The mechanics of the Tibetan Plateau [and discussion]. Philosophical Transactions of the Royal

Ac

ce

pt e

d

M

an

us

cr

ip t

Society of London A: Mathematical, Physical and Engineering Sciences 326 (1589), 301-320. England, P.C., Houseman, G.A., 1989. Extension during continental convergence, with application to the Tibetan Plateau. Journal of Geophysical Research 94B, 17561–17579. England, P.C., Molnar, P., 1990. Right lateral shear and rotation as the explanation for strike-slip faulting in eastern Tibet. Nature 344, 140–142. England, P., Molnar, P., 1997. The field of crustal velocity in Asia calculated from Quaternary rates of slip on faults. Geophysical Journal International 130 (3), 551-582. Enkin, R.J., 1994. A computer program package for analysis and presentation of paleomagnetism data, Pacific Geoscience Centre. Geological Survey of Canada 16. Eroglu, S., Siebel, W., Danišík, M., Pfänder, J.A., Chen, F., 2013. Multi-system geochronological and isotopic constraints on age and evolution of the Gaoligongshan metamorphic belt and shear zone system in western Yunnan, China. Journal of Asian Earth Sciences 73, 218-239. Finlay, C.C., Maus, S., Beggan, C.D., Bondar, T.N., Chambodut, A., Chernova, T.A., Chulliat, A., Golovkov, V.P., Hamilton, B., Hamoudi, M., Holme, R., Hulot, G., Kuang, W., Langlais, B., Lesur, V., Lowes, F.J., Lühr, H., Macmillan, S., Mandea, M., McLean, S., Manoj, C., Menvielle, M., Michaelis, I., Olsen, N., Rauberg, J., Rother, M., Sabaka, T.J., Tangborn, A., Tøffner-Clausen, L., Thébault, E., Thomson, A. W.P., Wardinski, I., Wei, Z., T. Zvereva, I., 2010. International Geomagnetic Reference Field: the eleventh generation. Geophysical Journal International 183, 1216-1230. doi: 10.1111/ j.1365-246X.2010.04804.x. Fisher, R.A., 1953. Dispersion on a sphere. Proc R Soc A-Math Phys Eng Sci. 217, 295-305, doi: 10.1098/rspa.1953.0064. Funahara, S., Nishiwaki, N., Murata, F., Otofuji, Y., Wang Y.Z., 1993. Clockwise rotation of the Red River fault inferred from paleomagnetic study of Cretaceous rocks in the Shan-Thai-Malay Block of western Yunnan, China. Earth and Planetary Science Letters 117, 29-42, doi: 10.1016/0012-821X(93)90115-P. Gilley, L.D., Harrison, T.M., Leloup, P.H., Ryerson, F.J., Lovera, O.M., Wang, J.H., 2003. Direct dating of left-lateral deformation along the Red River shear zone, China and Vietnam. Journal of Geophysical Research 108, 2127, doi: 10.1029/2001JB001726, B2. Houseman, G., England, P., 1986. Finite strain calculations of continental deformation 1. Method and general results for convergent ones. Journal of Geophysical Research 91, 3651-3663, doi: 10.1029/JB091iB03p03651. Huang, K.N., Opdyke, N.D., 1993. Paleomagnetic results from Cretaceous and Jurassic rocks of South and Southwest Yunnan: evidence for large clockwise rotations in the Indochina and Shan-Thai-Malay Terranes. Earth and Planetary Science Letters 117, 507-524, doi: 10.1016/0012-821X(93)90100-N. Jaeger, J.J., Courtillot, V., Tapponnier, P., 1989. Paleontological view of the ages of the Deccan traps, the Cretaceous/Tertiary boundary, and the India-Asia collision. Geology 17, 316-319. Jelinek, V., 1981. Characterization of the magnetic fabric of rocks. Tectonophysics 79 (3), T63-T67, doi: 10.1016/0040-1951(81)90110-4. Jolivet, L., Maluski, H., Beyssac, O., Goffé, B., Lepvrier1, C., Thi, P.T., Vuong, N.V., 1999. Oligocene-Miocene Bu Khang extensional gneiss dome in Vietnam: geodynamic implications. Geology 27 (1), 67-70, doi: 10.1130/0091-7613(1999)027<0067:OMBKEG>2.3.CO;2. Kapp, P., Yin, A., Harrison, T.M., Ding, L., 2005. Cretaceous-Tertiary shortening, basin development, and volcanism in central Tibet. Geological Society of America Bulletin 117 (7-8), 865-878. Kirschvink, J.L., 1980. The least-squares line and plane and the analysis of paleomagnetic date. Geophysical Journal of the Royal Astronomical Society 62, 699-718, doi: 10.1111/j.1365-246X.1980.tb02601.x. Klootwijk, C.T., Conaghan, P.J., Powell, C.M., 1985. The Himalayan Arc: large-scale continental subduction, oroclinal bending and back-arc spreading. Earth and Planetary Science Letters 75, 167-183, doi: 10.1016/0012-821X (85)90099-8. Kondo, K., Mu, C., Yamamoto, T., Zaman, H., Miura, D., Yokoyama, M., Ahn, H.S., Otofuji, Y., 2012. Oroclinal origin of the Simao Arc in the Shan-Thai Block inferred from the Cretaceous palaeomagnetic data. Geophysical Journal International 190 (1), 201–216, doi: 10.1111/j.1365-246X.2012.05467.x. Page 17 of 48 Kornfeld, D., Eckert, S., Appel, E., Ratschbacher, L., Pfänder, A., Liu, D., Ding, L., 2014a. Clockwise rotation of the Baoshan block due to southeastward tectonic

