- Email: [email protected]
Resolving the age of the Mesozoic Kuar Bet Beds (Kachchh, Gujarat, India): A reinvestigation of palaeobotanical and palynological assemblages
Journal of Asian Earth Sciences 30 (2007) 457–463 www.elsevier.com/locate/jaes
Resolving the age of the Mesozoic Kuar Bet Beds (Kachchh, Gujarat, India): A reinvestigation of palaeobotanical and palynological assemblages Brajendra Nath Jana a,¤, Jason Hilton b a
b
Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226 007, India School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK Received 16 October 2006; accepted 30 November 2006
Abstract Within the Mesozoic sedimentary sequences of India the age of the Kuar Bet Beds in Kachchh (Gujarat Province) has been hotly contested, with faunal evidence suggesting a Bathonian (Middle Jurassic) age, based on ammonite and foraminiferal occurrences, and palaeobotanical evidence suggesting an Early Cretaceous age, based on the presence of the index fossil Onychiopsis sp. cf. psilotoides (Stokes and Webb) Ward. Previously reported palynological evidence has documented numerous angiosperm pollen taxa, lending further support to an Early Cretaceous age. The present paper reinvestigates the palaeobotanical and palynological assemblages of the Kuar Bet Beds, and discounts previous identiWcations of Onychiopsis, considering these specimens to represent a new species of the genus Coniopteris, Coniopteris kuarbetensis sp. nov. The plant macrofossil assemblage also contains ovulate scales of Araucarites Presl and rooting organs. Palynological preparations revealed a diverse assemblage that includes ?Sphagnumsporites, Cyathidites, Dictyophyllidites, Todisporites, Concavissimisporites, Klukisporites, Densoisporites, Callialasporites (two sp.), Alisporites spp., ?Podocarpidites, Araucariacites and Ginkgocycadophytus, all of which are long-ranging Mesozoic forms that occur in both Jurassic and Cretaceous sediments. Angiosperm pollen has not been observed, and the angiosperm grains reported by Mathur are here regarded as contaminants, introduced during the laboratory treatment of rock samples. Refuting the presence of Onychiopsis and of angiosperm pollen from the Kuar Bet Beds discounts an Early Cretaceous age, with the plant fossils and palynological assemblage being more consistent with a Middle Jurassic age, in general agreement with faunal data. However, the precise position within the Middle Jurassic remains uncertain with palaeobotanical and palynological results being most comparable with a late Middle Jurassic (Bathonian or Callovian) age while faunal evidence supports an early Middle Jurassic (Bajocian) age. © 2007 Elsevier Ltd. All rights reserved. Keywords: Stratigraphy; Jurassic; Cretaceous; Palaeobotany; Palynology; Coniopteris; Onychiopsis
1. Introduction and the stratigraphic problem The Kuar Bet Beds are exposed on Patcham Island in the Great Rann of Kachchh, Kachchh District, Gujarat (India) (Fig. 1), and are considered the oldest exposed Mesozoic strata in Kachchh (Wynne, 1872). The geological sequence exposed on Patcham Island comprises the littoral
*
Corresponding author. Fax: +91 0 522 2740098. E-mail address: [email protected] (B.N. Jana).
1367-9120/$ - see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2006.11.009
Kaladongar Formation and overlying sub-littoral Goradongar Formation, the sequence being conformable and undisturbed by tectonic activity (Biswas, 1977) (Fig. 2). The Kaladongar Formation is approximately 472 m thick in the type section in the northern scarp of the Kaladongar Hillock (below Babia Peak along a stream north of Narewari Wanth) of which the Kuar Bet Beds are the lower part of the formation comprising of alternating sandstones, conglomerates, red–green sandstones, and occasional shales, and an upper part that consists of yellow massive sandstones with calcareous bands. The Goradongar Formation
458
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 1. (a) Map of India showing position of Gujarat Province and with boxed area enlarged in (b). (b) Enlargement from (a) showing Katchchh and the Kuar Bet locality.
is approximately 152 m thick in its type section on the southern Xank of Modar Hill at the easternmost point of the Goradongar Range, and has a lower part that is predominantly shales and thin Xaggy fossiliferous calcareous bands, and an upper part that is dominated by sandstones with minor shales. The boundary between the two formations is marked by the Xaggy limestone/massive sandstone contact. Both of these formations are fossiliferous, and bio-
stratigraphical assessments have introduced controversy into the age of the Kuar Bet Beds; palaeozoological evidence supports a Middle Jurassic age whereas palaeobotanical and palynological investigations have lent support for an Early Cretaceous age (Fig. 2). According to Biswas (1977), sediments from the Kuar Bet region are the oldest Mesozoic sediments of Kachchh, which he considered as the Kuar Bet Member of the Kaladongar Formation. Wynne (1872) considered the oldest Mesozoic stratum in Kachchh to be of Bathonian age, based on faunal data. Later Waagen (1875) on the basis of ammonite biozonal assemblages, in comparison with the European ammonite occurrences, inferred a Bathonian age for the Patcham and Kuar Bet Beds. Raj Nath (1932, 1942) also concluded that the age range for the sequence on Patcham Island was from the Bathonian to early Callovian (Fig. 2). Jaitley and Singh (1983), on the basis of a study of ammonites collected from the Goradongar Formation, assigned a Bajocian age to the assemblage. Pandey and Dave (1993) after studying foraminiferal assemblages, also supported a Bajocian age for the Formation. On this evidence, combined with the order of stratigraphic superposition for the underlying Kaladongar Formation, Pandey and Dave (1993) conjectured that the Kaladongar Formation (including the Kuar Bet Member) was of Aalenian age (Fig. 2). However, Pandey and Dave (1993) noted that precise dating was not possible, due to the absence of diagnostic or biozonal fossils. Mathur (1972) studied plant megafossils from the Kuar Bet sediments exposed below Hill Point 144 in the Kuar Bet region (Fig. 1). In this part of India, individual hills have not been named, but are numbered on classiWed maps of the area which is a militarily sensitive region at present. As such we are not at liberty to reproduce maps elaborating the precise position of these localities. However, on the basis of the recovery of Onychiopsis sp. cf. Onychiopsis psilotoides (Stokes and Webb) Ward, an index fossil of an Early Cretaceous age, and Sphenopteris speciWca, Mathur (1972) disputed the age determined by the palaeozoological evidence and concluded that the age of Kuar Bet sediments could not be older than Early Cretaceous. He also recovered numerous pollen taxa from preparations made from the Kuar Bet Beds exposed at Hill Point 113 in the same region. These included the angiosperm pollen Scabramono-
Fig. 2. Chart showing biostratigraphic position of the Kuar Bet Beds.
