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In contrast to Solnhofen-type conservation Lagerstätten, the platy limestones of the Benkovac Stone of the Eocene of Croatia contains a variety of trace fossils. They belong to the Nereites ichnofacies, characterized by a suite of highly specialized ichnogenera, turbiditic preservation, and distinctive pre-event versus post-event communities. In siliciclastic rocks, this ichnofacies stands for turbiditic deep-sea sediments. Also unusual is the lack of body fossils. The only exceptions are occasional plant debris and Bencovacina concentrica. n. gen., n. sp., which is affiliated with xenophyophorian Foraminifera. These giant protozoans survive on present deep-sea bottoms, but they were also common on the shallow-marine biomats in Ediacaran times. These findings contradict the current shallow-marine interpretation, which is based on the regional geologic setting and sedimentary structures typical for tempestites. Thus, the Benkovac Stone would be an ideal place to test the reliability of ichnological versus sedimentological depth criteria in an entirely calcareous sequence. 相似文献
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H. Paulick C. Ewen H. Blanchard L. Zöller 《International Journal of Earth Sciences》2009,98(8):1879-1899
The Rodderberg volcanic complex (RVC) is located within the city limits of Bonn (Germany) approximately 20 km to the north
of the Quaternary East Eifel Volcanic Field (EEVF). It is the product of intense phreatomagmatic volcanism forming a 90 m
deep maar crater and strombolian eruptions. Deposit features indicate that the location of the vent(s) shifted from N to S
during the strombolian phase. The erupted leucite-nephelinite magma (on the order of ca. 1 × 10−2 km3) was largely homogenous with minor, stratigraphically controlled, variation in olivine and clinopyroxene microphenocryst
content. Stratigraphic evidence and thermoluminescence dating indicate that the RVC erupted during the glacial MIS 8 at around
300 ka. During this time, the EEVF experienced a transitional stage between two major phases of volcanic activity involving
a change in magma sources. This is consistent with the RVC geochemical data which show affinities to both the older EEVF leucite-nephelinite
association (430–380 ka) and the younger basanite association (<215 ka). In the Eifel, magma ascent through the upper crust
is apparently linked to tectonic fractures. It may be speculated that a tectonically controlled diking event channeled magma
to the north of the main EEVF and that the RVC represents an exceptional surficial expression of a significantly larger subsurface
intrusion. This scenario would be consistent with recent observations of diking-related volcanism in the East African Rift
zone and previously inferred models for magma ascent in similar intraplate volcanic fields. 相似文献
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Lepisosteid fishes are well known from the Upper Cretaceous of Europe, but only by fragmentary remains from some Cenomanian and Campanian–Maastrichtian deposits. Here we report various cranial and postcranial remains of gars, discovered in the Upper Cretaceous (Santonian) Csehbánya Formation of Iharkút (Bakony Mountains, Hungary). These remains represent one of the most diverse assemblages of lepisosteid fish material from Upper Cretaceous continental deposits of Europe. Based on tooth morphology, scale-microstructure and the features of the supracleithrum we refer these remains to the genus Atractosteus. Besides some uncertain remains from the Cenomanian of France and Spain, the Santonian aged fossils from Iharkút represent the oldest undisputable occurrence of the family Lepisosteidae in the European continental Cretaceous. Using tooth crown morphology, the surface microstructure of the ganoid scales and the anatomy of the supracleithrum a review of the Late Cretaceous lepisosteid record suggests the occurrence of both Atractosteus and Lepisosteus in the European archipelago. 相似文献
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Yakovenchuk Victor N. Pakhomovsky Yakov A. Konopleva Nataliya G. Panikorovskii Taras L. Bazai Ayya Mikhailova Julia A. Bocharov Vladimir N. Ivanyuk Gregory Yu. Krivovichev Sergey V. 《Mineralogy and Petrology》2018,112(4):591-601
Mineralogy and Petrology - Batagayite, CaZn2(Zn,Cu)6(PO4)4(PO3OH)3·12H2O, is a new secondary phosphate mineral from the Këster deposit, Arga-Ynnykh-Khai massif, NE Yakutia, Russia. It is... 相似文献
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I. V. Pekov E. V. Sereda V. O. Yapaskurt Yu. S. Polekhovsky S. N. Britvin N. V. Chukanov 《Geology of Ore Deposits》2013,55(8):637-647