Ac

ce

pt e

d

M

an

us

cr

ip t

escape of Tibetan crust since the Oligocene. Geophysical Journal International ggu009. Kornfeld, D., Eckert, S., Appel, E., Ratschbacher, L., Sonntag, B.L., Pfänder, A., Ding, L., Liu, D., 2014b. Cenozoic clockwise rotation of the Tengchong block, southeastern Tibetan Plateau: a paleomagnetic and geochronologic study. Tectonophysics 628 (30), 105-122, doi: 10.1016/j.tecto.2014.04.032. Lacassin, R., Maluski, H., Leloup, P.H., Tapponnier, P., Hinthong, C., Siribhakdi, K., Chuaviroj, S., Charoenravat, A., 1997. Tertiary diachronic extrusion and deformation of western Indochina: structural and 40Ar/39Ar evidence from NW Thailand. Journal of Geophysical Research 102, 10, 013-10, 037, doi: 10.1029/96JB03831. Lai, K.Y., Chen, Y.G., Lâm, D.Đ., 2012. Pliocene-to-present morphotectonics of the Dien Bien Phu fault in northwest Vietnam. Geomorphology 173-174, 52-68, doi: 10.1016/j.geomorph.2012.05.026. Leloup, P.H., Lacassin, R., Tapponnier, P., Zhong, D., Lui, X., Zhang, L., Ji, S., 1995. The Ailao Shan-Red River shear zone (Yunnan, China), Tertiary transform boundary of Indochina. Tectonophysics 251, 3-84, ssdoi: 0040-1951(95)00070-4. Leloup, P.H., Amaud, N., Lacassin, R., Kienast, J.R., Harrison, T.M., Phan Trong, T.T., Replumaz, A., Tapponnier, P., 2001. New constraints on the structure, thermochronology, and timing of the Ailao Shan-Red River shear zone, SE Asia. Journal of Geophysical Research 106, 6683-6732, doi: 10.1029/2000JB900322. Lepvrier, C., Maluski, H., Vuong, N.V., Roques, D., Axente, V., Rangin, C., 1997. Indosinian NW-trending shear zones within the Truong Son belt (Vietnam): 40Ar/39Ar Triassic ages and Cretaceous to Cenozoic overprints. Tectonophysics 283, 105-127, doi: 10.1016/S0040-1951(97)00151-0. Liebke, U., Appel, E., Ding, L., Neumann, U., Antolin, B., Xu, Q., 2010. Position of the Lhasa terrane prior to India-Asia collision derived from paleomagnetic inclinations of 53 Ma old dykes of the Linzhou Basin: constraints on the age of collision and post-collisional shortening within the Tibetan Plateau. Geophysical Journal International 182, 1199-1215. Lin, T.H., Lo, C.H., Chung, S.L., Hsu, F.J., Yeh, M.W., Lee, T.Y., Ji, J.Q., Wang, Y.Z., Liu, D., 2009. 40Ar/39Ar dating of the Jiali and Gaoligong shear zones: Implications for crustal deformation around the Eastern Himalayan Syntaxis. Journal of Asian Earth Sciences 34, 674-685, doi: 10.1016/j.jseaes.2008.10.009. Li, S.Q., 1995. Structural features of the Lanping-Simao, Yunnan Himalayan Fold Belt, mechanism of its formation and the tectonic significance (in Chinese with English abstract). Bulletin of the Institute of Aeromechanics CAGS 16, 1-10. Liu, F., Wang, F., Liu, P.H., Yang, H., Meng, E., 2014. Multiple partial melting events in the Ailao Shan-Red River and Gaoligong Shan complex belts, SE Tibetan Plateau: Zircon U-Pb dating of granitic leucosomes within migmatites. Journal of Asian Earth Sciences http://dx.doi.org/10.1016/ j.jseaes.2014.06.025. Liu S.Y., Zhong, D.L., Wu, G.Y., 1998. Jinggu-Zhenyuan transpressional basin during continent-continent collision of early Tertiary in southwest Yunnan, China (in Chinese with English abstract). Scientia Geologica Sinica 33 (1), 1-8. Li, Y.X., Ali, J.R., Chan, L.S., Lee, C.M., 2005. New and revised set of Cretaceous paleomagnetic poles from Hong Kong: implications for the Cretaceous- Cenozoic development of southeast China. Journal of Asian Earth Sciences 24, 481-493, doi: 10.1016/j.jsease.2004.01.004. Lowrie, W., 1990. Identification of ferromagnetic minerals in a rock coercivity and unblocking temperature properties. Geophysical Journal International 17, 159-162, doi: 10.1029/GL017i002p00159. Lu, Y., Kerrich, R., Cawood, P., McCuaig, T., Hart, C., Li, Z., Hou, Z., Bagas, L., 2012. Zircon SHRIMP U-Pb geochronology of potassic felsic intrusions in western Yunnan, SW China: Constraints on the relationship of magmatism to the Jinsha suture. Gondwana Research 22/2, 737-747. Mattei, M., Sagnotti, L., Faccena, C., Funiciello, R., 1997. Magnetic fabric of weakly deformed clay-rich sediments in the Italian peninsula: relationship with compressional and extensional tectonics. Tectonophysics 271, 107-122, doi: 10.1016/S0040-1951(96)00244-2. McElhinny, M.W., 1964. Statistical Significance of the fold test in paleomagnetism. Geophysical Journal Royal Astronomical Society 8, 338-340, doi: 10.1111/j.1365-246X.1964.tb06300.x. Page 18 of 48 McFadden, P.L., 1990. A new fold test for paleomagnetic studies. Geophysical Journal International 103, 163-169, doi: 10.1111/j.1365-246X.1990.tb01761.x.

Ac

ce

pt e

d

M

an

us

cr

ip t

Molnar, P., Tapponnier, P., 1975. Cenozoic tectonics of Asia: effects of a continental collision. Science 189, 419-426, doi: 10.1126/science. 189. 4201. 419. Najman, Y., Appel, E., Boudagher-Fadel, M., Brown, P., Carter, A., Garzanti, E., Godin, L., Han, J., Liebke, U., Oliver, G., Parrish, R., Vezzoli, G., 2010. Timing of India-Asia collision: Geological, biostratigraphic, and paleomagnetic constraints. Journal of Geophysical Research: Solid Earth 115/B12, DOI: 10.1029/2010JB007673. Otofuji, Y., Yokoyama, M., Kitada, K., Zaman, H., 2010. Paleomagnetic versus GPS determined tectonic rotation around eastern Himalayan syntaxis in East Asia. Journal of Asian Earth Sciences 37, 438-451, doi: 10.1016/j.jseaes.2009.11.003. Patriat, P., Achache, J., 1984. India-Eurasia collision chronology has implications for crustal shortening and driving mechanism of plates. Nature 311, 615-621, doi:10.1038/311615a0. Peltzer, G., Tapponnier, P., 1988. Formation and evolution of strike-slip faults, rifts, and basins during the India-Asia collision: an experimental approach. Journal of Geophysical Research 93, 15, 085-15, 117, doi: 10.1029/JB093iB12p15085. Piper, J.D., Tatar, A.O., Gursoy, H., 1997. Deformational behaviour of continental lithosphere deduced from block rotations across the North Anatolian fault zone in Turkey. Earth and Planetary Science Letters 150, 191-203, doi: 10.1016/S0012-821X(97)00103-9. Replumaz, A., Tapponnier P., 2003. Reconstruction of the deformed collision zone between India and Asia by backward motion of lithospheric blocks. Journal of Geophysical Research v. 108, p. 2285, doi: 10.1029/2001JB000661. Rowley, D.B., 1996. Age of initiation of collision between India and Asia: a review of stratigraphic data. Earth and Planetary Science Letters 145, 1-13, doi: 10.1016/S0012-821X(96)00201-4. Royden, L.H., Burchfiel, B.C., King, R.W., Wang, E., Chen, Z.L., Shen, F., Liu, Y.P., 1997. Surface deformation and lower crustal flow in eastern Tibet. Science 276, 788-790, doi: 10.1126/science.276.5313.788. Royden, L.H., Burchfiel, B.C., Vander Hilst, R.D., 2008. The geological evolution of the Tibetan Plateau. Science 321 (5892), 1054-1058, doi: 10.1126/science.1155371. Sato, K., Liu, Y.Y., Zhu, Z.C., Yang, Z.Y., Otofuji, Y., 1999. Paleomagnetic study of Middle Cretaceous rocks from Yunlong, Western Yunnan, China: evidence of southward displaycement of Indochina. Earth and Planetary Science Letters 165, 1-15, doi: 10.1016/S0012-821X(98)00257-X. Sato, K., Liu, Y.Y., Zhu, Z.C., Yang, Z.Y., Otofuji, Y., 2001. Tertiary paleomagnetic data from northwestern Yunnan, China: futher evidence for large clockwise rotation of the Indochina block and its tectonic implications. Earth and Planetary Science Letters 185, 185-198, doi: 10.1016/S0012-821X(00)00377-0. Sato, K., Liu, Y.Y., Wang, Y.B., Yokoyama, M., Yoshioka, S., Yang, Z.Y., Otofuji, Y., 2007. Paleomagnetic study of Cretaceous rocks form Pu‟er, western Yunnan, China: Evidence of internal deformation of the Indochina block. Earth and Planetary Science Letters 258, 1-15, doi:10.1016/j.epsl.2007.02.043. Schwartz, S.Y., Van der Voo., R., 1983. Paleomagnetic evaluation of the orocline hypothesis in the central and southern Appalachians. Geophysical Research Letters 10, 505-508, doi: 10.1029/GL010i007p00505. Shi, X.B., Qiu, X.L., Liu, H.L., Chu, Z.Y., Xia, B., 2006. Cenozoic Cooling History of Lincang Granitoid Batholith in Western Yunnan: Evidence from Fission Track Data. Chinese Journal of Geophysics 49 (1), 129-137, doi: 10.1002/cjg2.820. Takemoto, K., Sato, S., Chanthavichith, K., Inthavong, T., Inokuchi, H., Fujihara, M., Zaman, H., Yang, Z., Yokoyama, M., Iwamoto, H., Otofuji, Y., 2009. Tectonic deformation of the Indochina Peninsula recorded in the Mesozoic palaeomagnetic results. Geophysical Journal of International 179, 97-111, doi: 10.1111/j.1365-246X.2009.04274.x. Tanaka, K., Mu, C., Sato, K., Takemoto, K., Miura, D., Liu, Y., Zaman, H., Yang, Z., Yokoyama, M., Iwamoto, H., Otofuji, Y., 2008. Tectonic deformation around the eastern Himalayan syntaxis: Constraints from the Cretaceous palaeomagnetic data of the Shan-Thai Block. Geophysical Journal of International 175, 713-728, Page 19 of 48 doi: 10.1111/j.1365-246X.2008.03885.x.