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
colpites longicolpus Mathur, Psilatricolpites psilatus Habib, Tricolpites minutus Sah and Kar, Tricolpites levis Sah and Datta, T. spp., Retitricolporites Hammen and Wymstra, Umbelliferoipollenites ovatus Venkatachala and Kar, Retioctacolpite medicolpus Mathur, Proteacidites triangulus Mathur and Polyporina Potonie (Mathur, 1972). These angiosperm taxa led Mathur (1972) to conclude that the sediments were Cretaceous or younger, further discounting a Jurassic age. The controversy raised by Mathur’s (1972) palaeobotanical and palynological report regarding the age of the Kuar Bet Bed prompted one of us (BNJ) to reinvestigate the plant fossil evidence after making fresh collections from this locality. Samples were collected from Hill Points 113 and 144, the locations from which Mathur reportedly collected his samples. However, extensive collections of megafossils were made from the base of Hill Point 144, with the plant fossils occurring in grey and light-pink fragile shales that had undergone moderate amounts of weathering. Palynological samples were taken from both localities, but only the preparations made from Hill Point 144 were productive. The macro- and microXoral samples from Hill Point 144 are dealt with in the following pages. 2. Results 2.1. Palaeobotany The fossil plant assemblage is limited in diversity (Figs. 3 and 4), with three kinds of plant fossil preserved, the vast majority of specimens belonging to a single taxon. 2.1.1. Coniopteris Brongniart, 1840 Description. A single species of Coniopteris dominates the macrofossil assemblage, accounting for more than 95% of fossils encountered, and represented by isolated fronds and pinnae (Fig. 3). Fronds are linear/lanceolate shaped and range from 12 to 25 mm long and 8 to 14 mm wide (Fig. 3A and B). Individual fronds are bipinnate and have a pinna rachis measuring 0.5–1 mm wide. Some specimens show the pinna rachis to have an irregular ‘blotchy’ surface (Fig. 3A), while others have prominent longitudinally oriented striations through the pinna rachis midrib and a pinnule midrib that represents the position of the vascular tissue. On the pinna rachis the majority of pinnules are alternately arranged, arising at intervals of between 1.75 mm and 2 mm and with an angle of departure typically at 40°– 45°. Basal pinnules are 1–1.5 mm long and 0.5–1 mm wide, rhomboidal or wedge-shaped, and in most cases trilobed (Fig. 3A and B). However, some basal pinnules have 4–5 lobes (Fig. 3B), and in these the lobes are mostly subacute or obtuse (Fig. 3E). Lateral pinnule lobes both rounded or broadly obtuse (Fig. 3E). Pinnule margins are basiscopic as well as acroscopic are decurrent (Fig. 3B, D, and E), and sometimes have acroscopic margins that are constricted (Fig. 3B).
459
Considerable variation is noted in the pinnules of this species, including specimens that are comparatively long and thin, taper strongly, and have highly reduced distal morphology (e.g. Fig. 3D). These are interpreted as representing apically positioned pinnules on the frond or the apex of the frond itself. 3. Systematic palaeobotany Order: Filicales Family: Dicksoniaceae Genus: Coniopteris Species: Coniopteris kuarbetensis sp. nov. (Fig. 3). Holotype: B.S.I.P. Specimen No. 93/6695B. Locality: Kuar Bet, Kachchh District, Gujarat, India. Horizon and age: Kaladongar Formation, Middle Jurassic Derivation of speciWc epithet: the species is named after the region in which the fossil assemblage occurs. Diagnosis. Fronds linear/lanceolate, 12–25 mm long, 8– 14 mm wide, bipinnate, pinna rachis measuring 0.5–1 mm, with some specimens showing longitudinal striations throughout the length. Majority of pinnules alternate, arising at 1.75–2 mm intervals and with angle of departure typically from 40°–45°. Basal pinnules measuring 1–1.5 mm long, 0.5–1 mm wide, are rhomboidal or wedge-shaped, mostly trilobed. Basal pinnules with 4–5 lobes, with the margin of each lobe further notched at unequal distances, apices mostly sub acute or obtuse. Lateral lobes rounded or broadly obtuse. Basiscopic and acroscopic pinnule margins are decurrent, acroscopic margins sometimes constricted. Only sterile material was seen. Comparison with other species of Coniopteris. The specimens we describe diVer from the genus Onychiopsis that has bipinnate fronds with a thick main rachis, linear pinnules organised in an alternate pattern, and with irregularly wedgeshaped sterile pinnules with prominent lobes with acute apices and entire or dentate margins. In particular, the specimens from Kuar Bet lack the prominent dichotomous venation characteristic of Onychiopsis, excluding it from the genus. The Kuar Bet foliage is similar to species of the fern genus Coniopteris described by Harris from the Yorkshire Jurassic Flora, and conforms with the features of this genus, in having linear/lanceolate shaped fronds with alternate pinnules with an angle of departure between 40° and 45°, and with rhomboidal-wedge-shaped and lobed basal pinnules, and sub acute or obtuse apices (e.g. Harris, 1961; Deng and Chen, 2001). However, it is distinct from those species previously identiWed; hence we erect a new species, C. kuarbetensis sp. nov. to accommodate it. C. kuarbetensis in general appearance resembles the sterile fronds of Coniopteris hymenophylloides (Brongniart) Harris, described by Harris (1961, Fig. 53). However, the sterile pinnules of C. hymenophylloides diVer from C. kuarbetensis in having pinnules with many lobes. The pattern of branching in the pinnate fern leaves of Coniopteris simplex Harris (Harris, 1961, Fig. 53H–K) also resembles C. kuarbetensis sp. nov.
460
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 3. Coniopteris kuarbetensis sp. nov. from the Kuar Bet Beds, Kuar Bet Section, Hill Point 144 (Kachchh, Gujarat, India). (A) Frond with wide rachis showing ‘blotchy’ surface and alternate pinnae [BSIP 26/6695B]. (B) Frond with prominent central ridges in the main rachis and pinnae showing position of midvein (arrow, M), and with pinnules generally decurrent (arrow, D) with acroscopic and basioscopic margins, rarely with constricted margins [Holotype, BSIP 93/665B]. (C) Enlargement from (A) showing pinnule morphology. (D) Immature frond with highly reduced apical lobes and basal pinnae in diVerent stages of development, and constricted acroscopic margin (arrow, C) [BSIP 33/6695B]. (E) Enlarged pinnae showing nature of pinnule margin with obtuse to rounded pinnule lobes (arrow, R) [BSIP 47/6695B]. All scale bars, 2 mm.
