Trace elements and rare earth elements in ground ice in kimberlites and sedimentary rocks of Western Yakutia

Trace elements and rare earth elements in ground ice in kimberlites and sedimentary rocks of Western Yakutia

Cold Regions Science and Technology 123 (2016) 140–148 Contents lists available at ScienceDirect Cold Regions Science and Technology journal homepag...

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Cold Regions Science and Technology 123 (2016) 140–148

Contents lists available at ScienceDirect

Cold Regions Science and Technology journal homepage: www.elsevier.com/locate/coldregions

Trace elements and rare earth elements in ground ice in kimberlites and sedimentary rocks of Western Yakutia S.V. Alexeev, L.P. Alexeeva ⁎, A.M. Kononov Institute of the Earths Crust, Siberian Branch of Russian Academy of Sciences (SB RAS), 128 Lermontov Street, Irkutsk 664033, Russia

a r t i c l e

i n f o

Article history: Received 9 April 2014 Received in revised form 31 March 2015 Accepted 1 October 2015 Available online 31 October 2015 Keywords: Structure-forming ground ice Permafrost Trace elements Rare earth elements (REEs) Ground ice salinity Sedimentary rocks and kimberlites

a b s t r a c t The paper presents unique results of studying the composition of the ground ice (major components, trace elements, and rare earth elements — REEs) encountered at a depth of 200–250 m in sedimentary and magmatic rocks in the Western Yakutia diamond-bearing regions. In addition to those established earlier, three new geochemical types of ground ice have been defined: (i) sulfate-hydrocarbonate, (ii) chloride-hydrocarbonate, and (iii) sulfate-chloride types with mixed cation composition. The ground ice geochemical features are caused by evolutionary processes of interaction in the water–rock system during permafrost formation. The enclosed rocks were the source for the addition of sulfate and chlorine ions, as well as trace elements, to the ground waters of the active water exchange zone that had existed before freezing. The distribution pattern of REEs in ground ice has a special form distinct from that of sedimentary rocks, kimberlites, and ocean waters, but similar to the REE pattern in local river waters. This REE pattern features the positive europium (Eu) anomaly and approximate equality of light and heavy REEs. The obtained results essentially expand the insight into ice-formation processes in sedimentary and magmatic rocks. © 2015 Published by Elsevier B.V.

1. Introduction By now, there are numerous publications on the processes of ground-ice formation. However, the specific genetic types of ground ice are poorly understood, such as a special group of ground ice forming at great depths in sedimentary and magmatic rocks. Generally, iceformation processes within bedrocks are analyzed by Krivonogova, 1976; Shumskii, 1964; Velmina, 1965; Vtyurin, 1975. However, the specific data on the occurrence, structure, and chemical composition of ground ice are scarce. The first data were obtained during diamond prospecting in the central part of the Yakutia diamond-bearing province (Alexeev and Alexeeva, 2002; Alexeev and Borisov, 1985; Alexeev and Pinneker, 2000; Ustinova, 1964). There were established the basic geochemical types of ground ice: НСО3, НСО3–Cl и Cl. In 2004–2013, during additional exploration of the primary diamond deposits, the authors collected a unique material that allowed us to supplement and expand the insights into ground ice formation in hard rocks. The objectives of this paper are the indications and analysis of the main geochemical properties of ground ice of sedimentary rocks and kimberlites. This research is based on the concept of ground ice as a complex physical and chemical system whose formation and evolution are the result of freezing of rocks and ground waters. This paper is aiming also to extend the database for trace elements and REE content

⁎ Corresponding author. E-mail address: [email protected] (L.P. Alexeeva).

http://dx.doi.org/10.1016/j.coldregions.2015.10.008 0165-232X/© 2015 Published by Elsevier B.V.

in the deep ground ice that will help to evaluate evolutionary processes in the water–ice–rock system. 2. Study area The study area belongs to the Verkhnemunskiy, Daldyn-Alakitskiy, and Srednemarkhinskiy diamond-bearing regions (Fig. 1) located in the Republic of Sakha (Yakutia). 2.1. Verkhnemunskiy diamond-bearing region The region is situated in the basin of the Muna River (the left tributary of the Lena River). The regional relief is gently wavy with a watershed elevation of 300–400 m. The sedimentary part of the geological section represented by Vendian, Cambrian, and Ordovician terrigenous– carbonate strata is composed of aleuritic–clay–carbonate rocks (dolomites, clay limestones, marls, quartz sandstones) and is broken through by the Middle Paleozoic kimberlite pipes and by the Permian– Triassic trapp intrusions. The permafrost thickness is 240–287 m (Alexeev, 2009). 2.2. Daldyn–Alakitskiy diamond-bearing region The region is in the basin of the Markha River headwaters (the left tributary of the Vilyuy River). The relief represents a dissected plateau with an elevation of 600–700 m. Some areas with trappean massifs and local elevations have greater heights.

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Fig. 1. Location of the Western Yakutia diamond-bearing regions: I — Verkhnemunskiy, II — Daldyn-Alakitskiy, III — Srednemarkhinskiy.

In the 2.4–3.0 km sedimentary mantle, two structural stages divided by a long hiatus were distinguished: the Vendian–Lower Paleozoic and the Upper Paleozoiс–Lower Mesozoic. The former contains kimberlite bodies; the latter overlays them. The Vendian–Lower Paleozoic structural level is composed of monoclinally occurring carbonate strata of the Vendian, Cambrian, Ordovician, and Silurian deposits. The rocks are represented by fissured limestones, sandy dolomites, and marls, and a significant part of the section contains clay limestones and dolomites. The Upper Paleozoic–Lower Mesozoic structural level is formed by the Carboniferous–Permian terrigenous deposits (siltstones with argillite interlayers, coal–clay shales, conglomerates) overlying the Lower Paleozoic carbonate basement. The magmatic structures are represented by pipe-like bodies, and, more rarely, Middle Paleozoic dykes and veins as well as by the Permian–Triassic dolerite sills. The perennial permafrost thickness in the region varies from 70 m in the river valleys to 670 m at the watersheds (Alexeev, 2009).