Ac

ce

pt e

d

M

an

us

cr

ip t

Tang, Y., Yin, F.G., Wang, L.Q., Wang, D.B., Liao, S.Y., Sun, Z.M., Sun, J., 2013. Structural characterization and geochronological constraints on sinistral strike-slip shearing along the southern segment of Chongshan shear zone, western Yunnan (in Chinese with English abstract). Acta Petrologica Sinica 29 (4), 1311-1324. Tapponnier, P., Peltzer, G., Le Dain, A.Y., Armijo, R., Cobbold, P., 1982. Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine. Geology 10, 611-616, doi: 10.1130/0091-7613(1982)10 <611:PETIAN>2.0.CO;2. Tong, Y.B., Yang, Z.Y., Zheng, L.D., Xu, Y.L., Wang, H., Gao, L., Hu, X.Z., 2013. Internal crustal deformation in the northern part of Shan-Thai Block: New evidence from paleomagnetic results of Cretaceous and Paleogene redbeds. Tectonophysics 608, 1138-1158, doi: 10.1016/j.tecto.2013.06.031. Tong, Y.B., Yang, Z.Y., Wang, H., Zhang, X.D., An, C.Z., Xu, Y.C., Zhao, Y., 2014. The Creatceous paleomagnetic results from the central part of the Simao Terrane in the southwest part of China and its tectonic implications (in Chinese with English abstract). Chinese Journal Geophysics 57(1), 179-198, doi: 10.6038/cjg20140116. Van der Voo, R., 1990. Phanerozoic paleomagnetic poles from Europe and North America and compareisons with continental reconstructions. Reviews of Geophysics 28, 167-206, doi: 10.1029/RG028i002p00167. Van Hinsbergen, D.J.J., Kapp, P., Dupont-Nivet, G., Lippert, P.C., DeCelles, P.G., Torsvik, T.H., 2011. Restoration of Cenozoic deformation in Asia and the size of Greater India. Tectonics 30, TC5003, doi: 10.1029/2011TC002908. Vilotte J.P., Madariaga, R., Daignieres, M., Zienkiewicz, O., 1986. Numerical study of continental collision: Influence of buoyancy forces and an initial inclusion. Geophys. Geophysical Journal International 84 (2), 279-310, doi: 10.1111/j.1365-246X.1986.tb04357.x. Wang, E.C., Burchfiel, B.C., 2000. Late Cenozoic to Holocene deformation in southwestern Sichuan and adjacent Yunnan, China, and its role in formation of the southeastern part of the Tibetan Plateau. Geological Society of America Bulletin 112, 413-423, doi: 10.1130/0016-7606(2000)112<413:LCTHDI> 2.0.CO;2. Wang, G., Wan, J., Wang, E., Zheng, D., Li, F., 2008. Late Cenozoic to recent transtensional deformation across the southern part of the Gaoligong shear zone between the Indian plate and SE margin of the Tibetan plateau and its tectonic origin. Tectonophysics 460, 1-20. Wang, J.H., Yin, A., Harrison, T.M., Grove, M., Zhang, Y.Q., Xie, G.H., 2001. A tectonic model for Cenozoic igneous activities in the eastern Indo-Asian collision zone. Earth and Planetary Science Letters 188, 123-133, doi: 10.1016/ S0012-821X(01)00315-6. Wang, Y., Fan, W., Zhang, Y., Peng, T.P., Chen, X.Y., Xu Y.G., 2006. Kinematics and 40Ar/39Ar geochronology of the Gaoligong and Chongshan shear systems, western Yunnan, China: Implications for early Oligocene tectonic extrusion of SE Asia. Tectonophysics 418 (3), 235-254, doi: 10.1016/j.tecto.2006.02.005. Xu, Z.Q., Ji, S.C., Cai, Z.H., Zeng, L.S., Geng, Q.R., Cao, H., 2012. Kinematics and dynamics of the Namche Barwa Syntaxis, eastern Himalaya: Constraints from deformation, fabrics and geochronology. Gondwana Research 21 (19-36), doi: 10.1016/j.gr.2011.06.010. Yang, Z.D., 1996. Thrust-imbricate structure and nappe of Lincang Granite (in Chinese with English abstract). Scientia Geological Sinica 31 (2), 130-139. Yang, Z.Y., Besse, J., 1993. Paleomagnetic study on Permain and Mesozoic sedimentary rocks from North Thailand supports the extrusion model for Indochina. Earth and Planetary Science Letters 117, 525-552, doi: 10.1016/0012-821X (93) 90101-E. Yang, Z., Besse, J., Sutheetorn, V., Bassoullt, J.P., Fontaine, H., Buffeteau, E., 1995. Jurassic and Cretaceous paleomagnetic data for Indochina: Paleogeographic evolution and deformation history of South Eastern Asia. Earth and Planetary Science Letters 136:325-341. Yang, Z.Y., Besse, J., Sun, Z.M., Zhao, Y., 1998. Tertiary squeenz-out of the Indochina block and lithospheric evolution of the Qinghai-Tibetan plateau (in Chinese with English abstract). Acta Geologica Sinica 72 (2), 112-125. Yang, Z.Y., Sun, Z.M., Ma, X.H., Yin, J.Y., Otofuji, Y., 2001a. Paleomagnetic study of the Early Tertiary on both Sides of the Red River Fault and its geological implications (in Chinese with English abstract). Acta Geologica Sinica 75, 35-44. Yang, Z.Y., Yin, J.Y., Sun, Z.M., Otofuji, Y., Sato, K., 2001b. Discrepant Cretaceous paleomagnetic poles between Eastern China and Indochina: a consequence of the Page 20 of 48 extrusion of Indochina. Tectonophysics 334, 101-113, doi: 10.1016/S0040-1951(01)00061-0.