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
However, C. simplex diVers markedly, having much thinner pinnules, and also has more variation in sterile frond morphology. In both of these species from Yorkshire the sterile and fertile pinnules are known, but an absence of fertile pinnules from Kuar Bet precludes comparison with these species. Other species of Coniopteris resemble the present species, including Coniopteris cf. hymenophylloides recorded by Bose and Banerji (1984, plate 3, Figs. 1–4, Text-Figs. A–F) from the Bhuj Formation of Kachchh, and Coniopteris onichoides Vassil et Kara-Mur recorded by Deng (1995) from the Cretaceous of Inner Mongolia, China. The specimens illustrated by Bose and Banerji (1984) resemble C. kuarbetensis in their outward appearance, but diVer by having a more lobes and forked venation (Bose and Banerji, 1984). C. onichoides from China diVers in having a much broader branched frond with linear shaped pinnules. Although distinct from the species we describe here, the species from China is interesting in that its speciWc name denotes a similarity between the leaves of Coniopteris and Onychiopsis. 3.1. Genus - Araucarites Presl, 1838 (Fig. 4A) Description. Single detached cone scale with centrally located seed, measuring 7£4.4mm, shape obcuneate, base truncate and tip rounded. Seed obovate, measuring 0.6£4mm.
461
4. Palynological results From Hill Point 144 spores and pollen are rare but 19 taxa belonging to 17 genera have been identiWed. Of these occurrences 13 genera and 16 species are Mesozoic forms and these are illustrated in Fig. 5A–Q. The remaining taxa represent reworked Palaeozoic species. The Jurassic taxa present are ?Sphagnumsporites sp. (Fig. 4A), Cyathidites australis (Fig. 5B and C), Cyathidites concavus (Fig. 5D), Dictyophyllidites harrisii (Fig. 5E), Todisporites major (Fig. 5F), Concavissimisporites sp. cf. Concavissimisporites variverrucatus. (Fig. 5G), Densoisporites sp. (Fig. 5H), Klukisporites sp. (Fig. 5I), Callialasporites dampieri (Fig. 5J and K), Callialasporites sp. (Fig. 5L), Alisporites sp. A (Fig. 5M), Alisporites sp. B (Fig. 5N), ?Podocarpidites sp. (Fig. 5O), Araucariacites australis (Fig. 5P) and Ginkgocycadophytes sp. (Fig. 5Q). Araucariacites is dominant, with other taxa only being rarely encountered in the assemblage. In the palyno-assemblage four reworked Permian genera are present, namely: Plicatipollenites sp., Parasaccites sp., Virkkipollenites sp. (not illustrated) and Striatites (Fig. 5R). These palynomorph genera have been previously recorded in Jurassic assemblages from the Kachchh mainland (Venkatachala, 1970; Maheshwari and Jana, 2004). In our preparations neither angiosperm pollen nor nannofossils have been observed.
3.2. Roots (Fig. 4B) 5. Discussion Description. Roots well-preserved, main root measuring 18 mm long, and 1.75 mm broad, with distinct central vascular strand 0.5 mm in diameter; lateral roots 0.5 mm thick, arising from central vascular bundle at intervals of 2 mm, at 90°–130° from the main root, tips of these are mostly with downward direction.
Species of Coniopteris are known from Jurassic and Cretaceous sediments across the world including Europe (e.g. Harris, 1961), India (Bose and Banerji, 1984; Patra, 1990) and China (e.g. Deng, 1995). This genus is long ranging and is not stratigraphically informative. As C. kuarbetensis sp.
Fig. 4. Other plant organs from the Kuar Bet Beds, Kuar Bet Section, Hill Point 144. (A) Cone scale with attached ovule of Araucarites sp. BSIP 14/6695B. (B) Rooting organ. BSIP 28/6695B. Scale bars, 2 mm.
462
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 5. Palynomorphs from Kuar Bet Beds, Kuar Bet section, Hill Point 144. A. ?Sphagnumsporites sp. [Slide BSIP 13264, England Finder co-ordinate N3]. (B and C) Cyathidites australis [B. BSIP 13265, K-7, C. BSIP 13265, O-40]. (D) Cyathidites concavus [BSIP13266, O-7]. (E) Dictyophyllidites harrisii [BSIP 13265, N-14]. (F) Todisporites major [BSIP 13267, T-11]. (G) Concavissimisporites sp. cf. C. variverrucatus [BSIP 13268, N-27]. (H) Densoisporites sp [BSIP 13265, L-14]. I. Klukisporites sp. [BSIP 13264, D-19]. (J and K) Callialasporites dampieri [J. BSIP 13267, J-10, K. BSIP 13269, V-29]. (L) Callialasporites sp. [BSIP 13267, M-21]. M. Alisporites sp A. [BSIP 13269, N-12]. (N) Alisporites sp B. [BSIP 13269, N-22]. (O) ?Podocarpidites sp. [BSIP 13270, F-12]. (P) Araucariacites australis [BSIP 13269, M-24. (Q) Ginkgocycadophytus sp. [BSIP 13267, V-23]. (R) Reworked Permian pollen grain Striatites sp. [BSIP 13271, F-34]. (A–Q) Images at same magniWcation and with scale bar shown in (A), 20 m. (R) Scale bar, 20 m.