2.3. Srednemarkhinskiy diamond-bearing region The region is in the middle course of the Markha River at the interstream of the Nakyn and Khannya tributaries. The relief represents an erosion-denudation, gently wavy, weakly dissected plateau with wide plane watersheds and gentle slopes. The elevation of watersheds varies from 220 to 270 m. The erosion depth is 40–60 m. In the 3.5–4.0 km sedimentary mantle, the Vendian–Paleozoic and Mesozoic structural levels were distinguished. The Vendian–Lower Paleozoic level includes Cambrian and Ordovician terrigenous and terrigenous–carbonate rocks. Clay limestones, dolomites, and siltstones prevail along the section; a fine interbedding of clay and carbonates is often observed; fractures filled with gypsum and carbonate clay are reported. The sedimentary strata are broken through by Middle Paleozoic kimberlite pipes and Permian–Triassiс trapp intrusions. The terrigenous rocks of the Mesozoic structural level (Lower Jurassic sandstones, siltstones, and argillites) overlie the Lower Ordovician and Upper Cambrian terrigenous–carbonate rocks. The permafrost

thickness in the region varies from 90 m in the river valleys to 400 m at the watersheds (Klimovskii and Gotovtsev, 1994). 3. Methods Ground ice was studied within kimberlite pipes and in enclosing sedimentary strata of the Paleozoic and Mesozoic ages. The data on the cryogenic structure of rocks were obtained from core logging of boreholes, drilled without application of water flush. The samples of ground ice were collected in intervals according to sampling recommendations and preparation for chemical analysis (Ivanov, 1998). Ice melting was conducted in special polyethylene bags; the solution was then filtrated (Millipore, S 0.22 μm GV), put in plastic bottles, and delivered to a laboratory. The major ice melt components were analyzed at the Institute of the Earth's Crust SB RAS, Irkutsk, by standard techniques (Hydrogeochemistry Reference Book, 1989; Reznikov et al., 1970): the cation concentrations (K+, Na+, Li+, Rb+, Cs+, Sr2+) were measured by flame photometry on the atomic-absorptive spectrophotometer, the anion content (as well as Ca2+, Mg2+) was titrimetrically analyzed, and the sulfate content was determined by turbidimetric and gravimetric analyses. The content of trace elements and REEs was measured in the Baikal Analytical Center of Siberian Branch of Russian Academy of Science (Irkutsk) by ICP-MS (mass spectrometry with inductively coupled plasma) at ELEMENT-2 (Finnigan MAT, Germany). The measurement accuracy was controlled by certified solutions of IQC-026 (Combined Quality Control Standard, ULTRA Scientific, NIST, USA) and XCertiPUR (ICP Multi Element Standard Solution, Merck). 4. Results 4.1. Genetic types of ground ice It is known that the formation of ground ice in sedimentary and magmatic rocks requires water capable of crystallizing under natural cooling conditions. The existing rock fracture net determines the size,

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shape, orientation, and location of ice bodies. The following genetic types of ice-crystal connections within hard rocks are well known in Russian geocryology: cement (pore), intrusive, segregated, wedge, and sublimated (Krivonogova, 1976; Shumskii, 1964; Vtyurin, 1975; Vtyurina and Vtyurin, 1979). These ground ice forms some types of cryostructures in solid and semi-solid rocks: fissured, fissured-veiny, stratal-fissured and stratal-fissured-karst (French, Shur, 2010; Melnikov and Spesivtsev, 2000). In Western Yakutia, cement and intrusive ground ice has the widest spatial development. They are typical of the jointed rock massifs frozen under conditions of rock water saturation beneath the layer of annual temperature fluctuation. Other genetic ground ice types are either absent or minor. These types of ground ice have distinctive features, but their chemical composition is the same. The formation mechanism of cement and intrusive ice was proposed in details earlier (Alexeev, Alexeeva, 2002). In this paper we describe it only in general terms. Free groundwater penetrating down to a depth of 250 m and even to 600 m resulted in the formation of cement ice. Water crystallization in an open system does not change the fracture sizes, but increases in volume by ~9% in a closed system. In sedimentary rocks, the cement ice is mainly formed within the horizontal and/or gently dipping bedding planes. Lenses of ice are typical of the contact zones between rocks of different lithological composition: for example, clayey and dolomitic limestone, limestone and marl, etc. The thickness of alternating lenses of ice is 0.01–0.02 m, but sometimes it reaches 0.05–0.1 m. In zones of tectonic squeezing cement ice fills shear fractures, numerous pores and cavities. The lenses ice thickness here varies from 0.005 up to 0.12 m (Fig. 2). As a rule, cement ice is pure and transparent with a small amount of air bubbles released from water during freezing. It is almost free of mineral admixtures. The development of intrusive ice requires ground water capable of transmitting a hydrostatic pressure and thereby causing intrusion into the freezing and frozen rocks. The hydrostatic and hydrodynamic pressures appear due to closed system freezing of water in rocks or aquifers. As a result, fractures are formed during the injection of ground water, which subsequently transforms into ice. Systems of open fractures and cavities, often under a vacuum, are important in determining the possibility of intrusive ground ice formation. Intrusive ice lenses of considerable thickness may form in them at the initial influx of water. Once formed, ice lenses filling the rock fractures disrupt further ground water movement and create new opportunities for ground ice to form. Conditions for ground ice formation existed in the tectonic zones of the sedimentary rocks and within the kimberlite pipes. Wedges of ice, with thickness of 0.5–1.5 m and sometimes up to 3 m, fill shear fractures of 0.15–0.20 m wide (Fig. 3).

