• Volume 87,Issue 8,2013 Table of Contents
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    • NEW DISCOVERY OF INVERTEBRATE ZOOLITE AND STRATIGRAPHIC SUBDIVISION AND COR-

      2013, 87(8):1049-1058.

      Abstract (1085) HTML (12) PDF 5.68 M (1766) Comment (0) Favorites

      Abstract:The red strata of a suite of bearing-dinosaur egg fossils are exposed in Xiaguan-Gaoqiu Basin of Henan Province. It has been called the Gaogou Formation, the Majiacun Formation, the Sangping Formation and the Xiaguan Formation, and the formal stratigraphic section has not surveied formerly. Because the invertebrate and plant fossils that can be used to can determined stratigraphic epoch have not discovered except the dinosaur and dinosaur egg fossils, so a monograph not yet came out. In recent years, the authers have surveied the systematic stratigraphic section and found the a abundent invertebrate and plant fossils in 2011 except new discovery of dinosaur fossil Baotianmansaurus. So, the establishment of the stratigraphic unit of the formation level and stratigraphic subdivision and correlation have already basic condition. This discovery indicates the Xiaguan Formation may be the early-middle Late Cretaceous in age, and most possibly the early-middle Turonian to the middle Campanian.

    • Early Cretaceous petrified woods and sedimentary environment from Yingen-Ejinaqi Basin, Inner Mongolia

      2013, 87(8):1059-1066.

      Abstract (1164) HTML (12) PDF 3.53 M (1551) Comment (0) Favorites

      Abstract:Yingen-Ejinaqi Basin is a Mesozoic-Cenozoic intermountain petroliferous basin in the Inner Mongolia, northern China, which was largely filled by the Cretaceous alluvial-fluvial-lacustrine clastic sediments interbedded with volcanic layers. Two sites of well-preserved petrified woods were discovered from the Lower Cretaceous Bayingebi Formation and Suhongtu Formation in the southeastern Basin. In this paper we described the taphonomic characteristics and morphological structures of petrified woods. And discussed the climatic environment when they buried in terms based on the palynologic datas. In addition, palynological samples are collected from the upper Bayingebi Formtion and lower Suhongtu Formtion. The palynological study suggests a late Early Cretaceous age, and also reflects a wet and warm climate in this area. According to the lithological characters, the first locality of the fossil woods are rapidly buried by intermittent floods, debris flows deposits. And the second ones are suddenly covered by pyroclastic deposits which possibly occurred at the late Early Cretaceous period on the basis of published dates.

    • A preliminary research on the discovery of slump structures in Cambrian system in the Western Hills of Beijing

      2013, 87(8):1067-1075.

      Abstract (1159) HTML (11) PDF 7.99 M (1919) Comment (0) Favorites

      Abstract:The Cambrian system in the Western Hills of Beijing is outcropped mainly along the Yongding river valley in the north and along the Dazhihe river valley in the south. Famed for the complete sequence, unique rock types and good exposure, the Western Hills in Beijing has been a key location for the study of Cambrian system in China. However, nearly all the field work and publications have been concentrated on the northern part (along the Yongding river valley), for the convenient transportation. The slump structures are found about 5 m above the boundary between the Zhangxia Formation (Middle Cambrian oolite) and the Gushan Formation (Upper Cambrian) in the southern part of Wetsten Hillsalong a branch of the Dazhihe river valley). The slump is mainly composed of micro folds and faults. Axial planes of these folds are SN-striking. The typically dip gently towards the east. The average dipping angle of the micro-faults is about 10 degrees. The deformation pattern is very similar with that in the Late Pleistocene Lisan Formation near the Dead Sea. Two wedge-shaped features are discovered just below the slump layer. Our preliminary research shows that the direct trigger for the newly discovered slump structures are probably the palaeoearthquake associated with the tilting movement of the North China palaeoplate in the late Cambrian.

    • Erosion thickness of the main unconformities of Dangyang Subbasin, Jianghan Basin: constrained by the Middle-Low thermochronology

      2013, 87(8):1076-1088.

