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Paleomagnetic study on the Early Triassic red beds from Jiaocheng, Shanxi Province ——Local rotation and tectonic significance

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Science China Earth Sciences 2004年第2期47卷 108-114页

作者： SHI Ruiping HUANG Baochun ZHU Rixiang REN Shoumai institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029China

Paleomagnetic and rock magnetic study has been conducted on the Early Triassicred beds of Liujiagou Formation from Jiaocheng, Shanxi Province. Hematite was shown as themain magnetic mineral. After eradicating an initial viscous component at room temperature to～100℃-200℃, thermal demagnetization shows that most samples contain two remanencecomponents, intermediate-temperature remanence component at 250℃-500℃ and high-tem-perature component at 500℃-680℃. The intermediate-temperature component has a negativefold test at the 95% confidence level. And the pole position of the intermediate-temperaturecomponent in geographic coordinates is correlated with the Middle Jurassic reference pole of theNorth China Block (NCB) within the 95% confidence, suggesting that it might be a remagnetiza-tion component acquired during the Yanshanian period. The high-temperature component con-tains both reversal and normal polarities with positive fold test and C-level positive reversal test atthe 95% confidence level, which suggests that this high-temperature component can be regardedas primary magnetization. Comparison of this newly obtained Early Triassic paleopole with thecoeval mean pole of the Ordos Basin suggests that a locally relative rotation may have happenedbetween the Ordos and the Jiaocheng area of Shanxi Province. This rotation may be related withtwo faults: one is Lishi big fault separating Ordos from Shanxi and the other is Jiaocheng big fault,which is situated in the southeast of sampling locality and was still in motion during the Cenozoic.

关键词： Jiaocheng, Shanxi, paleomagnetism, Early Triassic, local rotation.

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Paleo and Modern Stress Regimes of Central North Tabriz Fault, Eastern Azerbaijan Province, NW Iran

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Journal of Earth Science 2015年第3期26卷 361-372页

作者： A Yousefi-Bavil M Moayyed Department of Geotectonics and Regional geology Geology Institute of Azerbaijan Department of Earth Sciences University of Tabriz

The North Tabriz fault is a segmented dextral fault in Northwest Iran, with a history of major destructive earthquakes that have repeatedly destroyed the city of Tabriz（current population 1.6 million）. The quiescence of the fault（last major temblor in 1854） and a lack of outcrop study have hampered stress analysis. Resolution of the stress states on the fault could be used for seismotectonic study along the North Tabriz fault and for understanding the geodynamics of the Arabia-Eurasia collision zone. Using fault-slip data collected from 88 localities in the fault system, we conducted an inversion analysis of this fault-slip data and analysis of the stratigraphic, geometric, and structural information. As a result, we confirmed that transcurrent deformation is prevalent on the North Tabriz fault and adjacent areas and is generally accomplished by predominant NW-SE-trending dextral and NE-SW-trending sinistral faults. Specifically, three separate tectonic episodes are recognised from the stress inversion data, consistent with the geologic data：（i） a post-Cretaceous and pre-Early Miocene compressional（Laramian） stress regime,（ii） an Early Miocene extensional stress regime, and（iii） modern tectonic episode with different local stress regimes（compressional and extensional） along the different segments of this fault.

关键词： stress regime NW Iran tectonics North Tabriz fault stress inversion strike-slip fault

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Suitability assessment of deep groundwater for drinking, irrigation and industrial purposes in Jiaozuo City, Henan Province, north China

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Chinese Science Bulletin 2013年第25期58卷 3098-3110页

作者： SHI JianSheng MA Rong LIU JiChao ZHANG YiLong institute of Hydrogeology and Environmental geology

Groundwater has been a major natural resource for human consumption in north China. It is necessary to appreciate the suitability of deep groundwater for drinking, agricultural irrigation, and industrial uses in this region. To this end, a total of 47 groundwater samples were collected from the study area; by comparing the concentrations of different hydrochemical variables with quality standard values, the variable fuzzy set (VFS) was applied to calculate the groundwater quality index (GQI) for various purposes, respectively. Afterward GQI spatial distribution maps were constructed using a geographic information system (GIS) tool to delineate spatial variations of groundwater quality. In this case study, the GQI spatial distribution maps reveal that the areas covered by "Maximum Permissible" groundwater for varying purposes (drinking, irrigation, and industrial) is 1377.2; 2354.7; and 3854.8 km2, respectively. The groundwater in the eastern part of the study area is suitable for drinking, with the southwestern region as the irrigation water source; the entire study area is acceptable for use in industrial, except the western part of Jiaozuo City. Therefore, the GQI spatial distribution maps can provide useful information for non-technical decision makers for better sustainable groundwater resources management.