soluble salts is low (0.20–0.45%), with domination of MgCO3 over carbonates down the section, and the рН is 7.2–7.3. The shortage of samples from the Botuobinskaya pipe kimberlites does not allow us to generally characterize the change in the ground ice composition with depth. The two ice samples only give us an idea about their geochemical properties at about 80 m. The ice chemical composition is hydrocarbonate or chloride–hydrocarbonate calcium or magnesium–calcium with a high sodium content (25–27% meq). The ice salinity is 113–155 mg/L. Within the Zarnitsa and Yakutskaya kimberlite pipes (DaldynAlakitskiy diamond-bearing region), the ground ice composition is hydrocarbonate, hydrocarbonate–chloride, and chloride (Alexeev and Alexeeva, 2002; Alexeev and Borisov, 1985; Alexeev and Pinneker, 2000). The cation composition is mixed calcium–magnesium or magnesium–calcium. Down to 130–150 m, the ground ice salinity does not exceed 100–400 mg/L. From 160–180 m, it increases up to 1000 mg/L, and, within the depth interval 180–220 m, it reaches 6500– 12000 mg/L.

4.2.1. Major components in ground ice

4.2.1.2 . Sedimentary rocks. New data were obtained when drilling wells in the Daldyn-Alakitskiy and Srednemarkhinskiy diamond-bearing regions. The D4, D5, D12, and D14 ice samples were collected from the Carboniferous terrigenous sedimentary rocks and from the Lower Silurian and Ordovician carbonates in the Yubileynaya kimberlite pipe (Daldyn-Alakitskiy diamond-bearing region). The ground ice has a sulfate–hydrocarbonate magnesium–calcium composition within the depth intervals of 103–123 and 205–225 m. The chlorine abundance does not exceed 9 mg/L or 6% meq (Table 1). The ice melt salinity is 190–299 mg/L. In the Lower Jurassic and Lower Ordovician terrigenous– sedimentary rocks in the Srednemarkhinskiy diamond-bearing region, the ground ice was studied to a depth of 130 m (Н2–Н7 samples). Within the depth interval 14.0–17.5 m, the ground ice composition is sulfate–hydrocarbonate sodium–calcium. The ice salinity is 268 mg/L, with the chlorine content being 30.5 mg/L (17% meq). Down the section, there is a regular increase of the liquid phase salinity, and a change in the chemical composition of the ground ice (Table 1). At 26.5 m deep, the composition of ice samples is chloride– hydrocarbonate sodium–calcium. The ice salinity is 347 mg/L, the sulfate-ion content is 64 mg/L (26%-meq). Within the depth intervals of 41.5–43.5 and 59–77.5 m, sulfate and chloride salts prevail in the ground ice composition. The salinity increases up to 880–900 mg/L. From a depth of 118 m, the composition of samples is only chloride magnesium–calcium. The ice salinity reaches 1340–3130 mg/L. The sulfate-ion content is 208–237 mg/L (9–19% meq). Thus, based on the obtained results, we can define three new geochemical types of ground ice in the sedimentary rocks: (i) sulfate– hydrocarbonate, (ii) chloride–hydrocarbonate, and (iii) sulfate– chloride types with mixed cation composition.

4.2.1.1 . Kimberlites. Geochemical properties of the ground ice in kimberlite were studied within the Novinka pipe (samples М1–М6 and А1) and the Botuobinskaya pipe (samples Н8 and Н9) (Table 1). In the Novinka pipe, the composition of ice is predominantly chloride–hydrocarbonate calcium–magnesium and more rarely calcium–sodium down to a depth of 55 m. There are almost no sulfates. The salinity varies from 63 to 218 mg/L. Within 55–57 m, the composition changes into hydrocarbonate–chloride, and calcium dominates among the cations (38% meq). The salinity is 244 mg/L. The chemical composition of aqueous extracts from kimberlites also showed the prevalence of Mg over other cations down to a depth of 150 m, which correlates with the ground ice composition. The anion content of the extracts, in contrast, is different from the ice composition and is hydrocarbonate–sulfate down to a depth of 65 m; deeper, it becomes sulfate–chloride and chloride–sulfate. The total content of water-

4.2.2. Trace elements in ground ice To estimate the content level of trace elements and reveal the patterns of their distribution, the authors for the first time measured contents of more than 40 elements in the ground ice of kimberlites and sedimentary rocks. Table 2 shows the comparison between the contents of trace elements in ground ice and in the Sytykan River water (a Daldyn River tributary). We averaged the concentration values for each trace element in ground ice at various depths, and built the distribution curves of the mean trace element content in the ground ice for kimberlites (two curves), sedimentary rocks (two curves), and river water (one curve) (Fig. 4). Analysis of the curves demonstrated that, in general, a lower trace element content is typical of the ground ice in kimberlite as compared with that in the sedimentary deposits. Exceptions are P, Ti, Cu, Zn, Y,

4.2. Chemical composition of ground ice

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Fig. 2. Examples of cement ice in the sedimentary rocks sampled at different depths in the Yakutian diamond-bearing province. Photo: S.V. Alexeev.