nov. has only been identiWed from a single locality, its stratigraphical signiWcance is presently unknown. The occurrence of Araucarites sp. is of no stratigraphic importance as this genus is also long ranging, and similarly occurs in both Jurassic and Cretaceous strata. Likewise, rooting organs are common in many Palaeozoic and Mesozoic pal-
aeobotanical assemblages and are of no stratigraphic signiWcance. The controversy regarding the age of the Kuar Bet Beds arose for the erroneous identiWcation of the genus Coniopteris by Mathur (1972) as Onychiopsis sp. cf. O. psilotoides, in combination with the identiWcation of presumed
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Cretaceous–Cenozoic palynomorphs (see below). The genus Onychiopsis was considered as a stratigraphical index taxon restricted to the Lower Cretaceous (e.g. Bose and Sukh-Dev, 1961; Mathur, 1972), but as this is not present in the Kuar Bet Beds this no longer supports a Cretaceous age. Palynomorphs are rare in the preparations made from the Kuar Bet Beds during the course of this investigation. All of the taxa present are long-ranging and are known from both Jurassic and Cretaceous strata. The palynological assemblage as a whole is indicative of a late Middle Jurassic (Bathonian–Callovian) age (e.g. Burger, 1995). In this account we note that the palynomorphs we have recovered are dark in colour and are very diVerent from the light coloured pollen illustrated by Mathur (1972), leading us to conclude that the palynomorphs he illustrated were laboratory contamination by younger (?Recent) pollen. Considering the uninterrupted stratigraphical sequence on Patcham Island (e.g. Biswas, 1977) we do not consider it feasible to have Cretaceous–Cenozoic rocks below the Goradongar Formation that is reliably dated, using ammonites (Jaitley and Singh, 1983) and foraminifera (Pandey and Dave, 1993), as Bajocian. The present evidence derived from plant megafossils and palynology as a whole is indicative of Late Middle Jurassic (Bathonian or Callovian) age for the Kuar Bet Beds, as was proposed by earlier workers including Waagen (1875), Raj Nath (1932, 1942), Wynne (1872), and Biswas (1977). Our conclusion is therefore that the Kuar Bet Beds are Middle Jurassic in age, but we consider them to be late Middle Jurassic rather than Bajocian as advocated from the faunal data (Fig. 2). Either way, a Middle Jurassic age for this formation ends the long standing controversy regarding the age of Kuar Bet Beds. 6. Conclusions Reinvestigation of the palaeobotanical and palynological assemblages from the Kuar Bet Beds in Patcham Island (Kachchh) document taxa consistent with a late Middle Jurassic age, and did not Wnd any Cretaceous–Cenozoic forms. Reworked Permian pollen is present, but, angiosperm pollen is absent. This palaeobotanical study discounts previous interpretations of an Early Cretaceous age for the Kuar Bet Beds, and agrees with faunal data that suggest a Middle Jurassic age. However, the precise position within the Middle Jurassic remains uncertain, as palynological assemblages are consistent with a Late Middle Jurassic (Bathonian–Callovian) age, while ammonite and foraminifera occurrences are consistent with an early Middle Jurassic (Bajocian) age. Acknowledgements The authors acknowledge the Wnancial support of the Bilateral Exchange Program of the Indian National
463
Science Academy (INSA) and Royal Society (Incoming Short Visit 2005/R3), and the Director, Birbal Sahni Institute of Palaeobotany for travel support (to B.N.J.). We thank Anthony Hallam (University of Birmingham) for discussion, Aruna Mistry (University of Birmingham) and Suresh C. Pillai (Birbal Sahni Institute of Palaeobotany) for technical assistance. Professors W. G. Chaloner and D. J. Batten are thanked for positive and constructive reviews on the manuscript. References Biswas, S.K., 1977. The Mesozoic rocks – stratigraphy of Kutch. Quarterly Journal of Geological Mining and Metallurgical Society of India 49, 1–51. Bose, M.N., Banerji, J., 1984. The fossil Xoras of Kachchh. I. Mesozoic megafossils. Palaeobotanist 33, 1–189. Bose, M.N., Sukh-Dev, 1961. Studies on the fossil Xora of the Jabalpur Series from the South Rewa Gondwana Basin – 2. Onychiopsisis paradoxus n. sp. Palaeobotanist 8, 57–64. Burger, D. 1995. Timescales 8. Jurassic. Australian Phanerozoic Time Scales Biostratigraphic Charts and Explanatory Notes. Second Series. AGSO Record 37, pp. 1–30. Deng, S., 1995. Early Cretaceous Xora of Huolinhe Basin, Inner Mongolia, northeast China. Geological Publishing House, Beijing. 1–125, 48 pls (in Chinese with English summary). Deng, S.H., Chen, F., 2001. The Early Cretaceous Filicopsida from northeast China. Geological Publishing House, Beijing. 1–249, 124 pls. Harris, T.M., 1961. The Yorkshire Jurassic Flora. I Thallophyta–Pteridophyta. British Museum (Natural History), London, pp. 1–212. Jaitley, A.K., Singh, C.S.P., 1983. Discovery of Late Bajocian Leptosphinctes Buckman (Jurassic Ammonitina) from Kachchh, Western India. Neus Jahrbuch für Geologie und Paläontologie 2, 91–96. Maheshwari, H.K., Jana, B.N. 2004. Spores and pollen of the Ptilophyllum Flora of Kutch Basin, India. In: Srivastava, P.C. (Ed.). Vistas in Indian Palaeobotany and Plant Morphology: Evolutionary and Environmental Perspectives. Professor D.D. Pant Memorial Volume. U.P. OVset, Lucknow, India, pp. 207–219. Mathur, Y.K., 1972. The plant fossils from the Kuar Bet, Patcham Island, Kutch. Current Science 41, 488–489. Nath, Raj, 1932. A contribution to the stratigraphy of Cutch. Quarterly Journal of the Geological Mining and Metallurgical Society of India 4, 162– 174. Nath, Raj, 1942. Jurassic rocks of Cutch – their bearing on the stratigraphy of some problem of Indian Geology. Proceedings of the Indian Science Congress 29, 93–106. Pandey, J., Dave, A., 1993. Studies in Mesozoic Foraminifera and chronostratigraphy of Western Kutch Gujarat. Palaeontographica Indica 1, 1–219. Patra, B.P., 1990. On some species of Coniopteris occurring in the Athgarh Sandstone, Cuttack district, Orissa. Proceedings of the 77th Indian Science Congress, Cochin 3, pp. 30–31. Venkatachala, B.S. 1970. Palynology of the Mesozoic sediments of Kutch, W. India. 7. Reworked Permian pollen from the Upper Jurassic sediments – a discussion. Palaeobotanist 18, pp. 45-49. Waagen, W., 1875. Abstract of results of the results of examination of the ammonite fauna of Kuch with remarks on their distribution among the beds and probable age. Records of the Geological Survey of India 4, 89–101. Wynne, A.B., 1872. Memoir on the geology of Cutch to accompany a map compiled by A.B. Wynne and F. Fedden, during the seasons 1867–68, 1868–69. Memoirs of the Geological Survey of India 9, pp. 1–289.