关键词：工业用途农业灌溉中国北方水饮用焦作市适宜性评价河南省地下水水质

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Properties of soils in Grove Mountains,East Antarctica

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Science China Earth Sciences 2003年第7期46卷 683-693页

作者：李潇丽刘小汉琚宜太黄费新 institute of geology and Geophysics Chinese Academy of Sciences

Three cold desert soil sites were first found in the southern Mount Harding, Grove Mountains, East Antarctica. The soils are characteristics of the widespread occurrence of surface desert pavement, abundant water-soluble salts, strongly stained upper portion of soil profile, slightly acid and negligible organic matter content. A 1:5 soil-water extracts analysis indicates that the dominant cations are Mg2+ and Na+, followed by Ca2+ and K+, and the main anion is SO 4 2? , then Cl? and NO 3 2? . The accumulation of water-soluble salts indicates ion transportation in the frigid and arid Antarctica environment. The distribution of the salts is related to the maximum content of moisture and clay mineral. Clay fraction migration occurs in the soils, which is different from that of other cold desert soils. The upper horizons of some profiles are generally stained, namely rubification, primarily because of the weathering of iron-bearing minerals. The reddish hues of cold desert soils have been attributed to relatively high concentrations of dithionite-extractable Fe (Fed). The weathering features of soils suggest that the soil age of this area is 0.5–3.5 Ma. No remnants of glaciations were found on the soil sites of Mount Harding, which suggests that the Antarctic glaciations have not reached the soil sites since at least 0.5 Ma, even during the Last Glacial Maximum.

关键词： the Grove Mountains, cold desert soil, desert pavement, soluble salt, Fed.

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The Pre-Sturtian Negative δ^(13)C Excursion of the Dajiangbian Formation Deposited on the Western Margin of Cathaysia Block in South China

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Journal of Earth Science 2016年第2期27卷 225-232页

作者： Lianjun Feng Qirui Zhang Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences institute of geology and Geophysics Chinese Academy of Sciences

The Dajiangbian Formation in South China is a siliciclastic-dominated sedimentary succession with low-grade metamorphism deposited on the western margin of the Cathaysia Block, and is capped by a glaciogenic diamictite（the Sizhoushan Formation）. The Sizhoushan glaciogenic strata can be attributed to the Jiangkou glacial（Sturtian glacial） episode as they share stratigraphic and lithological similarities with Jiangkou strata in South China. Some carbonate, chert and shale units throughout the upper part of the Dajiangbian Formation were sampled for carbonate carbon isotope（δ^（13）C_（carb）） and organic carbon isotope（δ^（13）C_（org）） analyses. A range of geochemical indices including oxygen isotopes（δ^（18）O） and Mn/Sr（Fe/Sr） ratios suggest that primary carbon isotope values were preserved in the upper Dajiangbian Formation. The upper Dajiangbian Formation shows δ^（13）C_（carb） of-0.1‰, upward decreasing towards to-5.4‰. We suggest that the negative δ^（13）C excursion beneath the Sizhoushan diamictite is correlative with the Pre-Sturtian Islay δ^（13）C_（carb） anomaly and allows correlation with the global Neoproterozoic isotope stratigraphy. We find that carbonate and organic carbon isotope data of the upper Dajiangbian Formation are coupled, consistent with the δ^（13）C_（carb）-δ^（13）C_（org） pattern observed on multiple continents.

关键词： Neoproterozoic Cryogenian carbon isotopes Islay anomaly Cathaysia Block.