      Abstract (1060) HTML (12) PDF 28.30 M (1234) Comment (0) Favorites

      Abstract:Middle-Low thermochronological data, including apatite fission track, (U-Th-Sm)/He and vitrinite reflectance, were used to analyze the erosion thickness occurring at the two main unconformities. Results shows that, the accumulated erosion thickness at the unconformity T1, developed during late Paleogene, is more than 1000m, and in some tectonic inverse area such as Xiejiawan fault-fold belt, erosion thickness might be larger than 2000m. While the accumulated erosion thickness at the other main unconformity T11, which developed during Late Jurassic through Early Cretaceous, is larger than 4000m, most of which was eroded during the Late Jurassic through Early Cretaceous tectonic event, indicating that the eroded thickness during this period is much larger than that of the unconformity T1 happened at the end of Paleogene. During Late Triassic through Jurassic, the studied area developed foreland basin with a wedge Jurassic strata obviously thicker in the eastern region. The Jurassic sediment thickness in the eastern foredeep was larger than 5000m. The pre-Cretaceous formation in the Triassic and Jurassic outcrop area and some local fault-fold belts in Jiangling sag obtained its deepest depth and highest temperature, thus its Ro% during the Jurassic foreland basin, was buried; The original rifted basin developed during Late Cretaceous through Paleogene was much larger than nowadays residual basin, the thickness of the upper Cretaceous-Paleogene was larger than 9000m, in which the Paleogene might be thicker than 7000m, and the Paleogene in Xiejiawan fault-fold belt of Herong sag might be larger than 3300m.

    • Geochronology and geochemistry of the Gerizhuotuo diorites from the Buqingshan tectonic mélange belt and their geologic implications

      2013, 87(8):1089-1103.

      Abstract (1259) HTML (11) PDF 4.12 M (2020) Comment (0) Favorites

      Abstract:The zircons have high ratio of Th/U (0.63-1.28) and are magma originated for their internal oscillatory zoning on CL imagines of the Gerizhuotuo diorites in the Buqingshan tectonic mélange belt, and LA-ICP-MS zircon geochronological age of 225.8±1.5Ma (MSWD=0.53), implying intruding at the early period of Late Triassic. Geochemically, the rocks have middle contents of SiO2, e.g. 53.07% - 58.74%, and relatively high Al2O3 (14.66% - 16.17%), low alkaline (4.76% - 6.04%) ,high K2O(1.60%~2.90%)and Rittmann index σ from 1.69 to 2.66, belongs to the high-K calc-alkaline series. The average value of ΣREE is 158.36×10-6 ~211.50×10-6,δEu= 0.85 – 0.97. The chondrite normalized REE pattern curve is right-sloping type,and the rocks possess weak negative Eu anomalies. The primitive mantle standardized trace elements are characterized that HFSE(Nb, Ta, P,etc. ) and LILE(Ba、Sr,Ti,etc. ) has remarkable negative anomalies,Rb,U,La,Hf,Nd,etc. ) has remarkable positive anomalies. Gerizhuotuo diorite is formed in the high temperature environment (800 ° C ±), with post-collisional magmatism characteristics, is the product of crustal partial melting after the collision of the the East Kunlun block and Bayan Har block.

    • Petrological and Mineralogical Characteristics of Explosion Breccia in Bachu, Xinjiang and its constraints on the magmatic processes

      2013, 87(8):1104-1123.

      Abstract (1215) HTML (12) PDF 20.76 M (1375) Comment (0) Favorites

      Abstract:Systematic studies on the main mineralogy of the diatreme breccias in the Bachu, Xinjiang, the results show that the rocks consist of two parts: xenoliths of ultramafic rock and cements. In the cements, the chiefly minerals are clinopyroxene, olivine, plagioclase and amphibole. They are both from the crystallization of the Kimberlitic magma and the xenocrysts which are the same source of the xenoliths of ultramafic rock. In the cements, the latter phenocrysts have higher Mg# than the previous phenocrysts and Clinopyroxene and amphibole develop the reverse zoning, which indicating that the magma has sufferd the magma mixing during its evolution. This study also shows that there are many mineralogy differences between the xenoliths of ultramafic rock and the Wajilitage layered complex, so we can say that they are no causal relationship between the two. On the craton age, the thickness of the lithosphere, rocks exposed position and the depth of the magma source, the Bachu kimberlite is different from the kimberlite of the eastern China, which constitutes a negative factor for the deposit.

    • Pb isotope Constraining Ore–forming Source Origin of the Dexing Copper Deposit

      2013, 87(8):1124-1135.