pt e

d

M

an

us

cr

ip t

Yin, A., Harrison, T.M., 2000. Geologic evolution of the Himalayan-Tibetan orogen. Annual Review of Earth and Planetary Sciences 28 (1), 211-280, doi: 10.1146/annurev.earth.28.1.211. Zhang, B., Zhang, J.J., Zhong, D.L., 2010a. Structure, kinematics and ages of transpression during strain partitioning in the Chongshan shear zone, western Yunnna, China. Journal of Structural Geology 32, 445-463, doi: 10.1016/j.jsg.2010.02.001. Zhang, P.Z., Shen, Z.K., Wang, M., Gan, W.J., Bürgmann, R., Molnar, P., Wang, Q., Niu, Z.J., Sun, J.Z., Wu, J.C., Sun, H.R., You, X.Z., 2004. Continuous deformation of the Tibetan Plateau from global positioning system data. Geology 32, 809-812, doi: 10.1130/G20554.1. Zhang, H.F., Tong, Y.B., Wang, H., Yang, Z.Y., 2012. Early Cretaceous Paleomagnetic results from Simao of Indochina Block and its tectonic implications (in Chinese with English abstract). Acta Geologica Sinica 86 (6), 923–939. Zhang, Z.M., Zhao, G.C., Santosh, M., Wang, J.L., Dong, X., Liou, J.G., 2010b. Two-stages of granulite-facies metamorphism in the eastern Himalayan syntaxis, south Tibet: petrology, zircon geochronology and implications for the subduction of Neo-Tethys and the Indian continent beneath Asia. Journal of Metamorphic Geology 28, 719-733, doi: 10.1111/j.1525-1314.2010.00885.x. Zhong, K.H., Liu, Z.C., Shu, L.S., Li, F.Y., Shi, Y.S., 2004. The Cenozoic strike-slip kinematics of the Lancangjiang fault zone (in Chinese with English abstract). Geological Review 50 (1), 1-8. Zhou, J.Y., Wang, J.H., Yin, A., Horton, B.K., Spurlin, M.S., 2003. Sedimentology and tectonic significance of Paleogene coarse clastic rocks in eastern Tibet (in Chinese with English abstract). Acta Geologica Sinica 77 (2), 262-272. Zijderveld, J.D.A.,1967. Ac demagnetizeation of rocks: analysis of results, in : D.W. Collinson, K.M. Creer, S.K. Runcorn (Eds), Methods in Paleomagnetism. Elsevier, Amsterdam 254-286.

Ac

ce

Figure 1

Page 21 of 48

Page 22 of 48

d

pt e

ce

Ac M

an

cr

us

ip t

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 2

Page 23 of 48

ip t Ac

ce

pt e

d

M

an

us

cr

Figure 3

Page 24 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 4

Page 25 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 5

Page 26 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 6

Page 27 of 48

ip t Ac

ce

pt e

d

M

an

us

cr

Figure 7

Page 28 of 48

ip t Ac

ce

pt e

d

M

an

us

cr

Figure 8

Page 29 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 9

Page 30 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 10

Page 31 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 11

Page 32 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 12

Page 33 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 13

Page 34 of 48

ip t Ac

ce

pt e

d

M

an

us

cr

Figure 14

Page 35 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Figure 15

Page 36 of 48

Paleomagnetic studies reveal three periods of clockwise rotation in Jinggu area Large scale clockwise rotation occured between 27 and 20 Ma in Jinggu area Compressional stress and Block extrusion together formed the Lanping-Simao Arc

Table Captions

ip t

Table 1. Paleomagnetic Results From the Cretaceous and Paleogene Formations.

Ac

ce pt

ed

M

an

us

cr

Note: Lat. (N), latitude of site; Lon. (E), longitude of site; N/n, number of samples used to calculate mean direction; Dg, Ig, Ds, Is, declination and inclination in geographic and stratigraphic coordinates, respectively; k, the best estimate of the precision parameter; α95, the radius within which the mean direction lies with 95% confidence. Units: degrees. The * in front of the site indicates that these sites were not used in the calculation of the mean direction for HTC. K1: Early Cretaceous; K2: CLNS; P: Paleocene; E-O: Eocene-Oligocene. The fold test was conducted for each of the Sub-areas A (JY1-10, JP17-21), B (JE1-6, JP1-10), C (JP11-14, JY11-15), D (JP15-16, 22-41) and E (JP42-51). For Sub-area A, the fold test is positive at the 99% confidence level according to the McElhinny method, Ks/Kg = 4.11＞F(12,12) = 2.69, and the McFadden (1990) method at the 95% confidence level (ζ1 (in situ) = 3.62, ζ1 (tilt corrected) = 1.90, ζc = 3.09); For Sub-area B, the fold test is positive at the 99% confidence level according to the McElhinny method, Ks/Kg = 5.61＞ F(10,10) = 4.85, and the McFadden (1990) method at the 95% confidence level (ζ 1(in situ) = 3.59, ζ1(tilt corrected) = 0.91, ζc = 2.86); For Sub-area C, the fold test is positive at the 99% confidence level according to the McElhinny method, Ks/Kg = 5.00＞F(16,16) = 3.37, and inconclusive at the 99% confidence level according to the McFadden (1990) method (ζ1(in situ) = 1.81, ζ1(tilt corrected) = 1.06, ζc = 4.85); For Sub-area D, the fold test is positive at the 99% confidence level according to the McElhinny method, Ks/Kg = 7.57＞F(30,30) = 2.38, and the McFadden (1990) method at the 95% confidence level (ζ1(in situ) = 4.99, ζ1(tilt corrected) = 0.55, ζc = 4.86); for Sub-area E, the fold test is positive at the 99% confidence level according to the McElhinny method, Ks/Kg = 6.92＞F(16,16) = 3.37, and the McFadden (1990) method at the 95% confidence level (ζ1(in situ) = 8.07, ζ1(tilt corrected) = 2.61, ζc = 4.85). Table 2. Paleomagnetic results from the Miocene Formation. Note: D, I declination and inclination, respectively; α95, the radius within which the mean direction lies with 95% confidence. Unit: degree. N (n), number of sites (samples) used in statistics. Table 3. Cretaceous and Cenozoic paleomagnetic directions and corresponding poles for the Shan-Thai Block, Indochina Block, Baoshan and Tengchong Terranes.

Page 37 of 48

Ac

ce pt

ed

M

an

us

cr

ip t

Note: Long(E), longitude; Lat(N), latitude; Age: K1, Early Cretaceous; K2, CLNS; K3, Late Cretaceous; P, Paleocene; E, Eocene; O, Oligocene; M: Miocene. N (n), number of sites (samples) used in paleomagnetic statistics. D (°) and I (°), declination and inclination, respectively; α95 and A95 are radii of the cone of 95% confidence about the mean direction and the VGP, respectively. Rotation and latitudinal differences are evaluated by comparison between the observed paleomagnetic result and that expected from the Eurasia (Besse and Courtillot, 2002). Minus/ Plus, Counterclockwise/ Clockwise Rotation. S0 and S are the reference strike and arithmetic average strikes of tectonic lines calculated for the linear regression calculation (Schwartz and Van der Voo, 1983), respectively. Data reliability criteria: 1, age of rocks; 2, statistic precision N >24, k >10°,α95 <16.0°; 3, detailed demagnetization and isolation of magnetic components; 4, positive field stability tests; 5, structural controls; 6, presence of reversals; 7, lack of remagnetization (Van der Voo, 1990).

Page 38 of 48

Figure captions

an

us

cr

ip t

Fig. 1. (a) Simplified tectonic map of Southeast Asia. The blue rectangle indicates the position of b. (b) Schematic map of the Lanping–Simao Terrane and the surrounding area. The black rectangle represents the sampling locality for this study, modified from Leloup et al. (1995) and Tong et al. (2013). NBS: Namche–Barwa Syntaxis; GLSZ: Gaoligong Shear Zone; CSSZ: Chongshan Shear Zone; CM: Middle segment of CSSZ; CS: Southern segment of CSSZ; JSRF: Jinsha-Red River Fault; DBPF: Dien Bien Phu Fault; WCSF: Wangchao shear zone; TPSZ: Three Pagodas shear zone; XXH-XJ F: Xianshuihe–Xiaojiang Fault; NTF: Nanting River Fault; BKB: Bu Khang block.

ed

M

Fig. 2. Simplified geological map of the study area. Sampling sites are indicated by closed circles. Strike/dip orientations of strata are shown in the insets. Yellow squares represent the sampling sites of Chen et al. (1995). The study area (JY, JE and JP) are divided into five sub-areas (A, B, C, D and E) separated by different faults.

ce pt

Fig. 3. Isothermal remanent magnetization acquisition and reverse field demagnetization curves of representative samples from the JP, JY, and JE sections.