Zr, Pb, and Th, whose mean concentration exceeds that in the enclosing rocks 2–45 times. The patterns of the trace element distribution in the sedimentary deposit ground ice basically correspond to their distribution in kimberlite ice. One can observe the most significant deviations towards content

excess for Br, Sr, Mo, Cd, Sb, W, Re, and U, and a smaller concentration is typical of Cr, Nb, Hf, and Th. A significant enrichment of the ground ice in sedimentary rocks of the Daldyn-Alakitskiy region is detected only for Al, Ti, Fe (more than 10-fold), and Sn (almost 50-fold). In the sedimentary rock ice of the Srednemarkhinskiy region a higher concentration of

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Fig. 3. Examples of intrusive ice in the sedimentary rocks (a) and kimberlites (b) sampled at different depth in the Yakutian diamond-bearing province. Photo: S.V. Alexeev.

Co, Ni, Ge, As, Sb, Sr, and U is detected, and the Br content here is the highest. A synchronous change in the content of most trace elements is typical of the kimberlite ground ice in the Srednemarkhinskiy and Verkhnemunskiy diamond-bearing regions. The difference in the content of some of them denotes the specific conditions of the trace element accumulation during the water–rock interaction. Thus, the Botuobinskaya pipe ground ice is enriched with Al, Mn, Co, Y, and Zr more than 10-fold, and with Zn, Mo, Cd, Sb, Th and U more than three-fold in comparison with the Novinka pipe ice, but is depleted in Fe and Bi manyfold. Apparently, this depends on the petrochemical properties of these pipes' kimberlites. The Novinka pipe kimberlites belong to the kimberlite formation petrotype, in which a moderately higher content of high-charge rare and radioactive elements is typical. The Botuobinskaya pipe kimberlites belong to the kimberlite geochemical type that features a negative anomaly of high-charge rare and

radioelements, and also a decreased concentration of Ti and lower values of Сe/Y, Nb/Zr, and Th/U (Lapin et al., 2007). One can see the ground ice enrichment in nearly all the trace elements (Li, B, Ti, Mn, Fe, Ni, Br, Rb, Sr, Mo, Sb, W, Pb, Bi, and Th) over river waters (the Sytykan River water). Exceptions are Sc, Cr, and Hf, whose concentration in the river water is below the test limit. 4.2.3. REEs in ground ice The rare earth element (REE) abundance in ground ice of the Western Yakutia diamond-bearing regions generally varies from 0.0001 μg/L for heavy REEs to 0.57 μg/L for light REEs (Table 3). For the kimberlite ground ice, the REE concentration is increased 1.5–5 fold as compared with that of the sedimentary rocks ground ice, and there is enrichment in lighter REEs (La–Sm). The enrichment of the kimberlite ground ice in rare elements is 1.5–10-fold, whereas the sedimentary rocks ground ice has an REE

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Table 1 Major components in ground ice of the Western Yakutia diamond-bearing regions. Ice sample

Depth, m

рH

TDSa, mg/L

Component, mg/L K+

Na+

Br−

SO2− 4

HCO− 3

5.7 10.3 3.6 27.3 7.1 75.2 18.4

0.2 0.2 b0.1 0.1 b0.1 0.9 0.2

b2 3.0 b2 4.0 b2 b2 2.0

136.7 145.2 45.2 133.0 90.3 94.0 61.0

176.1 200.4 63.2 217.9 126.7 244.0 143.2

37.1 17.3 46.1 72.5

9.2 5.7 44.3 28.4

0.1 b0.1 − −

43.0 18.0 77.0 182.5

180.6 122.0 91.5 70.8

299.2 190.4 291.3 377.8

10.3 15.2 50.5 42.6 90.0 255.4

30.1 40.1 112.2 145.3 172.3 430.9

21.6 63.1 310.2 221.6 615.1 1763.1

b0.1 − − − − 21.5

30.5 64.6 211.9 257.6 207.8 237.5

146.5 119.6 83.0 141.6 100.1 63.5

267.9 346.7 879.8 901.3 1340.5 3133.9

9.4 4.3

17.0 12.0

37.2 14.2

10.0 10.0

61.0 61.0

155.2 113.7

Mg2+

Ca2+

Verkhnemunskiy diamond-bearing region (kimberlites) М1 2–2.5 7.4 2.0 М2 3.8–4.3 7.1 3.6 М3 12–14 7.2 1.6 М4 18.5–20 7.0 4.6 М5 38–39.7 7.0 3.3 М6 55–56.5 7.1 11.6 А1 42–52 9.4 19.0

2.0 2.7 1.0 14.5 3.1 18.1 28.6

24.7 26.5 5.5 21.3 9.61 15.2 0.7

4.8 8.8 6.4 13.0 13.2 29.1 5.6

Daldyn-Alakitskiy diamond-bearing region (sedimentary rocks) D12 103–123 7.7 3.3 D14 221–228 8.2 15.7 D4 205 7.4 8.3 D5 217 7.8 3.3

10.5 1.5 5.9 5.1

15.4 10.2 18.2 15.2

4.7 5.6 11.2 18.6 23.3 43.2

24.3 38.5 100.8 74.1 131.9 310.0

6.3 3.2

14.3 9.0

Srednemarkhinskiy diamond-bearing region Sedimentary rocks Н2 14–17.5 7.5 Н3 26.5 7.7 Н4 41–43 b8.0 Н5 59–77 7.8 Н6 118–119 b8.0 Н7 129–130 b8.0 Kimberlites Н8 79 7.6 Н9 81 7.1 a

Cl−

− −

Total dissolved solids.