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Fenitized Wall Rock Geochemistry of the First Carbonatite Dyke at Bayan Obo, Inner Mongolia, China

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Acta Geologica Sinica(English Edition) 2018年第2期92卷 600-613页

作者： WANG Kaiyi ZHANG Jien YU Liangjun FANG Aimin DONG Ce HU Fuyou institute of geology and Geophysics Chinese Academy of Sciences

The first carbonatite dyke at Bayan Obo is well exposed on the surface for a length and width of approximately 60 m and 1.1-1.5 m, respectively. Along its strike, the fenitized H1 （Qs） and H2 （Cs） quartzite is replaced by Na-amphiboles, aegirines, and alkali-feldspars, intermittently stretching as far away as 800 m in length. Based on petrographical characteristics, the dyke＇s fenitized wall rocks are divisible into different zones：（1） outer, （2） middle, and （3） inner. The outer zone is 5-17 m from the NW margin of the dyke. The middle zone is located at 3.5-5 m from the NW margin of the dyke. The inner contact zone is located between direct contact with the dyke and 3.5 m from the dyke. In the outer zone, upon visual examination, no evidence of outcrop fenitization was found and the major elemental rock composition is nearly identical to the unaltered H1 and H2 lithologies. In the thin sections, however, small amounts of Na-amphibole and phlogopite are present. Despite relatively poor development throughout the 5 m of fenitization, the wall rocks have retained at least a small geochemical signature comparable to the original sedimentary protolith. The fenites occurring in the inner zone exhibit distinct variations, not only for the sharp contact at the outcrop scale, but also for variations in major, rare earth elements （REE）, and trace elements and Sm-Nd isotope composition. The wall rocks within 3.5 m have undergone strong fenitization, inheriting the geochemical signature derived from the carbonatite dyke. Fenitization in the middle zone was not as strong, at least compared to the inner zone, but was stronger than the outer zone. Compared to some trace elements and REEs, the major elements are relatively immobile during fenitization. The Sm-Nd isotope data for the carbonatite dyke and the adjacent fenitized wall rocks, where the Sm and Nd originate solely from the dyke, plots as a six-point isochron with an age of 1308~56 Ma. This age is identical to that of or

关键词： Bayan Obo first carbonatite dyke fenitization

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Morphogenic Uncertainties of the 2008 Wenchuan Earthquake: Generating or Reducing?

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Journal of Earth Science 2014年第4期25卷 668-675页

作者： Zhikun Ren Zhuqi Zhang Jinhui Yin Fuchu Dai Huiping Zhang State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration institute of geology and Geophysics Chinese Academy of Sciences

Landscape evolution in active orogen region is inevitably affected by landslides associated with strong earthquakes, rain or storm. However, quantitative studies of the orogenic or eroded volumes are rarely demonstrated. The 2008 Wenchuan Earthquake triggered serious landsliding, consequently, a large amount of landslide material. However, the landslide volume is estimated mainly on the landslides areas interpreted in their semi-automated landslide mapping algorithm. However, the total volume of landslides triggered by the Wenchuan Earthquake amounts to 5-10 times bigger than the expected upper bound according to the empirical correlation between ＂total landslide volume＂ and ＂moment magnitude＂. Here we show that the total landslide volume estimation has large uncertainties to be used to determine whether the Wenchuan Earthquake generates or reduces relief. Thus, the widely held view that large dip-slip and oblique-slip earthquakes build mountainous topography may still be applicable to the Wenchuan Earthquake in Longmen Shan area. To challenge this view, simple landslide volume and co-seismic uplift comparison is not enough, i.e., more data are needed.

关键词： Wenchuan Earthquake landslide mass wasting topographic generation.

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Platinum-group Element Geochemistry of Magnetite from Porphyry-Cu-Mo Deposits and their Host Rocks(Siberia,Russia)

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Acta Geologica Sinica(English Edition) 2012年第1期86卷 106-117页

作者： Anita BERZINA institute of geology and Mineralogy Novosibirsk630090Russia

The concentrations of platinum-group elements （PGE） have been analyzed in primary magmatic magnetite samples from the Zhireken, Shakhtama and Aksug porphyry Cu-Mo deposits （Siberia, Russia） by laser ablation-inductively coupled plasma mass spectrometry to determine the range of PGE contents in magnetites and to check whether magnetite from two main rock suites （barren plutonic suite and mineralized porphyry suite） has distinct PGE composition. The results presented here indicate that magnetites are enriched in PGE relative to whole-rocks. Comparison of ore-related porphyry and barren plutonic suites shows that magnetite exhibit relatively similar PGE distribution patterns in both suites. Variations in Rh and Ru contents were controlled by the oxygen fugacity during magma crystallization.