Fig. 4. Three-component IRM thermal demagnetization curves of representative samples from the JP, JY, and JE sections.

Ac

Fig. 5. Three-component IRM thermal demagnetization curves of representative samples from the JN section.

Fig. 6. Isothermal remanent magnetization acquisition and reverse-field demagnetization curves of representative samples from the JN section.

Fig. 7. Stereonet projection of AMS in stratigraphic coordinates after tilt correction and plots of shape parameter (T) versus anisotropy degree (P) Jelinek, (1981). Flinn diagram (F/L) of magnetic fabrics for Cretaceous–Paleocene (a) and Miocene (d) rocks: k1, maximum; k2, intermediate; k3, minimum; L =k1/k2; F= k2/k3; P=exp{sqr[2

Page 39 of 48

×( (η1-ηm) 2 + (η2-ηm) 2 + (η3-ηm) 2)]}; T= (2η2-η1-η3)/ (η1-η3) (η1=In k1;η2=In k2;η3 =In k3;ηm= (η1 +η2 +η3) /3). Rose diagrams of AMS data for Cretaceous–Paleocene (b) and Miocene (e) rocks. The formation process of the AMS ellipsoid for Cretaceous–Paleocene (c) and Miocene (f) sections.

ip t

Fig. 8. Representative Zijderveld diagrams of thermal demagnetizations of NRM from the JY, JP, and JE sections (after tilt correction).

an

us

cr

Fig. 9. Equal-area projections of site-mean directions for the LTC (a, b), ITC (c, d), and HTC (e, f) before (IS) and after tilt (TC) corrections. Solid (open) symbols denote the lower (upper) hemisphere. Black stars represent the average direction of the section with circles of 95% confidence limit (shaded circle); N/n denotes the number of sampling sites/samples used to calculate the mean direction.

ed

M

Fig. 10. Equal-area projections of site-mean directions for the HTC before (IS) and after tilt (TC) corrections of different sections (The sub-area corresponding to Fig. 2). Solid (open) symbols denote the lower (upper) hemisphere. Black stars represent the average direction of the section with circles of 95% confidence limit (shaded circle); N denotes the number of sampling sites used to calculate the mean direction.

ce pt

Fig. 11. Representative Zijderveld diagrams of thermal demagnetization of NRM from the Sanhaogou Formation (after tilt correction).

Ac

Fig. 12. Equal-area projections of site-mean directions for LTC (a, b) and HTC (c, d) before (IS) and after tilt (TC) corrections. Solid (open) symbols denote the lower (upper) hemisphere. Black stars represent the average direction of the section with circles of 95% confidence limit (shaded circle); n denotes the number of samples used to calculate the mean direction.

Fig. 13. (a) Summary of paleomagnetic data from the Jinggu area. The numbers on the X axis correspond to those in Table 3. (b) Summary of paleomagnetic data from the Shan–Thai Block. (c) Correlation of changes in the tectonic line in the Lanping–Simao Terrane and the tectonic rotation of each paleomagnetic sampling area. We chose the strike of the middle segment of the Red River Fault as the reference strike (S0 = 145°; Schwartz and Van der Voo, 1983; Tong et al., 2013, 2014); S is the arithmetic average strike of the paleomagnetic study area. R: correlation coefficient. JG: Jinggu; K1: Early Cretaceous; K2: middle Cretaceous; E-O: Eocene-Oligocene (38-29Ma); M: Miocene; LP: Lanping; WS: Weishan; ZY:

Page 40 of 48

Zhenyuan; ZW: Zhengwan; PE: Puer; YP: Yongping; YL: Yunlong; JD: Jingdong; WY: Wuyin; DDG: Dadugang; MB: Mangbang; Mla: Mengla; Mlun: Menglun; BS: Baoshan; TC: Tengchong.

us

cr

ip t

Fig. 14. (a) Simplified tectonic map of Southeast Asia. The solid square represents the position of b. (b) Geological sketch map of the CLCMB. NBS: Namche–Barwa Syntaxis; WF: Lincang West thrust fault; EF: Lincang East thrust fault; SF: Lancangjiang slip thrust fault; GLGS: Glaoligong Shear Zone; CSS: Chongshan Shear Zone; JSRF: Jinsha-Red River Fault; DBPF: Dien Bien Phu Fault; WCF: Wangchao Fault; TPSZ: Three Pagodas Fault; XXH-XJ F: Xianshuihe–Xiaojiang Fault; NTF: Nanting River Fault; BKB: Bu Khang block. (Modified from: Leloup et al., (1995); Yang, (1996); Tong et al., (2013)).

Ac

ce pt

ed

M

an

Fig. 15. Different stages of tectonic deformation in the Lanping–Simao, Tengchong, and Baoshan terranes. (a) No apparent differential clockwise rotation occurred in the Lanping–Simao Terrane prior to 40 Ma. (b) Thrusting in the CLCMB induced uplift of granite and provided rock fragments for the Mengla Group in the Jinggu Basin during 36–29 Ma, modified from Liu et al. (1998). (c) Between 40 and 30 Ma, the Tengchong Terrane experienced a 46° clockwise rotation under west to east compressive stress (gray arrows). At the same time, the Shan–Thai, Tengchong, Baoshan, and Indochina blocks experienced a clockwise rotation of about 20° from 36–21 Ma. Thrusting occurred in the south CLCMB. The Baoshan Terrane and the CLCMB experienced southward displacement along the GLSZ and CSSZ. (d) During the period between 26 and 15 Ma, the sinusoidal shape of the CLCMB formed under the influence of west to east compressive stress (gray arrows) and all blocks (Shan–Thai, Tengchong, Baoshan, and Indochina) underwent coherent southward displacement along the Red River Fault (possibly as early as 36 Ma). (e) Paleoposition of the significantly-rotated zone (paleomagnetically determined) with the NNE indentation of the Indian Plate into Asia. This paleomagnetically-determined clockwise-rotated zone „„S” is now located at 23.5°N, 101°E (Jinggu Basin). Prior to the India–Asia collision, its paleoposition „„s” is thought to have been at 30°N, 94°E. The picture shows the reconstructed positions of two points (open stars and dots) on the India plate with respect to the Eurasia plate since 48 Ma (Molnar and Stock, 2009). The red star indicates the position of the Eastern Himalayan syntaxis, which shifts NNE along the longitudinal zone between 86°E and 96°E. At the same time, significant clockwise rotation occurred in a swath between these longitudes, marked by yellow rectangles, modified from Otofuji et al. (2010). (f and g) After about 20 Ma, a significant small-scale clockwise rotation occurred in the Simao Terrane, modified from Tanaka et al. (2008). GLSZ: Gaoligong Shear Zone; CSSZ: Chongshan Shear Zone; JSRF: Jinsha-Red River Fault; DBPF: Dien Bien Phu Fault; WCSF: Wangchao shear zone; TPSZ: Three Pagodas Fault; NTF: Nanting River Fault; SZ: Sagaing Fault.