      Abstract (1296) HTML (11) PDF 6.51 M (1818) Comment (0) Favorites

      Abstract:The Dexing porphyry copper deposit, Jiangxi Province, is the largest porphyry copper deposit in China, and there have been some controversies on the ore–forming source of this deposit. This study has carried out the Pb isotope analyses of pyrites from the Tongchang and Fujiawu mine. The results show that the two mines have the consistent Pb isotopes, with 206Pb/204Pb ratios ranging from 17.954 to 18.320 (with a mean of 18.097), 207Pb/204Pb ratios ranging from 15.407 to 15.517 (with a mean of 15.476), and 208Pb/204Pb ratios ranging from 37.888 to 38.153 (with a mean of 37.999), respectively. The Pb and previous S isotope features indicate that the ore–forming sources are mainly derived from the upper mantle, other than the Neo–proterozoic meta–sedimentary rocks of Shuangqiaoshan Group. On the basis of comparisons of more than twenty molybdenum–bearing deposits worldwide with porphyry type, skarn type and quartz–vein type, we further attribute the high Re–187Os contents of the molybdenites to a mantle origin. The large scale copper deposit should be emplaced in a continental arc setting coupled with westward subduction of the palaeo–Pacific plate, and formed by the Fe3+–rich fluids/magmas released by the P–MORB interacting with the lithospheric mantle wedge.

    • The sedimentary micro-facies of the Lower Cambrian Qiongzhusi formation in southern Sichuan Basin

      2013, 87(8):1136-1148.

      Abstract (1133) HTML (13) PDF 5.43 M (1555) Comment (0) Favorites

      Abstract:Shale gas is one of the most important and realistic unconventional gas resources in the future of China. Strengthening the basic research in such research field has large significance to the theoretical innovation in shale gas hydrocarbon accumulation and the use of Shale gas mining technology and accurate calculation of resources. Therefore, the article took the use of large numbers of first-hand information, such as field outcrops data, drilling cores and logging data, organic geochemical analysis and test results for shales, made a detailed analysis for the characteristic of shale sedimentary micro-facies and gas baring of the Lower Cambrian Qiongzhusi formation in southern Sichuan Basin. Combining the sedimentary facies signs and logging phase, it has clearly pointed out that the muddy deep-water shelf micro-facies is the favorable sedimentary micro-facies for the Quality shaleof Lower Cambrian Qiongzhusi formation in the southern Sichuan basin.

    • Characters of Two-Component Constitution of Deep-water Deposit And Sequence Stratigraphy Divided In Niger Delta Basin

      2013, 87(8):1149-1157.

      Abstract (1076) HTML (11) PDF 4.74 M (1402) Comment (0) Favorites

      Abstract:Base on bore logs and seismic facies characters,the article establishs five criterias for judging sequence boundary of deep-water setting, and then the strata of middle-upper Miocene are divided into six third-order sequences, two second-order sequences in Nigeria deep-water setting areas. Base on two-component Constitution feature of deep-water depositional cycle, deltas and relative sea-level change in shelf area, Classic threefold division of systems tracts are classified as twofold division of systems tracts: allogenetic systems tract and autogenetic systems tract. Allogenetic systems tract starts from base level descending to early stage of transgression, and it mainly has gravity current deposits that are composed of mass transport deposits and turbidite fans. Autogenetic systems tract starts from middle-late stage of transgression to base level rising to the highest position, it mainly deposits pelagic and hemipelagic argillaceous sediments.And we also analysis controlled factors of sequence stratigraphy development, but due to the limited datum, it is difficult to predicate that one or even more factors determine sequence development for most sequences.

    • Characterization of REE geochemistry of Permian coals from Zhuji Coal Mine, Huainan Coalfield and its geological implication

      2013, 87(8):1158-1166.

      Abstract (1185) HTML (12) PDF 3.62 M (1488) Comment (0) Favorites

      Abstract:The concentrations of the rare earth elements (REEs) in 371 Permian coal samples taken from 11 coal seams of three depositional formations in Zhuji Coal Mine, Huainan Coalfield were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The geochemical characteristics of REEs in coal were discussed and its geological implication was investigated. The total concentration of REEs ranges from 86×10-6 to 143×10-6 with an average value of 112×10-6. On average, the REEs concentrations in coals of Upper and Lower Shihezi Formations are higher than Shanxi Formation by 38% and 25%, respectively, which is suggested to relate the difference of respective depositional environment. Coals in three formations show similar REEs distribution, and are characterized by enrichment of light REEs and depletion of heavy REEs. The distribution of light REEs is steep and heavy REEs is rather flat. Moderate Eu negative anomaly (an average of 0.59 for δ Eu in range of 0.52 ~ 0.80) and absence of Ce anomaly (an average value for δ Ce is 0.99 in range of 0.93 ~ 1.04) were observed for all the samples, which suggests weak influence of seawater on terrestrial detritals-dominated coal-forming swamp. Positive but insignificant correlation (R=0.59) of REEs vs. ash yields was seen in bivariate plot, demonstrating co-existence of inorganic and organic affinities for REEs. The XRD mineral analysis and petrographic observation show that REEs were possibly incorporated into the inorganic clays such as kaolinite. In addition, cluster analysis shows that REEs were grouped together with terrigenous elements such as Si, Al, Ti, Ni, Sc and Se rather than marine elements (B, Sr and Ca).