Resolving the age of the Mesozoic Kuar Bet Beds (Kachchh, Gujarat, India): A reinvestigation of palaeobotanical and palynological assemblages Brajendra Nath Jana a,¤, Jason Hilton b a
b
Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226 007, India School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK Received 16 October 2006; accepted 30 November 2006
Abstract Within the Mesozoic sedimentary sequences of India the age of the Kuar Bet Beds in Kachchh (Gujarat Province) has been hotly contested, with faunal evidence suggesting a Bathonian (Middle Jurassic) age, based on ammonite and foraminiferal occurrences, and palaeobotanical evidence suggesting an Early Cretaceous age, based on the presence of the index fossil Onychiopsis sp. cf. psilotoides (Stokes and Webb) Ward. Previously reported palynological evidence has documented numerous angiosperm pollen taxa, lending further support to an Early Cretaceous age. The present paper reinvestigates the palaeobotanical and palynological assemblages of the Kuar Bet Beds, and discounts previous identiWcations of Onychiopsis, considering these specimens to represent a new species of the genus Coniopteris, Coniopteris kuarbetensis sp. nov. The plant macrofossil assemblage also contains ovulate scales of Araucarites Presl and rooting organs. Palynological preparations revealed a diverse assemblage that includes ?Sphagnumsporites, Cyathidites, Dictyophyllidites, Todisporites, Concavissimisporites, Klukisporites, Densoisporites, Callialasporites (two sp.), Alisporites spp., ?Podocarpidites, Araucariacites and Ginkgocycadophytus, all of which are long-ranging Mesozoic forms that occur in both Jurassic and Cretaceous sediments. Angiosperm pollen has not been observed, and the angiosperm grains reported by Mathur are here regarded as contaminants, introduced during the laboratory treatment of rock samples. Refuting the presence of Onychiopsis and of angiosperm pollen from the Kuar Bet Beds discounts an Early Cretaceous age, with the plant fossils and palynological assemblage being more consistent with a Middle Jurassic age, in general agreement with faunal data. However, the precise position within the Middle Jurassic remains uncertain with palaeobotanical and palynological results being most comparable with a late Middle Jurassic (Bathonian or Callovian) age while faunal evidence supports an early Middle Jurassic (Bajocian) age. © 2007 Elsevier Ltd. All rights reserved. Keywords: Stratigraphy; Jurassic; Cretaceous; Palaeobotany; Palynology; Coniopteris; Onychiopsis
1. Introduction and the stratigraphic problem The Kuar Bet Beds are exposed on Patcham Island in the Great Rann of Kachchh, Kachchh District, Gujarat (India) (Fig. 1), and are considered the oldest exposed Mesozoic strata in Kachchh (Wynne, 1872). The geological sequence exposed on Patcham Island comprises the littoral
*
Corresponding author. Fax: +91 0 522 2740098. E-mail address: [email protected] (B.N. Jana).
1367-9120/$ - see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2006.11.009
Kaladongar Formation and overlying sub-littoral Goradongar Formation, the sequence being conformable and undisturbed by tectonic activity (Biswas, 1977) (Fig. 2). The Kaladongar Formation is approximately 472 m thick in the type section in the northern scarp of the Kaladongar Hillock (below Babia Peak along a stream north of Narewari Wanth) of which the Kuar Bet Beds are the lower part of the formation comprising of alternating sandstones, conglomerates, red–green sandstones, and occasional shales, and an upper part that consists of yellow massive sandstones with calcareous bands. The Goradongar Formation
458
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 1. (a) Map of India showing position of Gujarat Province and with boxed area enlarged in (b). (b) Enlargement from (a) showing Katchchh and the Kuar Bet locality.
is approximately 152 m thick in its type section on the southern Xank of Modar Hill at the easternmost point of the Goradongar Range, and has a lower part that is predominantly shales and thin Xaggy fossiliferous calcareous bands, and an upper part that is dominated by sandstones with minor shales. The boundary between the two formations is marked by the Xaggy limestone/massive sandstone contact. Both of these formations are fossiliferous, and bio-
stratigraphical assessments have introduced controversy into the age of the Kuar Bet Beds; palaeozoological evidence supports a Middle Jurassic age whereas palaeobotanical and palynological investigations have lent support for an Early Cretaceous age (Fig. 2). According to Biswas (1977), sediments from the Kuar Bet region are the oldest Mesozoic sediments of Kachchh, which he considered as the Kuar Bet Member of the Kaladongar Formation. Wynne (1872) considered the oldest Mesozoic stratum in Kachchh to be of Bathonian age, based on faunal data. Later Waagen (1875) on the basis of ammonite biozonal assemblages, in comparison with the European ammonite occurrences, inferred a Bathonian age for the Patcham and Kuar Bet Beds. Raj Nath (1932, 1942) also concluded that the age range for the sequence on Patcham Island was from the Bathonian to early Callovian (Fig. 2). Jaitley and Singh (1983), on the basis of a study of ammonites collected from the Goradongar Formation, assigned a Bajocian age to the assemblage. Pandey and Dave (1993) after studying foraminiferal assemblages, also supported a Bajocian age for the Formation. On this evidence, combined with the order of stratigraphic superposition for the underlying Kaladongar Formation, Pandey and Dave (1993) conjectured that the Kaladongar Formation (including the Kuar Bet Member) was of Aalenian age (Fig. 2). However, Pandey and Dave (1993) noted that precise dating was not possible, due to the absence of diagnostic or biozonal fossils. Mathur (1972) studied plant megafossils from the Kuar Bet sediments exposed below Hill Point 144 in the Kuar Bet region (Fig. 1). In this part of India, individual hills have not been named, but are numbered on classiWed maps of the area which is a militarily sensitive region at present. As such we are not at liberty to reproduce maps elaborating the precise position of these localities. However, on the basis of the recovery of Onychiopsis sp. cf. Onychiopsis psilotoides (Stokes and Webb) Ward, an index fossil of an Early Cretaceous age, and Sphenopteris speciWca, Mathur (1972) disputed the age determined by the palaeozoological evidence and concluded that the age of Kuar Bet sediments could not be older than Early Cretaceous. He also recovered numerous pollen taxa from preparations made from the Kuar Bet Beds exposed at Hill Point 113 in the same region. These included the angiosperm pollen Scabramono-
Fig. 2. Chart showing biostratigraphic position of the Kuar Bet Beds.
