Unique Quaternary Environment for Discoveries of Woolly Rhinoceroses in Starunia, Fore-Carpathian Region, Ukraine: Geochemical and Geoelectric Studies
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Unique Quaternary environment for discoveries of woolly rhinoceroses in Starunia, fore-Carpathian region, Ukraine: Geochemical and geoelectric studies Maciej J. Kotarba* Marek Dzieniewicz AGH-University of Science and Technology, Faculty of Geology, Geophysics and Włodzimierz J. Mo´scicki Environmental Protection, Mickiewicza Av. 30, 30-059 Kraków, Poland Henryk Sechman ABSTRACT purpose of our geochemical and geoelectric studies was to investigate the In 1907, remnants of a mammoth and a woolly rhinoceros were geologic setting and environment of the Pleistocene sediments, as well as to discovered in the Pleistocene clays of an earth-wax mine in Starunia assess the possibility of new discoveries of large, extinct mammals. village. Then, in 1929, a nearly fully preserved woolly rhinoceros was found in the same mine. The unique combination of clays, oil, and FIELD AND ANALYTICAL PROCEDURES brine into which the animals had sunk is responsible for their almost For a near-surface geochemical survey, the patented sampling pro- perfect preservation. During the late Pleistocene winters, when the cedure of Sechman and Dzieniewicz (2007) was used. The sampling ice and snow cover was present in the tundra “paleoswamp,” areas of depth was ~1.2 m. Natural gas samples from wells and surface seeps were infl ow of brines, oils, and hydrocarbon gases had a higher tempera- placed into 500 mL glass vessels fi lled with saturated NaCl solution. The ture, which resulted in melting and cracking of the cover, and large molecular composition of gases was analyzed in a set of columns on gas mammals could be trapped. Geoelectric measurements, as well as chromatographs equipped with fl ame ionization (FID) and thermal con- molecular and stable isotope analyses of gases in the near-surface zone ductivity (TCD) detectors. Stable carbon isotope analyses were performed within the “paleoswamp” performed in 2004–2005, reveal a few places using a mass spectrometer, and results are presented in the δ notation favorable to the burial and preservation of Pleistocene vertebrates. relative to the Peedee belemnite (PDB) standard. The geoelectric method applied was DC resistivity sounding. A four-electrode Schlumberger array Keywords: woolly rhinoceros, ozokerite, Pleistocene, surface geochemi- with the largest spacing, AB/2 = 100 m, was used (Mościcki, 2005). cal survey, DC resistivity, stable carbon isotopes, Ukraine. GEOCHEMICAL STUDY INTRODUCTION In the Starunia area (Fig. 1), gas samples were collected from fi ve The discoveries of large Pleistocene mammals at the Starunia ozokerite wells in Oligocene and Eocene reservoirs and from two oil seeps. The (earth-wax) mine, situated in the fore-Carpathian region in Ukraine (Fig. 1), molecular composition, gas indices, and stable isotope ratios vary within were spectacular scientifi c events on a worldwide scale (e.g., Alexan drowicz, the following ranges (Kotarba et al., 2005a): CH4 85.6%–95.9%, C2H6 2005). In 1907, a partially preserved mammoth was found at a depth of 1.76%–4.78%, C3H8 0.41%–2.20%, N2 0.92%–2.40%, CO2 0.01%–3.49%, 12.5 m, and a woolly rhinoceros at a depth of 17.6 m. In 1929, Polish sci- hydrocarbon CHC index [CHC = CH4/(C2H6 + C3H8)] from 12 to 44, car- entists discovered a unique, nearly complete woolly rhinoceros carcass at a bon dioxide–methane (CDMI) index [CDMI = CO2/(CO2 + CH4)100(%)] δ13 − δ depth of 12.5 m. Radiocarbon dating determined two probable ranges for from 0.09% to 3.92%, C(CH4) from –46.6‰ to 27.1‰, D(CH4) from − − δ13 − − δ13 the age of the remnants of these mammals: one around 42 ka, and another 187‰ to 150‰, C(C2H6) from 33.1‰ to 26.5‰, and C(CO2) around 26 ka (Kuc et al., 2005). The woolly rhinoceros excavated in 1929 from −15.6‰ to +20.0‰. Moreover, slight concentrations of helium, up is displayed at the Natural History Museum in Kraków (Fig. 1). The fossil to 0.011% (N-1 well, Fig. 1) as well as hydrogen (0.25%) in the “upper fl ora and fauna excavated in Starunia in 1907 and 1929 were subjected to oil eye” are present. various scientifi c investigations for identifi cation, determination of ecology, Subsurface hydrocarbon gases accumulated in Oligocene and Eocene age, and other purposes (Alexandrowicz, 2005, and references therein). In reservoirs as well as gases connected with two oil seeps in the Starunia area 2004, Polish and Ukrainian scientists restarted studies in the Starunia area. were generated from type II kerogen during low-temperature thermogenic Quaternary