Page 41 of 48

Page 42 of 48

ed

ce pt

Ac

us

an

M

cr

ip t

Table 1. Paleomagnetic Results From the Cretaceous and Paleogene Formations. Locality Site name

Lat.(N)

In situ

Tilt corrected

Bedding

Lon.(E)

n/N

D(°) I(°)

D(°) I(°)

k

α95 (°)

Strike(°) Dip(°)

Sub-area A (JY1-10, JP17-21) JY01(K2)

23°22'30.0"

100°38'19.0"

0/11

-

-

-

-

356/35

*

JY02(K2)

23°22'30.0"

100°38'19.0"

0/10

-

-

-

-

356/35

*

JY03(K2)

23°22'7.1"

100°38'8.9"

0/11

-

-

-

-

7/25

JY04(K2)

23°22'7.4"

100°38'6.5"

9/12

117.2 45.6

89.9 56.8

81.3

5.7

347/24

*

23°22'7.4"

100°38'6.5"

3/12

125.3 56.9

93.6 65.7

27.5

24.0

353/19

JY05(K2)

ip t

*

JY06(K2)

23°21'32.8"

100°37'56.0"

0/10

-

-

-

-

292/48

*

JY07(K2)

23°21'21.4"

100°37'51.5"

8/12

69.4 46.0

51.2 43.7

13.2

15.8

328/20

*

JY08(K2)

23°21'16.6"

100°37'47.3"

0/10

-

-

-

-

328/36

*

JY09(K2)

23°21'16.7"

100°37'45.7"

2/10

103.4 20.7

80.8 36.7

11.8

81.0

341/42

JY10(K2)

23°21'16.7"

100°37'45.7"

8/13

90.6 23.8

58.6 43.9

89.2

5.9

322/48

JP17(K2)

23°19'42.0"

100°38'04.0"

7/9

95.1

86.5 42.7

62.0

7.7

207/44

JP18(K2)

23°19'51.0"

100°37'55.0"

8/11

80.6 16.5

65.2 40.2

44.0

9.2

213/36

JP19(K2)

23°19'51.0"

100°37'55.7"

7/9

95.0 17.3

81.5 47.4

127.8

5.4

213/36

JP20(K2)

23°17'58.0"

100°37'55.0"

11/14

78.1 -0.8

61.9 48.4

64.6

6.1

195/58

JP21(K2)

23°17'59.0"

100°37'55.0"

8/9

84.3 -3.9

76.6 42.2

36.9

9.2

195/50

90.4 14.6

63.9

7.6

us

M

an

2.8

cr

*

73.8 46.5

*

JE01(P)

23°30'16.0"

100°39'50.0"

3/15

49.9 77.8

67.5 46.7

54.9

16.8

75/32

*

JE02(P)

23°30'50.0"

100°39'50.0"

3/12

90.0 73.5

81.7 44.8

67.3

15.2

77/29

*

JE03(P)

100°40'6.0"

1/12

38.3 56.1

53.0 31.0

-

4.1

110/32

100°45'16.7"

4/12

112.5 67.5

92.7 37.4

14.6

24.9

76/33

100°45'0.9"

2/12

142.5 56.0

105.9 24.7

-

25.2

70/49

Site-mean

7

23°30'56.4"

ed

Sub-area B (JE1-6, JP1-10)

*

JE04(E-O)

*

JE05(E-O)

*

JE06(E-O)

23°30'50.5"

100°44'42.4"

0/12

-

-

-

-

79/35

ce pt

23°30'47.6"

23°30'48.8"

23°30'53.0"

100°40'02.0"

3/16

47.7 49.6

68.5 38.0

74.3

14.4

30/24

JP02(P)

23°30'47.0"

100°39'59.0"

0/12

-

-

-

-

10/27

*

JP03(P)

23°30'47.0"

100°39'59.1"

2/10

40.9 63.1

67.6 43.5

33.6

44.5

10/27

*

JP04(P)

23°30'47.0"

100°39'59.2"

1/9

41.2 53.6

59.6 38.4

-

6.1

10/23

23°30'03.0"

100°39'01.1"

11/15

75.5 38.8

72.6 42.5

200.4

3.2

206/5

23°30'03.0"

100°38'41.0"

10/11

77.9 25.9

76.4 35.6

69.0

5.9

182/10

23°30'03.0"

100°38'41.0"

10/12

75.8 25.3

73.2 50.1

56.7

8.1

172/25

JP08(K2)

23°30'03.0"

100°38'42.0"

6/11

73.7 25.0

63.5 38.3

27.8

14.8

210/21

JP09(K2)

23°30'15.0"

100°38'24.0"

9/12

78.8

6.0

63.6 49.2

36.9

8.1

194/50

*

23°30'15.0"

100°38'24.6"

2/12

76.9 -1.2

67.4 42.4

33.5

44.6

191/49

6

72.9 28.8

69.7 42.4

123.4

6.1

JP05(K2) JP06(K2) JP07(K2)

JP10(K2)

Ac

JP01(P) *

Site-mean

Sub-area C (JP11-14, JY11-15) JP11(K2)

23°30'20.0"

100°36'13.0"

5/11

92.2

3.2

84.2 51.4

141.8

6.4

195/50

JP12(K2)

23°30'20.0"

100°36'13.5"

6/14

92.4 -10.6

90.1 37.7

97.7

9.3

192/49

Page 43 of 48

23°32'13.0"

100°33'17.0"

5/8

57.9 53.0

84.9 50.5

46.6

13.6

65/21

JP14(K2)

23°32'13.0"

100°33'17.6"

11/13

69.9 38.2

88.4 33.5

33.0

8.1

68/26

JY11(K2)

23°29'56.0"

100°35'02.0"

4/12

66.2 43.9

56.6 47.6

472.4

4.2

310/10

JY12(K2)

23°30'0.00"

100°35'09.0"

11/12

75.2 57.2

61.0 54.4

46.4

6.8

354/10

JY13(K2)

23°31'29.0"

100°34'43.0"

11/13

49.7 52.9

70.0 46.6

99.6

4.6

130/18

JY14(K2)

23°31'0.90"

100°34'40.0"

11/12

52.8 57.8

69.2 47.5

202.2

3.2

112/16

JY15(K2)

23°30'50.0"

100°34'53.0"

12/12

69.9 47.5

75.5 29.7

55.2

5.9

94/19

9

72.4 39.9

76.2 44.9

45.0

7.8

Site-mean

Sub-area D (JP15-16, 22-41)

ip t

JP13(K2)

23°32'51.0"

100°31'20.0"

9/10

25.0 59.9

87.1 42.9

76.7

7.7

40/45

JP16(K2)

23°32'51.0"

100°31'20.3"

1/9

19.5 23.5

44.9 27.1

-

5.5

36/50

*

JP22(K1)

23°26'26.0"

100°26'24.0"

-

-

-

-

-

178/90

JP23(K1)

23°26'29.0"

100°26'34.0"

6/8

332.6 62.1

68.4 28.1

51.1

9.5

5/75

JP24(K2)

23°26'30.0"

100°26'39.0"

8/16

311.3 70.1

JP25(K2)

23°26'41.0"

100°27'07.0"

13/14

10.5 69.6

JP26(K2)

23°26'46.0"

100°27'08.0"

7/11

30.7 69.3

JP27(K2)

23°26'48.0"

100°27'08.0"

13/13

20.9 66.7

JP28(K2)

23°26'55.0"

100°27'18.0"

16/16

39.3 58.5

JP29(K2)

23°26'50.0"

100°27'20.0"

8/10

*

JP30(K2)

23°26'50.0"

100°27'20.0"

3/11

JP31(K2)