concentration comparable to that in the river water. The exception is cerium (Ce), which has a negative anomaly in the river water. It is probably caused by geochemical peculiarities of this element: cerium with a valence of Ce4+ is close, in terms of its behavior, to thorium, hafnium, zirconium, and titanium (Dubinin, 2006), whose abundance in the Sytykan River water is negligible (Table 3). A common pattern for ground ice and surface waters is a high Eu content and its positive anomaly on the REE distribution pattern (Fig. 5). Concerning ocean waters, the light REE abundance in the ground ice of kimberlites and sedimentary rocks is, on average, two times higher, while the heavy REE abundance is 10 times higher. The negative Ce anomaly typical of ocean water is not exhibited in ground ice. When comparing the REE content in ground ice with that in sedimentary rocks and kimberlites, one can distinctly find not only an enormous difference in the REE absolute content (of hundreds of, and even ten-thousand, orders of magnitude), but also their totally dissimilar distribution patterns. A gentle subhorizontal REE pattern is typical of sedimentary rocks, but an essential prevalence of light REEs whose concentration reaches 86 (La) and 170 (Ce) μg/kg is observed in kimberlites. The light and heavy REE concentrations are almost equal in kimberlites, whereas a slight excess of heavy lanthanides over the light ones is determined in the sedimentary rocks ground ice. 5. Discussion Generally, the geochemical properties of ground ice were inherited from the environment that existed at the beginning of the cooling epoch. Enrichment of the samples in sulfate and chloride salts testifies to this. Analyses of water extracts confirm that sulfate and chlorine in the ground waters of the active water exchange zone were most likely supplied by enclosing rocks. The presence of sulfate and chloride salts in rocks is connected with the formation of sedimentary strata and kimberlite pipes. In the Paleozoic and Early Mesozoic, marine basins occupied vast areas on the Siberian Platform (Geology, hydrogeology.., 1986). During evaporation in the halogenic basins, limestones, dolomites, marls, and terrigenous

material (sandstones, siltstones, etc.) had been deposited. These sediments featured significant salinization and accumulated compounds with a high solubility potential. They were not only soluble compounds (calcium and magnesium carbonates, gypsum and anhydrite, trace halite, etc.), but also rock-saturating solutions and exchange cations in the absorbing state. A higher chloride and sodium content in the ice-forming water composition was, probably, also connected with a complex pattern of the magmatic melt injection into the sedimentary host rocks of marine or coastal genesis, or with the composition of the kimberlite breccia containing xenoliths of salinized sedimentary rocks; the percentage of xenoliths is sometimes up to 90% of kimberlite breccias (Zinchuk, 2011). Before the cooling epoch, the interaction between ground waters and rocks was accompanied by the transition of the easily soluble salts into the liquid phase, and led to increase in the mainly chlorine and sodium content. Perennial freezing of rocks in the Late Cenozoic caused the formation of ground ice and rearrangement of the hydrogeochemical zonality. Its influence was most distinctly reflected in hydrocarbonate waters. During cryochrons, deep cooling of rocks was accompanied by increases in the ground water concentration and precipitation of carbonate and sulfate salts in easily soluble compounds in ground ice. Trace element enrichment or depletion of ground ice is directly connected with the primary composition of the groundwater-saturated rocks. For example, an increased clayiness of the sedimentary rocks in the Daldyn-Alakitskiy diamond-bearing region provided Al, Ti, and Fe accumulation in ground waters. The high trace element concentration in the sedimentary rocks ground ice in the Srednemarkhinskiy region is connected, most likely, with the presence of brown coal interlayers in the Jurassic strata. Trace elements are present in coals as mineral admixtures (clay minerals, salts of alkali metals and iron, higher Ge, U, and W content, etc.). The interaction of groundwater with the Jurassic coaly terrigenous sedimentary rocks caused the leaching of trace elements. The REE distribution in ground ice does not inherit the REE distribution in either kimberlites or sedimentary rocks. A NASC-normalized REE pattern is remarkable for a Eu positive anomaly in ground ice. The mean

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Table 2 Mean trace element content (μg/L) in the ground ice of the Western Yakutia diamond-bearing regions and in river water (dash — no data). Trace elements

Li B Al Si P S Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Rb Sr Y Zr Nb Mo Ag Cd Sn Sb Cs Ba Hf Ta W Re Au Tl Pb Bi Th U

Verkhnemun-skiy diamond-bearing region (kimberlites)

Daldyn-Alakitskiy diamond-bearing region (sandstones, limestones)

Srednemarkhinskiy Diamond-bearing region sandstones, limestones, dolomites

Kimberlites

6.89 221.08 34.45 791.43 48.80 3327.9 0.02 2.92 1.3 2.83 7.82 104.33 0.23 7.57 3.66 5.05 0.02 0.008 0.58 0.18 437.3 4.44 391.1 0.04 0.13 0.02 0.69 0.01 0.02 – 0.14 0.009 46.53 0.003 0.0005 0.22 0.0012 0.015 0.048 1.80 0.034 0.028 0.06

49.35 665.93 168.6 733.84 11.65 – 0.03 5.26 1.13 0.49 18.54 75.55 0.73 5.08 1.71 5.73 0.2 0.03 0.86 0.18 306.83 14.16 678.1 0.04 0.21 0.01 45.38 0.01 0.45 1.1 1.42 0.09 37.01 0.01 0.0008 1.46 0.02 – 0.03 0.04 – 0.01 0.75