Ferrovalleriite, ideally 2(Fe,Cu)S · 1.5Fe(OH)2, a layered hydroxide-sulfide of the valleriite group and an analog of valleriite with Fe instead of Mg in the hydroxide block, has been approved by the IMA Commission on New Minerals, Nomenclature and Classification as a valid mineral species. It was found in the Oktyabr’sky Mine, Noril’sk, Krasnoyarsk krai, Siberia, Russia. Ferrovalleriite occurs in cavities of massive sulfide ore mainly consisting of cubanite and mooihoekite. In different cases, it is associated with magnetite, Fe-rich chlorite-like phyllosilicate, ferrotochilinite, hibbingite, or rhodochrosite. Ferrovalleriite forms crystals flattened on [001] (from scaly to tabular; up to 5 mm across and up to 0.3 mm thick), typically split and curved. Occasionally, they are combined into aggregates up to 1.5 × 2 cm. Ferrovalleriite is dark bronze-colored, with a metallic luster and black streak. The Mohs’ hardness is ca. 1; VHN is 35 kg/mm2. Cleavage is perfect parallel to {001}, mica-like. Individuals are flexible and inelastic. D(calc) = 3.72 g/cm3. In reflected light, ferrovalleriite is pleochroic from yellowish to gray; bireflectance is moderate. Anisotropy is strong, with bluish gray to yellowish beige rotation colors. Reflectance values [R 1–R 2 %, (λ, nm)] are: 15.6–16.6 (470), 14.8–20.5 (546), 14.7–22.3 (589), 14.5–24.1 (650). The IR spectrum shows the presence of (OH) groups bonded with Fe cations and the absence of H2O molecules. The chemical composition of the holotype (wt %; electron microprobe, H content is calculated) is as follows: 0.10 Al, 0.03 Mn, 45.31 Fe, 0.07 Ni, 18.29 Cu, 20.37 S, 15.62 O, 0.98 H, total is 100.77. The empirical formula calculated on the basis of 2 S atoms is: Al0.01Fe2.55Cu0.91S2(OH)3.07 = (Fe1.09Cu0.91)Σ2S2 · (Fe 1.34 2+ Fe 0.12 3+ Al0.01)Σ1.47(OH)3.07. The structure of ferrovalleriite is incommensurate (misfit); two sublattices are present: (1) sulfide sublattice, space group $R\bar 3m$ , R3m or R32; the unit-cell dimensions are: a = 3.792(2), c = 34.06(3) Å, V = 424(1) Å3 and (2) hydroxide sublattice, space group $P\bar 3m1$ , P3m1 or P321; the unit-cell dimensions: a = 3.202(3), c = 11.35(2)Å, V = 100.8(3) Å3. Together with this main polytype modification with three-layer (R-cell, Z = 3) sulfide block, the holotype ferrovalleriite contains the modification with one-layer (P-cell, Z = 1) sulfide block (sulfide sublattice with $P\bar 3m1$ , P3m1 or P321, unit cell dimensions: a = 3.789(4), c = 11.35(1) Å, V = 141(5) Å3). The strongest reflections in the X-ray powder pattern (d, Å-I) are: 5.69–100; 3.268–58; 3.163–36; 1.894–34; 1.871–45. 相似文献
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The amino-acid compositions of limestones whose origin is thought to be related to the activity of Cyanophyceae have been studied to determine whether the characteristic components of these organisms would be present as geochemical fossils. A significant amount of amino acids is present and the content can be divided between a “free amino-acid fraction” and a “combined amino-acid fraction” containing different amounts of acidic and basic amino acids. There is evidence to suggest that the amino acids and amino sugars isolated are indeed contemporaneous with the formation of the sediments. The absence of diaminopimelic acid and the very small amount of muramic acid present shows that these two important components of algal and bacterial cell-membranes have apparently been extensively degraded. 相似文献
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20 0 2年6月～7月间,十几位中外古生物学者在辽宁省北票市上园镇燕子沟附近中生界义县组底部地层中,发掘出了两具恐龙头骨化石。经研究确定,属于一种新发现的原始角龙类恐龙。研究者为中国科学院古脊椎动物和古人类研究所的徐星、汪筱林、尤海鲁、美国原野博物馆的PeterJ .Makovicky和美国自然历史博物馆的MarkA .Norell ,将这种新发现的小型恐龙命名为“燕子沟辽宁角龙”。角龙类恐龙是恐龙演化历程中最后的和最多样化的代表之一,以植物为食,通常分为两大类:长有颈盾的新角龙类和具有与鹦鹉相似喙部的鹦鹉嘴龙类,它们之间的系统演化关系… 相似文献
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Prokopyev Ilya R. Doroshkevich Anna G. Redina Anna A. Obukhov Andrey V. 《Mineralogy and Petrology》2018,112(2):257-266
Mineralogy and Petrology - The Ust-Chulman apatite ore body is situated within the Nimnyrskaya apatite zone at the Aldan shield in Russia. The latest data confirm the carbonatitic origin of the... 相似文献
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W. David SINCLAIR 《地质学报》2014,88(Z2):463-465
Please refer to the attachment(s) for more details. 相似文献
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JI Shu''an GAO Chunling LIU Jinyuan MENG Qingjin JI Qiang Institute of Geology Chinese Academy of Geological Sciences Beijing Dalian Natural History Museum Dalian Liaoning 《《地质学报》英文版》2007,81(2)