23°26'56.0"

100°27'33.0"

8/11

JP32(K2)

23°26'56.0"

100°27'33.0"

JP33(K2)

23°26'54.0"

JP34(K2)

28.9

10.5

7/56

76.3 51.5

48.3

6.0

20/37

77.2 50.2

25.5

12.2

20/31

70.4 51.6

35.4

7.1

20/31

62.1 48.8

56.2

5.0

21/19

55.5 59.0

84.8 47.5

156.1

4.4

43/24

72.5 57.8

96.1 39.7

25.9

24.7

44/28

59.0 47.0

75.0 38.6

80.2

6.2

41/19

9/12

67.7 48.5

82.6 37.6

37.9

8.5

41/19

100°27'35.0"

12/14

74.7 42.1

79.7 40.2

54.2

5.9

59/6

23°26'55.0"

100°27'39.0"

10/11

72.6 41.0

77.4 39.4

28.0

9.3

59/6

ed

an

79.9 49.3

M

us

cr

JP15(K2) *

23°26'47.0"

100°27'53.0"

5/11

64.3 40.4

66.5 42.1

41.5

12.0

101/3

JP36(K2)

23°27'55.0"

100°29'18.0"

-

-

-

-

-

218/15

*

JP37(K2)

23°27'55.0"

100°29'20.0"

3/8

88.3 36.3

79.0 47.1

7.8

47.4

218/15

*

JP38(K2)

23°27'55.0"

100°29'20.0"

7/12

76.1 40.3

63.5 48.3

11.9

18.2

218/15

JP39(K2)

23°27'57.0"

100°29'20.0"

5/10

81.4 33.5

68.0 45.7

34.5

13.2

218/20

JP40(K2)

23°28'03.0"

100°29'31.0"

5/10

85.1 47.9

82.9 47.6

57.6

10.2

270/2

JP41(K2)

23°28'02.0"

100°29'29.0"

11/17

77.3 46.0

75.3 45.5

34.5

7.9

270/2

16

54.8 58.4

75.8 44.4

100.3

3.7

Ac

Site-mean

ce pt

JP35(K2) *

Sub-area E (JP42-51) JP42(K2)

23°30'31.0"

100°41'18.0"

4/10

87.0 -3.7

79.9 20.3

269.5

5.6

237/51

JP43(K2)

23°25'56.0"

100°17'33.0"

4/9

74.9

9.2

47.5 42.8

28.7

17.4

210/59

JP44(K2)

23°26'12.0"

100°17'14.0"

8/10

86.0

2.0

73.9 41.8

78.2

6.3

206/48

JP45(K2)

23°26'12.0"

100°17'15.0"

7/11

84.2

2.0

63.0 53.5

36.1

10.2

200/61

JP46(K2)

23°27'03.0"

100°15'56.0"

8/10

82.1 62.7

92.9 27.0

119.8

5.1

14/37

JP47(K2)

23°27'03.0"

100°15'56.0"

9/9

78.6 65.0

92.0 29.6

61.2

6.6

14/37

JP48(K2)

23°27'03.0"

100°15'56.0"

7/10

77.0 69.6

92.9 34.2

69.8

7.3

14/37

JP49(K2)

23°27'03.0"

100°15'56.0"

10/11

81.5 67.7

94.2 31.9

69.7

5.8

14/37

JP50(K2)

23°27'04.0"

100°15'56.0"

14/15

74.0 67.3

90.1 39.3

114.5

3.7

15/30

*

Page 44 of 48

JP51(K2)

23°27'04.0"

100°15'56.0"

Site-mean Grand Mean

23.5°

100.4°

8/10

62.6 71.0

89.5 40.9

216.1

3.8

9

81.7 46.3

86.3 35.7

41.0

8.1

47

73.4 42.8

77.0 43.0

54.0

2.9

17/34

Table 2. Paleomagnetic results from the Miocene Formation. Temperature span

n

for direction

D(°) I(°)

D(°) I(°)

In situ

Tilt corrected

calculation Sites with 1 sample T340-T530

1

20.6 17.3

8.8 26.2

JN7-5

T400-T540

1

28.4 31.9

6.3 42.3

JN9-8

T400-T510

1

17.4 23.5

2.7 30.2

JN10-7

T400-T510

1

34.1 16.0

JN21-9

T350-T500

1

240.3 -22.8

JN22-5

T330-T400

1

233.8 -13.9

JN26-9

T200-T450

1

37.1 35.0

JN27-1

T300-T450

1

36.9 28.0

31.6 33.5

T380-T480

JN8-4

T400-T540

JN8-5

T300-T480

JN8-6

T400-T480 4

ed

Site-mean of JN8

178/30

5.3

178/30

6.3

177/29

23.0 31.5

4.8

177/29

220.7 -47.9

12.1

188/36

220.0 -37.2

4.7

203/29

7.3 46.1

4.1

185/35

13.6 40.7

3.7

185/35

5.8 42.3

6.7

44.5 21.8

27.3 39.8

7.5

36.4 35.1

8.5 46.2

4.4

28.7 21.2

12.8 31.0

5.4

35.4 28.0

13.8 40.1

11.1

us

an

JN8-2

Strike(°) Dip(°)

8.1

M

sample ≥ 2

JN15-7

T370-T500

25.0 27.0

4.3 33.2

8.8

JN15-8

T340-T500

32.2 28.5

9.1

38.4

4.1

28.6 27.8

6.6

35.8

-

T370-T450

30.1 26.3

15.5 26.2

2.9

T370-T450

38.0 17.3

27.4 22.4

5.2

T400-T530

28.2 15.2

20.0 15.7

4.1

T300-T400

42.1 27.2

25.3 32.8

2.9

T230-T370

42.2 27.1

25.4 32.7

3.8

JN16-11 JN16-12 JN16-2 JN16-5

Ac

JN16-7

ce pt

Site-mean of JN15

Site-mean of JN16

2

5

36.0 22.7

22.6 26.0

8.0

JN17-6

T260-T370

38.4 28.3

21.3 31.9

1.8

JN17-7

T370-T450

32.2 29.2

15.5 29.6

2.6

JN17-8

T200-T400

48.7 23.1

33.9 32.5

1.5

JN17-9

T230-T400

27.7 33.5

9.0 31.1

1.3

JN17-12

T340-T450

21.5 25.7

8.7 21.6

4.6

33.8 28.3

17.4 29.7

9.6

Site-mean of JN17

5

Bedding

cr

JN5-9

α95 (°)

ip t

Sample Number

JN23-1

T370-T560

31.9 34.4

7.6 46.0

1.4

JN23-2

T340-T450

33.3 33.5

9.8 45.9

1.1

JN23-3

T200-T370

30.1 28.5

10.6 40.3

1.2

JN23-5

T200-T400

25.8 34.7

1.7 43.2

2.3

JN23-8

T340-T450

24.4 24.3

8.1 34.0

3.3

184/33

185/35

203/29

203/29

Page 45 of 48

JN23-9

T260-T370

27.6 33.4

4.4 43.1

1.0

JN23-10

T300-T400

35.8 26.8

17.4 41.6

1.9

JN23-11

T260-T400

22.3 29.0

3.0 36.8

2.7

JN23-12

T260-T400

27.2 25.4

9.9 36.2

2.9

28.7 30.1

8.1 40.9

3.6

Site-mean of JN23

9

JN24-1

T260-T450

18.2 25.1

2.0 31.6

2.5

JN24-5

T250-T400

31.9 24.7

15.0 38.0

1.5

25.1 25.1

8.2

JN25-2

T300-T500

2

24.3 33.0

358.1 37.1

35.0

JN25-7

T340-T450

41.5 28.9

16.0 44.2

JN25-10

T340-T500

17.9 20.1

3.0

23.6 35.2

-

2.1 4.4

3

27.7 27.7

5.2

19.6

Site-mean direction

N=7

30.8 27.2

11.9 34.8

5.7

n = 38

32.3 26.9

13.7 36.0

3.3

185/36

Ac

ce pt

ed

M

an

us

cr

Site-mean of JN25

Sample-level mean direction

178/30

3.3

ip t

Site-mean of JN24

178/30

Page 46 of 48

1 2

Table 3. Cretaceous and Cenozoic paleomagnetic directions and corresponding poles for the Shan-Thai Block, Indochina Block, Baoshan and Tengchong Terranes. Observed direction