129.12 882.36 9.48 1611.73 7.38 75352 0.09 0.46 3.31 0.19 104.62 3.31 10.4 45.57 2.22 7.94 0.1 0.14 11.47 1.38 9914.72 23.59 3446.43 0.03 0.04 0.002 56.85 – 0.02 0.02 0.14 62.29 0.001 0.73 – 0.14 0.05 – 0.12 0.05 0.02 0.02 5.28

17.95 163.35 237.15 654.05 39.4 – – 15.95 1.2 – 100.55 19.45 2.7 – 6.78 16.2 0.16 – – – – 10.17 351.2 0.65 1.6 – 1.73 – 0.07 – 0.64 0.14 6.57 – – – – – 0.06 0.88 0.01 0.22 0.18

The Sytykan River water 11.7 63 9.3 865 9.8 5099 0.64 0.42 0.37 0.75 2.49 4.72 0.07 1.24 3.1 9.9 0.004 0.49 0.44 – 172 1.14 195 0.03 0.18 0.001 0.39 – – 0.02 0.29 0.003 65 0.005 – 0.06 0.001 – – 0.04 0.0004 0.001 0.48

Fig. 4. Mean trace element content in ground ice for kimberlites and the sedimentary rocks of the Western Yakutia diamond-bearing regions. In kimberlites: 1 — Srednemarkhinskiy diamond-bearing region, the Botuobinskaya pipe; 2 — Verkhnemunskiy diamond-bearing region, the Novinka pipe; in the sedimentary rocks: 3 — Srednemarkhinskiy diamond-bearing region, the Nakyn and Khannya interfluve; 4 — Daldyn-Alakitskiy diamond-bearing region, the Markha River head and the Daldyn River middle course; 5 — the Sytykan River water.

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Table 3 REE abundance (μg/L) in the ground ice, kimberlites and sedimentary rocks of the Western Yakutian diamond-bearing regions, river and ocean waters (bdl — below detection limit). Depth, m

La

Ce

Pr

Nd

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

0.032 0.0052 0,0022 0,0055 0,0038 0.003 0.0048

0.01 0.0045 0,0011 0,0043 0,011 0.0033 0.011

0.038 0.0052 0,0026 0,0073 0.0042 0.0033 0.0051

0.0059 0.0007 0,0004 0,001 0.0006 0.0005 0.0003

0.036 0.0038 0,0022 0,0044 0.0034 0.0025 0.0036

0.0065 0.0007 0,0004 0,0007 0.0005 0.0005 0.0005

0.017 0.0017 0,0008 0,0018 0.0015 0.0007 0.0017

0.0026 0.0003 bdl 0,0003 0.0002 0.0002 0.0003

0.016 0.0016 0,0009 0,0018 0.0016 0.0012 0.0016

0.0023 0.0003 bdl 0,0003 bdl 0.0002 0.0003

Daldyn-Alakitskiy diamond-bearing region: ice in sedimentary rocks (limestones, sandstones) 11 3 bdl bdl 0.0004 0.0077 bdl 0.0013 0.0003 167 0.028 0.063 0.0057 0.027 0.0068 0.0017 0.0011 171 0.039 0.1 0.011 0.05 0.011 0.0037 0.0021 224.5 0.05 0.11 0.015 0.059 0.015 0.012 0.0022 205 0.025 0.059 0.007 0.039 0.007 0.003 0.0059 217 0.003 0.004 0.0006 0.004 0.0015 0.0037 0.0014

0.0012 0.0069 0.012 0.016 0.0014 0.0000

0.0028 0.0068 0.01 0.013 0.008 0.0002

0.0012 0.0013 0.0018 0.0021 0.0017 0.0001

0.0044 0.004 0.0055 0.0048 0.004 0.0014

0.0007 0.0007 0.0006 0.0008 0.0014 0.0000

0.0044 0.0039 0.0044 0.0038 0.0052 0.0007

0.0009 0.0009 0.0008 0.0007 0.0009 0.0000

Srednemarkhinskiy diamond-bearing region: a) ice in sedimentary rocks (sandstones) 15.75 0.0079 0.011 0.0015 0.0064 0.003 0.012 0.0013 26.5 0.0061 0.0047 0.0006 bdl bdl 0.011 bdl 42.5 0.0091 0.0078 0.0009 0.0045 0.0011 0.0059 0.0009

0.0006 bdl bdl

0.0023 0.0011 0.0009

0.0011 0.0007 bdl

0.0016 0.0009 0.0011

0.0006 0.0004 0.0002

0.0014 0.0008 0.0008

0.0004 0.0004 bdl

b) ice in sedimentary rocks (limestones. dolomites) 68 0.011 0.0032 bdl 0.0031 118.5 0.019 0.019 0.0018 0.01 130 0.015 0.0089 0.0012 0.014

bdl 0.0011 0.0013

0.0045 0.0058 0.0064

0.0007 0.0019 0.0015

bdl 0.0003 0.0002

bdl 0.0016 0.0014

bdl 0.0003 0.0005

bdl 0.001 0.0026

bdl 0.0003 0.0005

bdl 0.0011 0.0019

bdl 0.0003 0.001

Kimberlites (Balashov, 1976) 86.0 170.0

10.5

2.6

7.5

1.2

4.1

0.8

1.9

0.3

1.6

0.2

Sedimentary rocks of platforms (Balashov, 1976) 21.00 39.00 4.90 19.00

4.30

0.80

3.60

0.60

2.70

0.65

1.80

0.27

1.50

0.23

Sytykan River water (Western Yakutia) 0.008 0.0082 0.0017

0.011

0.0032

0.0052

0.0034

0.0005

0.0034

0.0012

0.0034

0.0005

0.0041

0.0005

Pacific ocean water (Zhang and Nozaki, 1996) 0.00067 0.00020 0.00013

0.00067

0.00020

0.00006

0.00026

0.00005

0.00035

0.00009

0.00029

0.00004

0.00021

0.00003

Verkhnemunskiy diamond-bearing region: ice in kimberlites 2.25 0.16 0.38 0.038 0.16 4 0.049 0.08 0.0076 0.028 13 0.026 0,039 0,0045 0,013 19,3 0,062 0,1 0,011 0,042 38,7 0,039 0,056 0,0059 0,021 47 0.04 0.064 0.0054 0.017 55.75 0.047 0.079 0.0078 0.024