关键词： magnetite platinum-group elements porphyry Zhireken Shakhtama Aksug Siberia,Russia

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Thermal regime transition in eastern North China and its tectonic implication

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Science China Earth Sciences 2005年第6期48卷 840-848页

作者： FU Mingxi HU Shengbiao WANG Jiyang institute of geology & Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology & Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology & Geophysics Chinese Academy of Sciences Beijing 100029 China

The pre-Cenozoic formation in the Cenozoic depositon centres in eastern North China reached its maximum temperature at present, and the earlier paleo-temperature, therefore, has been overprinted, but the record of paleo-temperature by the vitrinite reflectance (Ro) has not been overprinted by the later thermal events in the pre-Cenozoic formation located in the uplift or in the Paleozoic-Mesozoic residual basins out of the Cenozoic depositon centres. The reconstruction of paleo-temperature gradient and paleo-heat flow, based on the vitrinite reflectance in the Paleozoic and the Mesozoic structural layers in boreholes, indicated that the eastern North China was characterized by much higher paleo-temperature gradient (40-55℃/km) and heat flow (>80 mW/m2) during the Middle-Late Mesozoic than those in the Early Mesozoic and at present. The higher paleo-heat flow during the Middle-Late Mesozoic implies that the thickness of the 'thermal' lithosphere at that time was just 50-55 km, it had been much thinned relative to the thickness (135-148 km) at the Early Mesozoic. The transition of near-surface thermal regime in eastern North China occurred around 110 Ma, and the corresponding deep tectonothermal processes should take place at ~160 Ma.

关键词： eastern North China, thermal regime, paleo-heat flow, "thermal" lithospheric thickness, thinning of litho-sphere.

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Mesozoic basins and associated palaeogeographic evolution in North China

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Journal of Palaeogeography 2015年第2期4卷 189-202页

作者： Yong-Qing Liu Hong-Wei Kuang Nan Peng Huan Xu Peng Zhang Neng-Sheng Wang Wei An institute of geology Chinese Academy of Geological Sciences

In North China, the Mesozoic terrestrial basins, sedimentary palaeogeography and tectonic settings involved five evolutionary stages：（1） the Early-Middle Triassic, （2） the Late Triassic to Early-Middle Jurassic, （3） the Late Jurassic to early Early Cretaceous, （4） the middle-late Early Cretaceous and （5） the Late Cretaceous. The regional punctuated tectonic events occurred during these evolutionary stages. During the Early-Middle Triassic （stage 1）, the Xingmeng Orogenic Belt （XMOB, i.e., east- ern part of Central Asia Orogenic Belt, CAOB） of the northern North China was settled in the transition of tectonic environment from syn-orogenic compression to post-orogenic extension with intensive uplifting. It is a main provenance in the unified Ordos-North China *** united continental plate of China and the Qinling-Dabie-Sulu Orogenic Belt formed due to convergence and collision between the North China Plate and the Yangtze Plate along two suture zones of the Mianlue and the Shangdan in the terminal Middle Triassic. During the Late Triassic to the Early-Middle Jurassic （stage 2）, the Late Triassic mafic or alkaline rocks and intrusions occurred on the northern and southern margins of North China Craton （NCC） and XMOB, implying that intensified extension happened all over the North China （early phase of stage 2）. Additionally, in the late phase of stage 2, the basic volcanic- filing faulted basins were widely distributed in the northeastern North China during the Early- Middle Jurassic, including a series of smalt- to medium-sized basins with coal-bearing strata and some volcanic rocks in other areas of North China, which was the result of subduction of the Palaeo-Pacific Plate during the Early-Middle Jurassic. An active continental margin with accretionary complex developed in the eastern Heilongjiang of China, Japan and the Far East of Russia at that time. However, in the end of the Early-Middle Jurassic, because of the Yan- shanian orogeny characterized by com

关键词： Mesozoic basin orogenic belt tectonic zone palaeogeography North China

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