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
colpites longicolpus Mathur, Psilatricolpites psilatus Habib, Tricolpites minutus Sah and Kar, Tricolpites levis Sah and Datta, T. spp., Retitricolporites Hammen and Wymstra, Umbelliferoipollenites ovatus Venkatachala and Kar, Retioctacolpite medicolpus Mathur, Proteacidites triangulus Mathur and Polyporina Potonie (Mathur, 1972). These angiosperm taxa led Mathur (1972) to conclude that the sediments were Cretaceous or younger, further discounting a Jurassic age. The controversy raised by Mathur’s (1972) palaeobotanical and palynological report regarding the age of the Kuar Bet Bed prompted one of us (BNJ) to reinvestigate the plant fossil evidence after making fresh collections from this locality. Samples were collected from Hill Points 113 and 144, the locations from which Mathur reportedly collected his samples. However, extensive collections of megafossils were made from the base of Hill Point 144, with the plant fossils occurring in grey and light-pink fragile shales that had undergone moderate amounts of weathering. Palynological samples were taken from both localities, but only the preparations made from Hill Point 144 were productive. The macro- and microXoral samples from Hill Point 144 are dealt with in the following pages. 2. Results 2.1. Palaeobotany The fossil plant assemblage is limited in diversity (Figs. 3 and 4), with three kinds of plant fossil preserved, the vast majority of specimens belonging to a single taxon. 2.1.1. Coniopteris Brongniart, 1840 Description. A single species of Coniopteris dominates the macrofossil assemblage, accounting for more than 95% of fossils encountered, and represented by isolated fronds and pinnae (Fig. 3). Fronds are linear/lanceolate shaped and range from 12 to 25 mm long and 8 to 14 mm wide (Fig. 3A and B). Individual fronds are bipinnate and have a pinna rachis measuring 0.5–1 mm wide. Some specimens show the pinna rachis to have an irregular ‘blotchy’ surface (Fig. 3A), while others have prominent longitudinally oriented striations through the pinna rachis midrib and a pinnule midrib that represents the position of the vascular tissue. On the pinna rachis the majority of pinnules are alternately arranged, arising at intervals of between 1.75 mm and 2 mm and with an angle of departure typically at 40°– 45°. Basal pinnules are 1–1.5 mm long and 0.5–1 mm wide, rhomboidal or wedge-shaped, and in most cases trilobed (Fig. 3A and B). However, some basal pinnules have 4–5 lobes (Fig. 3B), and in these the lobes are mostly subacute or obtuse (Fig. 3E). Lateral pinnule lobes both rounded or broadly obtuse (Fig. 3E). Pinnule margins are basiscopic as well as acroscopic are decurrent (Fig. 3B, D, and E), and sometimes have acroscopic margins that are constricted (Fig. 3B).
459
Considerable variation is noted in the pinnules of this species, including specimens that are comparatively long and thin, taper strongly, and have highly reduced distal morphology (e.g. Fig. 3D). These are interpreted as representing apically positioned pinnules on the frond or the apex of the frond itself. 3. Systematic palaeobotany Order: Filicales Family: Dicksoniaceae Genus: Coniopteris Species: Coniopteris kuarbetensis sp. nov. (Fig. 3). Holotype: B.S.I.P. Specimen No. 93/6695B. Locality: Kuar Bet, Kachchh District, Gujarat, India. Horizon and age: Kaladongar Formation, Middle Jurassic Derivation of speciWc epithet: the species is named after the region in which the fossil assemblage occurs. Diagnosis. Fronds linear/lanceolate, 12–25 mm long, 8– 14 mm wide, bipinnate, pinna rachis measuring 0.5–1 mm, with some specimens showing longitudinal striations throughout the length. Majority of pinnules alternate, arising at 1.75–2 mm intervals and with angle of departure typically from 40°–45°. Basal pinnules measuring 1–1.5 mm long, 0.5–1 mm wide, are rhomboidal or wedge-shaped, mostly trilobed. Basal pinnules with 4–5 lobes, with the margin of each lobe further notched at unequal distances, apices mostly sub acute or obtuse. Lateral lobes rounded or broadly obtuse. Basiscopic and acroscopic pinnule margins are decurrent, acroscopic margins sometimes constricted. Only sterile material was seen. Comparison with other species of Coniopteris. The specimens we describe diVer from the genus Onychiopsis that has bipinnate fronds with a thick main rachis, linear pinnules organised in an alternate pattern, and with irregularly wedgeshaped sterile pinnules with prominent lobes with acute apices and entire or dentate margins. In particular, the specimens from Kuar Bet lack the prominent dichotomous venation characteristic of Onychiopsis, excluding it from the genus. The Kuar Bet foliage is similar to species of the fern genus Coniopteris described by Harris from the Yorkshire Jurassic Flora, and conforms with the features of this genus, in having linear/lanceolate shaped fronds with alternate pinnules with an angle of departure between 40° and 45°, and with rhomboidal-wedge-shaped and lobed basal pinnules, and sub acute or obtuse apices (e.g. Harris, 1961; Deng and Chen, 2001). However, it is distinct from those species previously identiWed; hence we erect a new species, C. kuarbetensis sp. nov. to accommodate it. C. kuarbetensis in general appearance resembles the sterile fronds of Coniopteris hymenophylloides (Brongniart) Harris, described by Harris (1961, Fig. 53). However, the sterile pinnules of C. hymenophylloides diVer from C. kuarbetensis in having pinnules with many lobes. The pattern of branching in the pinnate fern leaves of Coniopteris simplex Harris (Harris, 1961, Fig. 53H–K) also resembles C. kuarbetensis sp. nov.
460
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 3. Coniopteris kuarbetensis sp. nov. from the Kuar Bet Beds, Kuar Bet Section, Hill Point 144 (Kachchh, Gujarat, India). (A) Frond with wide rachis showing ‘blotchy’ surface and alternate pinnae [BSIP 26/6695B]. (B) Frond with prominent central ridges in the main rachis and pinnae showing position of midvein (arrow, M), and with pinnules generally decurrent (arrow, D) with acroscopic and basioscopic margins, rarely with constricted margins [Holotype, BSIP 93/665B]. (C) Enlargement from (A) showing pinnule morphology. (D) Immature frond with highly reduced apical lobes and basal pinnae in diVerent stages of development, and constricted acroscopic margin (arrow, C) [BSIP 33/6695B]. (E) Enlarged pinnae showing nature of pinnule margin with obtuse to rounded pinnule lobes (arrow, R) [BSIP 47/6695B]. All scale bars, 2 mm.