18.0

72.0

values of Euan = Eu/EuNASC / (1/2 × Sm/SmNASC + 1/2 × Gd/GdNASC) computed for ground ice are significant: 2.1 in kimberlites, 6.2 in sedimentary rocks, and 6.9 (maximum) for river waters.

A similar pattern of the REE distribution with a distinct Eu anomaly is typical of hydrothermal fluids (Dubinin, 2006; Haas et al., 1995). Hence, a high positive Eu anomaly may be an indirect sign of a hyperthermal

Fig. 5. NASC-normalized REE abundance in the ground ice of the Western Yakutia diamond-bearing regions. North American shale composite (Gromet et al., 1984); the data on the REE abundance in kimberlites and sedimentary rocks of platforms (Balashov, 1976), in ocean waters (Zhang and Nozaki, 1996).

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medium during the liquid phase formation, although one cannot exclude the possibility that Eu enrichment was caused by diagenesis of marine sediments under anaerobic conditions. However, considering enormous scales of the alkali-ultrabasic (kimberlite) and alkaline (trappean) magmatism during the Paleozoic–Mesozoic activation of the Siberian Platform, one may assume that REE and Eu accumulation in solutions is due to the changes in basic and ultrabasic rocks during the hydrothermal process. The heating temperature of watersaturated sedimentary rocks in the thermal field of intrusive bodies was 200–800°С (Feoktistov, 1978). In the hydrothermal fluid at 300– 400 °С, europium has the valence Eu2 +. It can substitute for calcium in the structure of the calcium-containing minerals and transit with calcium into a solution (Dubinin, 2006). Besides, because a high Eu content in REEs is typical of alkaline basalts (Balashov, 1976), the Eu anomaly in ground ice may be caused by addition of this element into the liquid phase during the water–trapp interaction. The distribution of certain REEs in ground ice indicates to the climatic environment during the formation of sedimentary rocks. From the ratio of ∑ Сe/∑ Y (where ∑ Се = ∑(La–Gd), ∑ Y = ∑Tb–Lu,Y), one can make a judgment about arid or humid climates in the past. The 2.5–4 value is a marker: a ratio with a value b 2.5 characterizes arid sedimentation conditions, whereas a value N 4 indicates humid ones (Shatrov, 2007). In the ground ice of terrigenous–sedimentary rocks of the study area, ∑ Сe/∑ Y is 1.3 on average. Hence, sedimentation occurred under an arid climate, which is also indicated by an abundant carbonate content and higher rock salinization. 6. Conclusions 1. Deep freezing of the geological section of Western Yakutia led to the formation of ground ice of different geochemical types in sedimentary rocks and kimberlite pipes. Cement and intrusive ice is best developed, other genetic ground ice types are either absent or minor. 2. The geochemical features of the texture-forming ground ice allow to distinguish three new geochemical types of ground ice: (i) SO4– HCO3, (ii) Cl–HCO3, and (iii) SO4–Cl with mixed cation composition. 3. The geochemical properties of ground ice are the result of water– rock interaction that was accompanied by dissolution and transition of carbonate, sulfate, and chloride salts into solution before the permafrost formation. The perennial freezing of rocks determined the present-day features of the hydrogeochemical zonality within the diamond-bearing regions. It also caused salt differentiation between the phases during the freezing of water-saturated rocks, as well as concentration of natural solutions and formation of hydrocarbonate, sulfate–hydrocarbonate, chloride–hydrocarbonate, hydrocarbonate–chloride, sulfate–chloride, and chloride types of ground ice. 4. The trace elements of ground ice reflect the features of the primary composition of ground waters that were enriched in trace elements during interaction with the Cambrian clay-carbonate rocks or Jurassic carbonate terrigenous sedimentary rocks. When these rocks froze in the Late Cenozoic, the ground ice formation essentially transformed the primary composition of solutions by transferring a part of the accumulated trace elements into the intercrystalline space of solid phase. High Li, B, Si, Mn, Fe, Br, and Sr contents along with Sc, Ge, Hf, Ta, Nb, and Th deficits are typical of ground ice. 5. The distribution of REEs in ground ice is peculiar and inherits the REE distribution characteristic of neither the host rocks nor ocean waters. The REE concentration in ground ice is two to four orders of magnitude lower than that in kimberlites and in sedimentary rocks, exceeds the REE abundance in ocean waters by one to two orders of magnitude, and is roughly equal to the REE abundance in river waters. The REE pattern for ground ice of both kimberlites and sedimentary rocks features an Ʌ-shaped pattern, distinct Eu positive