An incomplete specimen of Sinosauropteryx prima collected from the Early Cretaceous Yixian Formation of the Dawangzhangzi area in Lingyuan, western Liaoning is depicted. It represents the first systematically described material of this feathered compsognathid outside the Sihetun area in Beipiao. This specimen shows some diagnostic features of Sinosauropteryx prima, such as the very short forelimb in relation to hindlimb with the length ratio of humerus plus radius to femur plus tibia just around 30%, and the long and massive first manual ungual subequal in length to radius. The presence of Sinosauropteryx prima only at Sihetun and Dawangzhangzi supports the suggestion that the fossil-bearing beds in the Sihetun and Dawangzhangzi areas are equivalent to each other within the Yixian Formation. 相似文献
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环境地球物理学:新概念(英文) 总被引：3，自引：0，他引：3
Gueli S.Vakhromeev 《地学前缘》2001,8(1):47-57
环境地球物理学是勘探地球物理学新科学和新应用分支。环境地球物理定义为用仪器对以各种物理场形式出现的物质和能量进行测量进而对环境进行多重目的监控。环境地球物理再细分为灾害、防护及医学环境地球物理。对环境物理异常及其天然和人工源进行了整理、分类。文中说明了地质生态目标和过程的静态和动态物理地质模型系统 ,以及多元建模原则。环境地球物理场的变化可作为地质环境演变部分或全部丧失其稳定性乃至被破坏的明显标志 ,且意义重大。灾害事件 (地震、滑坡、海震等 )的预报被证明是可能的。这些灾祸是各种技术因素或触发地质过程的结果 ,它们发展潜隐而发生突然 ,正如缓发生态地质炸弹一样。 相似文献
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Based on the concepts (a) that the stable C and O isotopes combined with the Sr isotope ratios of fracture fills should reflect the source groundwater from which the solid phases precipitated and (b) that U-series disequilibria (USD) enable the calculation of residence time for the U by using Fe oxides as the best candidate, an “isotopic toolbox” was applied to fracture fill from the crystalline basement of the Vienne district. The fracture fills are formed mainly of carbonates, clays and Fe oxides. The isotope data indicate two main generations of carbonate that originated from hydrothermal circulation and equilibrium with present-day groundwaters but the Sr isotope ratios highlight another component with a higher 87Sr/86Sr ratio reflecting the complexity of the water–rock interactions.For the USD, the Fe-hydroxides located at 207 m depth yield an age of 102 ± 5 ka (St. Germain I interglacial stage), whereas those located at 277 m and 300 m yield respective ages of 173 ± 15 ka and 181 ± 10 ka. These corresponding to the transition between the penultimate glacial period (isotopic stage 6) and the end of the preceding interglacial stage (isotopic sub-stage 7a). Investigating water–rock interaction (87Sr/86Sr, 18O, 13C, USD) in the fracture-fill minerals from the crystalline basement has shown that such an approach is relevant to developing an understanding of how the groundwater system has changed over time. 相似文献
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Yakovenchuk V. N. Pakhomovsky Ya. A. Konoplyova N. G. Panikorovskii T. L. Mikhailova Yu. A. Bocharov V. N. Krivovichev S. V. Ivanyuk G. Yu. 《Geology of Ore Deposits》2018,60(7):587-593
Geology of Ore Deposits - Epifanovite, NaCaCu5(PO4)4[AsO2(OH)2] · 7H2O, a new natural copper, sodium and calcium arsenate–phosphate, has been found in a quartz–phosphate pocket... 相似文献
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Eclogite–gneiss complex of the Muya block (East Siberia): age,mineralogy, geochemistry,and petrology
V.S. Shatsky E.S. Sitnikova A.A. Tomilenko A.L. Ragozin O.A. Koz’menko E. Jagoutz 《Russian Geology and Geophysics》2012,53(6):501-521
Results of study of eclogite–gneiss complex of the Muya Block (East Siberia) are presented. Several structural types of the studied eclogites have been recognized. Kyanitic eclogite has been found for the first time. The host granite-gneisses are two-mica and biotite varieties, mainly garnet-bearing. The exposure of eclogites from different depths of the subducted plate at the present-day denudation level might be the reason for the wide range of the equilibrium temperatures of the Muya block eclogites (590–740 °C). The Sm–Nd dating of the eclogites and host gneisses showed the Neoproterozoic age of high-pressure metamorphism (～630 Ma). The model age (TDM) of the eclogites (720 Ma) differs considerably from the model age of the host gneisses (>1.3 Ga). The geochemical features of the eclogites point to the mobility of LILE (Rb, Cs, Ba, K) and LREE during their interaction with fluids, whereas the gneisses in the same process showed the mobility of LILE only. The oxygen isotope composition of minerals in the eclogites varies over a narrow range (δ18O = 5.5–3.9) and is close to the average mantle value, which evidences a negligible interaction between the eclogite protoliths and meteoric or sea water. The study of fluid inclusions in quartz from the eclogites and host gneisses showed a predominance of liquid-nitrogen inclusions in the former and carbon dioxide inclusions in the latter. 相似文献