Lat.(N)

Long.(E)

Age

N(n)

D(°)

I(°)

Pole position

α95 (°)

Lat.(N)

Long.(E)

Rotation

S

S0-S

A95(°)

Reliability 1

2

3

4

5

6

7

Q

99.3

E

9(52)

86.1

39.8

11.2

15.0

169.7

10.9

75.6±9.2

188.0

-43.0

+

+

+

+

+

5

S

25.8

99.4

K2

20(160)

40.2

49.9

3.9

56.0

171.3

4.0

29.2±6.5

154.0

-9.0

+

+

+

+

+

5

Sa

25.8

99.4

K2

29(233)

38.3

50.7

3.4

56.7

170.1

4.0

28.4±6.5

154.0

-9.0

+

+

+

+

+

5

Ya

25.5

99.5

K2

12(57)

42.0

51.1

15.7

50.9

167.3

20.6

35.2±18.9

155.0

-10.0

Fun

25.3

100.4

K3

18(177)

64.3

48.5

4.7

33.5

170.5

5.0

55.3±6.3

75.0

-27.0

25.1

100.1

K2

7(45)

15.4

44.8

4.6

76.2

184.2

4.6

6.1±6.6

75.0

70.0

24.5

100.8

K2

13(102)

8.3

48.8

7.7

81.0

153.7

8.2

0.8±8.8

155.0

20.0

101.0

K2

7(55)

61.8

46.1

8.1

38.0

173.2

8.3

47.8±8.6

167.0

23.9

101.1

K2

8(71)

52.4

45.5

6.3

42.9

175.9

6.4

43.4±7.6

23.5

100.8

38-29Ma

6

73.1

39.9

11.8

23.2

176.0

12.2

66.4±10.1

7(32)

84.7

38.9

7.6

13.2

172.2

7.0

8.9

23.5

100.8

38-29Ma

23.4

100.9

K2

7(39)

79.4

43.3

9.1

18.9

170.0

23.5

100.4

K2

48(397)

77.0

43.0

2.9

20.8

171.3

23.4

100.4

K1

3(10)

84.4

39.6

17.8

13.6

171.5

23.5

100.7

M

(38)

13.7

36.0

3.3

76.8

203.6

23.5

100.7

M

(29)

21.1

35.5

7.5

70.0

23.0

101.0

K2

25(212)

59.9

45.2

5.1

22.7

101.1

K2

13(183)

46.2

46.6

5.6

22.8

100.9

K1

11(108)

51.8

47.9

6.9

22.4

101.0

K1

12(107)

21.8

101.6

P-E

6(36)

21.5

101.5

38-29Ma

17(155)

+

+

+

+

5

+

+

+

+

+

+

6

T

+

+

+

+

+

5

T

cr +

+

+

+

+

5

Tan

-22.0

+

+

+

+

+

5

Tan

+

+

5

Zh

+

4

Ya

+

5

Ch

+

4

+

5

us

10.0

-22.0

+

+

+

191.0

-46.0

+

+

+

77.9±6.4

191.0

-46.0

+

+

+

70.6±9.1

191.0

-46.0

+

+

+

+

+

M

(Mengla Group)

+

167.0

an

(Mengla Group)

ip t

26.5

68.0±5.9

191.0

-46.0

+

16.5

69.0±13.3

191.0

-46.0

+

2.9

8.2±3.2

170.0

-25.0

+

197.8

6.6

15.7±5.6

170.0

-25.0

35.8

173.1

5.6

51.3±7.1

160.0

48.2

172.0

5.8

37.3±7.3

42.4

170.1

7.8

ce pt

ed

2.8

+

+

Huang

+

+

+

4

+

+

+

+

5

+

+

+

+

+

5

Ch

-15.0

+

+

+

+

+

+

6

Sa

160.0

-15.0

+

+

+

+

+

5

Zh

37.7±7.0

166.0

-21.0

+

+

+

+

+

6

Ko

+

+

5

Ko

+

5

To

+

Ch

64.1

48.1

7.3

32.6

169.8

7.7

48.8±6.8

140.0

5.0

+

+

+

43.5

23.0

13.4

46.4

196.7

12.2

35.7±9.6

112.0

33.0

+

+

+

41.8

23.8

5.8

48.4

194.8

5.8

36.4±5.4

112.0

33.0

+

+

+

+

+

5

To

46.9

42.2

7.7

45.3

177.2

8.5

33.6±7.2

112.0

33.0

+

+

+

+

+

5

To

33.2

30.9

8.2

56.3

195.8

8.2

26.2±7.8

112.0

33.0

+

+

+

+

+

+

6

To

19(200)

46.2

45.9

11.0

48.9

172.9

12.6

29.9±10.7

112.0

33.0

+

+

+

+

+

+

6

To

4(29)

50.5

31.0

6.4

42.2

188.5

6.8

41.7±7.5

112.0

33.0

+

+

+

+

+

5

To

11

51.7

33.4

8.7

41.3

185.2

8.6

43.6±7.2

112.0

33.0

+

+

+

+

+

+

6

Ya

112.0

33.0

+

+

+

+

+

5

Huang

(Mengla Group)

+

101.6

K1

14(123)

21.9

101.2

K3

6(73)

21.9

101.2

K1

21.8

101.6

K2

21.5

101.7

E

21.6

101.4

K3

10(49)

60.8

37.8

7.6

33.7

179.3

8.2

52.1±7.9

16.8

103.5

K1

8(42)

31.4

27.1

9.4

59.7

193.7

7.5

16.6±6.1

+

+

+

+

+

5

Cha

16.5

103.3

K1

14(160)

31.8

38.3

5.7

59.6

178.7

5.2

17.0±4.6

+

+

+

+

+

5

Cha

15.8

101.9

K1

10(87)

32.0

38.2

1.0

59.4

177.4

5.0

17.1±4.5

+

+

+

+

4

Ya

26.0

98.8

30Ma

(12)

42.2

47.0

7.8

52.6

175.6

8.1

35.0±7.5

+

+

4

Ac

21.4

+

+

Page 47 of 48

Ko

26.0

98.7

30Ma

(6)

41.5

46.6

7.2

53.1

176.2

7.4

34.4±6.9

+

+

+

+

4

Kor

26.0

98.7

40Ma

(6)

89.8

35.1

11.8

8.5

171.3

10.3

80.8±8.5

+

+

+

+

4

Kor

K1

130Ma

75.8

192.9

2.8

K2

100Ma

81.7

180.1

6.7

K3

80 Ma

81.4

206.1

5.9

P

60Ma

81.1

190.5

2.9

P-E

50Ma

80.9

164.4

3.4

E

40 Ma

81.3

162.4

3.3

E-O

30 Ma

82.8

158.1

3.8

M

20Ma

84.0

154.8

2.7

ip t

Besse

cr

3

Ac

ce pt

ed

M

an

us

4

Page 48 of 48