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
However, C. simplex diVers markedly, having much thinner pinnules, and also has more variation in sterile frond morphology. In both of these species from Yorkshire the sterile and fertile pinnules are known, but an absence of fertile pinnules from Kuar Bet precludes comparison with these species. Other species of Coniopteris resemble the present species, including Coniopteris cf. hymenophylloides recorded by Bose and Banerji (1984, plate 3, Figs. 1–4, Text-Figs. A–F) from the Bhuj Formation of Kachchh, and Coniopteris onichoides Vassil et Kara-Mur recorded by Deng (1995) from the Cretaceous of Inner Mongolia, China. The specimens illustrated by Bose and Banerji (1984) resemble C. kuarbetensis in their outward appearance, but diVer by having a more lobes and forked venation (Bose and Banerji, 1984). C. onichoides from China diVers in having a much broader branched frond with linear shaped pinnules. Although distinct from the species we describe here, the species from China is interesting in that its speciWc name denotes a similarity between the leaves of Coniopteris and Onychiopsis. 3.1. Genus - Araucarites Presl, 1838 (Fig. 4A) Description. Single detached cone scale with centrally located seed, measuring 7£4.4mm, shape obcuneate, base truncate and tip rounded. Seed obovate, measuring 0.6£4mm.
461
4. Palynological results From Hill Point 144 spores and pollen are rare but 19 taxa belonging to 17 genera have been identiWed. Of these occurrences 13 genera and 16 species are Mesozoic forms and these are illustrated in Fig. 5A–Q. The remaining taxa represent reworked Palaeozoic species. The Jurassic taxa present are ?Sphagnumsporites sp. (Fig. 4A), Cyathidites australis (Fig. 5B and C), Cyathidites concavus (Fig. 5D), Dictyophyllidites harrisii (Fig. 5E), Todisporites major (Fig. 5F), Concavissimisporites sp. cf. Concavissimisporites variverrucatus. (Fig. 5G), Densoisporites sp. (Fig. 5H), Klukisporites sp. (Fig. 5I), Callialasporites dampieri (Fig. 5J and K), Callialasporites sp. (Fig. 5L), Alisporites sp. A (Fig. 5M), Alisporites sp. B (Fig. 5N), ?Podocarpidites sp. (Fig. 5O), Araucariacites australis (Fig. 5P) and Ginkgocycadophytes sp. (Fig. 5Q). Araucariacites is dominant, with other taxa only being rarely encountered in the assemblage. In the palyno-assemblage four reworked Permian genera are present, namely: Plicatipollenites sp., Parasaccites sp., Virkkipollenites sp. (not illustrated) and Striatites (Fig. 5R). These palynomorph genera have been previously recorded in Jurassic assemblages from the Kachchh mainland (Venkatachala, 1970; Maheshwari and Jana, 2004). In our preparations neither angiosperm pollen nor nannofossils have been observed.
3.2. Roots (Fig. 4B) 5. Discussion Description. Roots well-preserved, main root measuring 18 mm long, and 1.75 mm broad, with distinct central vascular strand 0.5 mm in diameter; lateral roots 0.5 mm thick, arising from central vascular bundle at intervals of 2 mm, at 90°–130° from the main root, tips of these are mostly with downward direction.
Species of Coniopteris are known from Jurassic and Cretaceous sediments across the world including Europe (e.g. Harris, 1961), India (Bose and Banerji, 1984; Patra, 1990) and China (e.g. Deng, 1995). This genus is long ranging and is not stratigraphically informative. As C. kuarbetensis sp.
Fig. 4. Other plant organs from the Kuar Bet Beds, Kuar Bet Section, Hill Point 144. (A) Cone scale with attached ovule of Araucarites sp. BSIP 14/6695B. (B) Rooting organ. BSIP 28/6695B. Scale bars, 2 mm.
462
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Fig. 5. Palynomorphs from Kuar Bet Beds, Kuar Bet section, Hill Point 144. A. ?Sphagnumsporites sp. [Slide BSIP 13264, England Finder co-ordinate N3]. (B and C) Cyathidites australis [B. BSIP 13265, K-7, C. BSIP 13265, O-40]. (D) Cyathidites concavus [BSIP13266, O-7]. (E) Dictyophyllidites harrisii [BSIP 13265, N-14]. (F) Todisporites major [BSIP 13267, T-11]. (G) Concavissimisporites sp. cf. C. variverrucatus [BSIP 13268, N-27]. (H) Densoisporites sp [BSIP 13265, L-14]. I. Klukisporites sp. [BSIP 13264, D-19]. (J and K) Callialasporites dampieri [J. BSIP 13267, J-10, K. BSIP 13269, V-29]. (L) Callialasporites sp. [BSIP 13267, M-21]. M. Alisporites sp A. [BSIP 13269, N-12]. (N) Alisporites sp B. [BSIP 13269, N-22]. (O) ?Podocarpidites sp. [BSIP 13270, F-12]. (P) Araucariacites australis [BSIP 13269, M-24. (Q) Ginkgocycadophytus sp. [BSIP 13267, V-23]. (R) Reworked Permian pollen grain Striatites sp. [BSIP 13271, F-34]. (A–Q) Images at same magniWcation and with scale bar shown in (A), 20 m. (R) Scale bar, 20 m.