deposits of the Velyky Lukavets River valley in Starunia processes (Figs. 2A and 2C). The thermogenic hydrocarbons migrated are developed as clays containing plant remains and large Pleistocene together with helium (Fig. 3A) to the surface along the “Rinne” fault zone mammals, as well as gravels, sands, and peats. The top of the Lower Mio- directly from deep accumulations (Kotarba et al., 2005a). Carbon dioxide cene Vorotyshcha Salt-bearing Formation of the Boryslav–Pokuttya Unit, is also of thermogenic origin, with the exception of gas from the “upper oil which underlies the Quaternary deposits, occurs at depths from 8 to 20 m. eye,” which was generated during microbial processes (Fig. 2B). The ozokerite deposit occurs in a Miocene molasse sequence. The near-surface geochemical studies were run along three measure- Pleistocene clays were saturated with brines that migrated from the ment lines (Fig. 1, lines P-0, P-2, and P-3). The analyzed gases are more underlying Lower Miocene Vorotyshcha beds rich in halite and sylvite, and variable in their molecular and isotopic compositions than gases from oil from Oligocene and Eocene strata of the Boryslav-Pokuttya Unit (Koltun deep accumulations and seeps (Kotarba et al., 2005a, 2005b). Concentra- et al., 2005; Kotarba et al., 2005a). Small oil seeps and ponds, mud vol canoes, tions of components of near-surface gases for 111 samples are presented in and saltwater springs are present in Starunia and nearby. The almost per- Table 1. Gas indices and stable carbon isotope ratios for 24 selected sam- fect preservation of skin and some soft tissues (e.g., tongue, trachea, palate; ples vary within the following ranges: hydrocarbon (CHC) index 12–4543, δ13 Kubiak, 1969) as well as collagen in bones (Kuc et al., 2005) of the woolly carbon dioxide methane (CDMI) index from 2.3%–100%, C(CH4) from − − δ13 − − δ13 rhinoceros discovered in 1929 was a result of natural processes, owing to 70.9‰ to 32.4‰, C(C2H6) from 29.9‰ to 25.4‰, and C(CO2) the brine- and oil saturation of the “spongy” microporous body structures. from −26.3‰ to +1.9‰. These ranges indicate that genetic history and Unfortunately, the DNA of the rhinoceros has not been investigated yet. The gas migration to the near-surface zone were complicated. The highest concentrations of analyzed gases occur in the central and southeastern *E-mail: [email protected]. parts of the study area, whereas in the northwestern and western parts, © 2008 The Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or [email protected]. GEOLOGY,Geology, July July 2008; 2008 v. 36; no. 7; p. 567–570; doi: 10.1130/G24654A.1; 4 fi gures; 1 table. 567 0 250 km Estonia Russia Oil and gas sample 1 METER Latvia Gas sample DC resistivity survey line Sweden Lithuania Oil sample E-2 BielarusBelarus Oil and gas seep: 00 4 Germany Poland OE-U “Upper oil eye” P-2 Ukraine OE-L “Lower oil eye” Czech Republic 420 Slovakia Overthrust Austria HungarySlovenia Romania Study area OE-U ′″ 24° 25′ E 24o 30’ 24° 35′ ° 48 41 20 MONASTYRCHANY 00 4 410 a ′ k ns STARUNIA tvy Solo Bystrytsya ° SAMBIR OE-L 48 42 N GV-200 UNIT am Place of discovery tre MARKOVA GV-B eS of woolly rhinoceroses inn a 410 R and mammoth k Mo-4 P-3 v a y E-3 n a M Ma-10 BORYSLAV- GVIZD POKUTTYA Lukavets lyky N Ve Ve UNIT P-0 N - 1 lyky S K ′″ Luk ′ IB A avet ka 420 U ° ° nyans sRive NIT BYTKIV vir 1 48 41 10 48 38 Nad NADVIRNA E- 0 24km Near-surface geochemical r PNIV 0 100 200 m measurement line Bystrytsya 24°29′″ 10 E 24° 29′″ 30 Figure 1. Location map of study area. Photo of unique woolly rhinoceros in Natural History Museum in Kraków by W.J. Mo´scicki. 2.0 A 20 B “Upper oil eye” C 1.8 1.6 8 3 –25 1.4 10 ) MIXING 1.2 MICROBIAL NII 10 METHANE (‰ ROGE II 2 MICROBIAL 1.0 2 KE THERMOGENIC H (‰) ) N MICROBIALGASES 26 –30 METHANE 10 0 GASES E r G MIXING III 0.8 R(%) C (C C (CO ) “Lower oil eye” Gases: 13 13 –10 Near-surface 0.6 KERO δ 1 MIGRATION δ C4263 10 –35 H KEROGEN NG Surface seep OXIDAT I C CH = /(C H +C H ) THERMOGENIC IO MIX Deep accumulation N GASES –20 MIGRATION –70 –60 –50 –40 –30 –70 –60 –50 –40 –30 –70 –60 –50 –40 –30 δ13 δ13 δ13 C(CH4 ) (‰) C(CH4 ) (‰) C(CH4 ) (‰) δ13 Figure 2. Genetic characterization of natural subsurface and near-surface gases using (A) hydrocarbon index (CHC), (B) C(CO2), and δ13 δ13 (C) C(C2H6) versus C(CH4). Compositional fi elds in A are after Whiticar (1994), and compositional fi elds in B are after Kotarba and Rice (2001) modifi ed by Kotarba. Positions of vitrinite refl ectance curves for type II kerogen in C are after Berner and Faber (1996) and have been shifted based on average of δ13C values of Oligocene Menilite Formation type II kerogen (25.2‰) after Kotarba et al.