    • Gas geochemical features and their indicative significance in DK-8 gas hydrate drilling hole of the Qilian Mountain permafrost

      2013, 87(8):1167-1178.

      Abstract (1252) HTML (11) PDF 22.66 M (1414) Comment (0) Favorites

      Abstract:After gas component and methane carbon isotope were analyzed from cores at different depths in DK-8 gas hydrate drilling hole in the Muli permafrost of the Qilian Mountain, their features changing with depth were correlated with intervals of gas hydrate & anomalies, and with spatial distribution of faults or fractures; their indicative significance was finally pointed out to gas hydrate occurrence and hydrocarbon migration. Gas contents (µl/kg) in cores behave their heights at intervals of 149~167m, 228~299m, 321~338m and 360~380m, which were basically consistent with intervals of gas hydrate and its anomalies, suggesting that high values of gas content were caused by gas hydrate and its anomalies. Total volumetric percentage of hydrocarbon gases in core (vol%), carbon isotope of methane (δ13C1, ‰PDB), and ratios of C1/ƩC1-5, C1/ΣC2-5, C1/ΣC2-3, C1/C2, C2/C3, C2/ΣC3-4, iC4/nC4 and iC5/nC5 from samples with different distance away from faults or fractures, indicated that hydrocarbon gases in cores with high value features which represent gas hydrate and its anomalies, were mainly migrated from deep sources and were closely related with faults or fractures; deeper faults or fractures may serve as migration paths for hydrocarbon gases, and middle to shallower faults or fractures may provide accumulation space for gas hydrate.

    • Variation and mechanism of paleoclimate in the Last Glaciation in the tropic northern Leizhou Peninsula in South China

      2013, 87(8):1179-1192.

      Abstract (1168) HTML (12) PDF 18.23 M (1110) Comment (0) Favorites

      Abstract:Based on the analyses of bulk organic δ13C for the Wushan and the Xialu peat cores, as well as a fluvial or swamp composed sequence, the Quanshui section, from the north of Leizhou Peninsula, we reconstructed the history of climate changes between 48.0 and 10 cal ka BP in the north tropic region in South China. On basis of comparison with the multi-proxy climatic records such as the loss on ignition (LOI), the content of organic matter (OM), the degree of humification (HD), and the Low field magnetic susceptibility (χlf) of three profiles, we interpret that more negative bulk organic δ13C values would suggest wetter and warmer conditions, implying a strengthening of the East Asian (EA) summer monsoon, whereas less negative δ13C values indicate drier and cooler conditions, suggesting a weakening of the EA summer monsoon. A warm and wet period occurred between 48.0 and 28 cal ka BP. A climate shift occurred at 22 (or 20) cal ka BP, and the driest and coldest period occurred between 18.0 and 16.0 cal ka BP ,which indicate a weak EA summer monsoon and may be related to the last glacial maximum (LGM). After 12.0 cal ka BP, the climate changed towards wetter and warmer conditions. From 48.0 to 10.0 cal ka BP, several short positive δ13Corg excursions indicate the expansion of C4 plants or the C3 plants characterized by more positive δ13Corg value. These excursions shows a similarity with the Heinrich events and other cold millennial-scale oscillations evidenced from a Greenland ice core and the Chinese stalagmite record. We also demonstrate that the variations of climate reflected by bulk δ13Corg records show an inverse correlation with the South American monsoon in the South Hemisphere. We deduce that the solar radiation, as well as the solar radiation-driven the shift of the intertropical convergence zone (ITCZ), may have played a role in the climate changes in the Last Glaciation in north tropic China. The migration of ITCZ may have caused meridional asymmetry in the Hadley circulation, and would change meridional moisture transport. This will make the climate changes in northern low latitudes show an inverse correlation with southern low latitudes. Besides, high latitudes of the southern hemisphere may play a key role in the climate changes of Leizhou Peninsula through the mechanism of “push” or “pull”.

Established in 1922, Monthly

Editor in Chief :YANG Jingsui

Governing body:China Association for Science and Technology

Organizer:Geological Society of China

ISSN:1000-9515

CN: 11-2001/P

Domestic postal code:2-113

Foreign issue code:M 78

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