nov. has only been identiWed from a single locality, its stratigraphical signiWcance is presently unknown. The occurrence of Araucarites sp. is of no stratigraphic importance as this genus is also long ranging, and similarly occurs in both Jurassic and Cretaceous strata. Likewise, rooting organs are common in many Palaeozoic and Mesozoic pal-
aeobotanical assemblages and are of no stratigraphic signiWcance. The controversy regarding the age of the Kuar Bet Beds arose for the erroneous identiWcation of the genus Coniopteris by Mathur (1972) as Onychiopsis sp. cf. O. psilotoides, in combination with the identiWcation of presumed
B.N. Jana, J. Hilton / Journal of Asian Earth Sciences 30 (2007) 457–463
Cretaceous–Cenozoic palynomorphs (see below). The genus Onychiopsis was considered as a stratigraphical index taxon restricted to the Lower Cretaceous (e.g. Bose and Sukh-Dev, 1961; Mathur, 1972), but as this is not present in the Kuar Bet Beds this no longer supports a Cretaceous age. Palynomorphs are rare in the preparations made from the Kuar Bet Beds during the course of this investigation. All of the taxa present are long-ranging and are known from both Jurassic and Cretaceous strata. The palynological assemblage as a whole is indicative of a late Middle Jurassic (Bathonian–Callovian) age (e.g. Burger, 1995). In this account we note that the palynomorphs we have recovered are dark in colour and are very diVerent from the light coloured pollen illustrated by Mathur (1972), leading us to conclude that the palynomorphs he illustrated were laboratory contamination by younger (?Recent) pollen. Considering the uninterrupted stratigraphical sequence on Patcham Island (e.g. Biswas, 1977) we do not consider it feasible to have Cretaceous–Cenozoic rocks below the Goradongar Formation that is reliably dated, using ammonites (Jaitley and Singh, 1983) and foraminifera (Pandey and Dave, 1993), as Bajocian. The present evidence derived from plant megafossils and palynology as a whole is indicative of Late Middle Jurassic (Bathonian or Callovian) age for the Kuar Bet Beds, as was proposed by earlier workers including Waagen (1875), Raj Nath (1932, 1942), Wynne (1872), and Biswas (1977). Our conclusion is therefore that the Kuar Bet Beds are Middle Jurassic in age, but we consider them to be late Middle Jurassic rather than Bajocian as advocated from the faunal data (Fig. 2). Either way, a Middle Jurassic age for this formation ends the long standing controversy regarding the age of Kuar Bet Beds. 6. Conclusions Reinvestigation of the palaeobotanical and palynological assemblages from the Kuar Bet Beds in Patcham Island (Kachchh) document taxa consistent with a late Middle Jurassic age, and did not Wnd any Cretaceous–Cenozoic forms. Reworked Permian pollen is present, but, angiosperm pollen is absent. This palaeobotanical study discounts previous interpretations of an Early Cretaceous age for the Kuar Bet Beds, and agrees with faunal data that suggest a Middle Jurassic age. However, the precise position within the Middle Jurassic remains uncertain, as palynological assemblages are consistent with a Late Middle Jurassic (Bathonian–Callovian) age, while ammonite and foraminifera occurrences are consistent with an early Middle Jurassic (Bajocian) age. Acknowledgements The authors acknowledge the Wnancial support of the Bilateral Exchange Program of the Indian National
463
Science Academy (INSA) and Royal Society (Incoming Short Visit 2005/R3), and the Director, Birbal Sahni Institute of Palaeobotany for travel support (to B.N.J.). We thank Anthony Hallam (University of Birmingham) for discussion, Aruna Mistry (University of Birmingham) and Suresh C. Pillai (Birbal Sahni Institute of Palaeobotany) for technical assistance. Professors W. G. Chaloner and D. J. Batten are thanked for positive and constructive reviews on the manuscript. References Biswas, S.K., 1977. The Mesozoic rocks – stratigraphy of Kutch. Quarterly Journal of Geological Mining and Metallurgical Society of India 49, 1–51. Bose, M.N., Banerji, J., 1984. The fossil Xoras of Kachchh. I. Mesozoic megafossils. Palaeobotanist 33, 1–189. Bose, M.N., Sukh-Dev, 1961. Studies on the fossil Xora of the Jabalpur Series from the South Rewa Gondwana Basin – 2. Onychiopsisis paradoxus n. sp. Palaeobotanist 8, 57–64. Burger, D. 1995. Timescales 8. Jurassic. Australian Phanerozoic Time Scales Biostratigraphic Charts and Explanatory Notes. Second Series. AGSO Record 37, pp. 1–30. Deng, S., 1995. Early Cretaceous Xora of Huolinhe Basin, Inner Mongolia, northeast China. Geological Publishing House, Beijing. 1–125, 48 pls (in Chinese with English summary). Deng, S.H., Chen, F., 2001. The Early Cretaceous Filicopsida from northeast China. Geological Publishing House, Beijing. 1–249, 124 pls. Harris, T.M., 1961. The Yorkshire Jurassic Flora. I Thallophyta–Pteridophyta. British Museum (Natural History), London, pp. 1–212. Jaitley, A.K., Singh, C.S.P., 1983. Discovery of Late Bajocian Leptosphinctes Buckman (Jurassic Ammonitina) from Kachchh, Western India. Neus Jahrbuch für Geologie und Paläontologie 2, 91–96. Maheshwari, H.K., Jana, B.N. 2004. Spores and pollen of the Ptilophyllum Flora of Kutch Basin, India. In: Srivastava, P.C. (Ed.). Vistas in Indian Palaeobotany and Plant Morphology: Evolutionary and Environmental Perspectives. Professor D.D. Pant Memorial Volume. U.P. OVset, Lucknow, India, pp. 207–219. Mathur, Y.K., 1972. The plant fossils from the Kuar Bet, Patcham Island, Kutch. Current Science 41, 488–489. Nath, Raj, 1932. A contribution to the stratigraphy of Cutch. Quarterly Journal of the Geological Mining and Metallurgical Society of India 4, 162– 174. Nath, Raj, 1942. Jurassic rocks of Cutch – their bearing on the stratigraphy of some problem of Indian Geology. Proceedings of the Indian Science Congress 29, 93–106. Pandey, J., Dave, A., 1993. Studies in Mesozoic Foraminifera and chronostratigraphy of Western Kutch Gujarat. Palaeontographica Indica 1, 1–219. Patra, B.P., 1990. On some species of Coniopteris occurring in the Athgarh Sandstone, Cuttack district, Orissa. Proceedings of the 77th Indian Science Congress, Cochin 3, pp. 30–31. Venkatachala, B.S. 1970. Palynology of the Mesozoic sediments of Kutch, W. India. 7. Reworked Permian pollen from the Upper Jurassic sediments – a discussion. Palaeobotanist 18, pp. 45-49. Waagen, W., 1875. Abstract of results of the results of examination of the ammonite fauna of Kuch with remarks on their distribution among the beds and probable age. Records of the Geological Survey of India 4, 89–101. Wynne, A.B., 1872. Memoir on the geology of Cutch to accompany a map compiled by A.B. Wynne and F. Fedden, during the seasons 1867–68, 1868–69. Memoirs of the Geological Survey of India 9, pp. 1–289.