anomaly, and approximate equality of light and heavy REEs. At the same time, the ground ice in kimberlite has higher REE concentrations than the ground ice in sedimentary rocks. Acknowledgments The authors are grateful to colleagues at the Institute of the Earth's Crust SB: A.S. Gladkov, D.A. Koshkarev, and I.A. Potekhina, as well as to the Head Geologists of Aikhal, Nyurba, and Udachny Mining & Processing Division at the JSC “ALROSA”: I.V. Makovchuk, M.A. Karpenko, and G.P. Shmarov, for their help and assistance when conducting field studies in the Western Yakutia diamond-bearing regions. The researches have been carried out with financial support from the Russian Foundation for Basic Research (project 13-05-01075) and project of RAS “ARCTIC” (N 114080820037). We appreciate to reviewer Mikhail Kanevskiy for the helpful comments. References Alexeev, S.V., 2009. Cryohydrogeological Systems of the Yakutian Diamond-Bearing Province. Academicheskoe izd. “GEO”, Novosibirsk (in Russian). Alexeev, S.V., Alexeeva, L.P., 2002. Ground ice in the sedimentary rocks and kimberlites of Yakutia, Russia. Permafr. Periglac. Process. 13, 53–59. http://dx.doi.org/10.1002/ppp. 408. Alexeev, S.V., Borisov, V.N., 1985. Chemical composition of ground ice of Severnaya pipe. Glaciological Researches in Eastern Siberia. Izd. IEC SB RAS, Irkutsk, pp. 129–137 (in Russian). Alexeev, S.V., Pinneker, E.V., 2000. Geochemistry of ground ice in sedimentary strata of Yakutia. Dokl. Akad. Nauk 373 (5), 660–662 (in Russian). Balashov, Yu.A., 1976. Geochemistry of Rare Earth Elements. Nauka, Мoscow (in Russian). Dubinin, A.V., 2006. Geochemistry of Rare Earth Elements in Ocean. Nauka, Мoscow (in Russian). Feoktistov, G.D., 1978. Petrology and Conditions for Forming Trappean Sills. Nauka, Novosibirsk (in Russian). French, H., Shur, Y., 2010. The principles of cryostratigraphy. Earth Sci. Rev. 110, 190–206. http://dx.doi.org/10.1016/j.earscirev.2010.04.002. Gromet, L.P., Dymek, R.F., Haskin, L.A., Korotev, R.L., 1984. The “North American shale composite”. Its compilation, major and trace element characteristics. Geochim. Cosmochim. Acta 48 (12), 2469–2482. Haas, J.R., Shock, E.L., Sassani, D.S., 1995. Rare earth elements in hydrothermal systems: estimates of standard partial molar thermodynamic properties of aqueous complexes of the rare earth elements at high pressures and temperatures. Geochim. Cosmochim. Acta 59, 4329–4350. http://dx.doi.org/10.1016/0016-7037(95)00314-P. Ivanov, A.V., 1998. Cryogenic Metamorphization of Chemical Composition of the Nature Ice, Freezing and Thawing Water. Dal'nauka, Khabarovsk (in Russian). Klimovskii, I.V., Gotovtsev, S.P., 1994. Cryolithozone of the Yakutian Diamond-Bearing Province. Nauka, Novosibirsk (in Russian). Kovalskii, V.V., Bilanenko, V.A. (Eds.), 1986. Geology, Hydrogeology and Geochemistry of Oil and Gas in the Southern Slope of the Anabar Anteclise. Izd-vo YaB SB USSR, Yakutsk (in Russian). Krivonogova, N.F., 1976. Analysis of ice-formation types in bedrocks at engineeringgeological characteristics. Permafrost Researches 15. MSU Publishers, Мoscow, pp. 147–149 (in Russian). Lapin, A.V., Tolstov, A.V., Vasilenko, V.B., 2007. Petrogeochemical peculiarities of kimberlites of Srednemarkhinskiy region in connection with the problem of kimberlite geochemical heterogeneity. Geochemistry 12, 1292–1304 (in Russian). Melnikov, V.P., Spesivtsev, V.I., 2000. Cryogenic Formations in the Earth's Lithosphere (graphic version). Siberian Publishing Center UIGGM, Siberian Branch of the RAS Publishing House, Novosibirsk (in Russian). Nikanorov, A.M. (Ed.), 1989. Hydrogeochemistry Reference Book. Gidrometeoizdat, Leningrad (in Russian). Reznikov, A.A., Mulikovskaya, E.P., Sokolov, I.Yu., 1970. Methods for the Natural Water Analysis. Nedra, Мoscow (in Russian). Shatrov, V.A., 2007. Lanthanides as indicators of chalk phosphorite formation (by example of the East European Platform). Dokl. Akad. Nauk 414 (1), 90–92 (in Russian). Shumskii, P.A., 1964. Principles of Structural Glaciology. Dover Publicatons, New York. Ustinova, Z.G., 1964. On the issue of geochemistry of kimberlites pipes in Yakutia. Issues of Ground Water Geochemistry. Nedra, Мoscow, pp. 237–252 (in Russian). Velmina, N.А., 1965. On genesis of injective ice. Ground ice II. MSU Publishers, Мoscow, pp. 83–90 (in Russian). Vtyurin, B.I., 1975. Ground Ice of the USSR Nauka (Мoscow , in Russian). Vtyurina, E.A., Vtyurin, B.I., 1979. Ice Formation in Rocks. Nauka, Moscow (in Russian). Zhang, J., Nozaki, Y., 1996. Rare earth elements and yttrium in seawater: ICP-MS determinations in the East Caroline, Coral Sea, and South Fiji basins of the western South Pacific Ocean. Geochim. Cosmochim. Acta 60 (23), 4631–4634. http://dx.doi.org/10. 1016/S0016-7037(96)00276-1. Zinchuk, N.N., 2011. Using of standard models of kimberlite pipes in the diamond prospecting. Vestn. VGU Geology. 1, 133–144 (in Russian).