2016 Vol. 22, No. 4

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Chief Editor’s Address
2016, 22(4): 803-808.
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EXPLORATION OF GEOLOGICAL MAPPING METHODS ON COVERED AREA OF FAULTED BASIN IN THE NORTHWEST CHINA: A MAPPING PRACTICE IN THE BARKOL BASIN, XINJIANG
WANG Guo-can, ZHAO Xuan, CHEN Chao, CHEN Yue, JI Jun-liang, WANG An, CAO Kai
2016, 22(4): 809-821.
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The geological texture of bedrock surface and overburden cover, and the basin-mountain coupling relationship are the key and difficult points in the regional geological survey of the covered areas of faulted-basin in the western China. In this paper we sorted out the mapping target and mapping contents to the covered region of faulted-basin based on the geological mapping practice in the Barkol basin, emphasized that the geological survey in the covered region must be aimed to solve the key geological problems and combination of surface geological survey, geophysical exploration and drilling verification, and determined the general mapping technical route and the combination of mapping methods. As an example, this paper also systematically introduced the mapping methods in the Barkol faulted-basin, including determining mapping targets and contents, optimizing geophysical exploration methods, and laying out drilling work.
MULTI-LEVEL GEOLOGICAL MAPPING APPROACHES OF THE PLANE AREA AND APPLICATIONS: A CASE STUDY IN 1: 50000 SHEETS OF GANGKOU, TAIXIAN, ZHANGDIANGONGSHE, TAIXINGXIAN AND SHENGCITANGZHEN
LI Xiang-qian, ZHAO Zeng-yu, CHEN Yu, GUO Gang, SHENG Jun, JIN Yong-nian, ZHAGN Xiang-yun
2016, 22(4): 822-836.
Abstract (137) HTML (72) PDF (4830KB)(30)
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To take geological survey of 1:50000 sheets of Gangkou, Taixian, Zhangdiangongshe, Taixingxian and Shengcitangzhen for an example, geological mapping technologies for three depth levels of shallow (0 to 4 m), Quaternary and bedrock depth have been discussed in this paper. Different combination of effective mapping methods should be selected to determine different mapping targets of different depths. Shallow deposits are mapped by the methods of groove drilling, DEM analyzing and RS (remote sensing) image interpretation. The stratigraphic framework of Quaternary deposits is established by combination of drilling and integrated geophysical logging. The bedrock geological characteristics are studied according to the regional magnetic data combined with the shallow seismic exploration method. These geological methods could obtain geological information effectively. The multi-scale three-dimensional geological models of different depth and precision are established based on a variety of geological information. The multi-level geological structure characteristics are presented by three-dimensional modeling, which enriches 1:50000 geological mapping results. Finally, the applications of different level mapping results are discussed, leading the way of expression and application of 1:50000 geological mapping results in plane area.
EXPLORATION AND PRACTICE OF 1: 50000 GEOLOGICAL MAPPING TECHNIQUES FOR ALPINE-GORGE AREA: A CASE STUDY IN BEISHAN AREA OF WUSHI, XINJIANG
GU Ping-yang, CHEN Rui-ming, CHA Xian-feng, ZHUANG Yu-jun, HU Chao-bin, LI Pei-qing, CHA Fang-Yong, LI Lin, Guo Ya-ping
2016, 22(4): 837-855.
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The 1:50000 geological mapping project makes sufficient use of remote sensing technologies to explore new methods of geological mapping in alpine-gorge area of Wushi, Xinjiang. Different spatial resolution remote sensing data can reveal different characteristics of lithology and structures. Integrated interpretations of multi-source remote sensing data can enhance the ability of interpretation effectively. Higher accuracy interpretations of lithologic classification can be obtained by combination of different bands of the same remote sensing image according to the optimum index factor (OIF) and synergestic images of Landsat-8 and worldview-2. Hyperspectral mineral mapping and lithology identification, petrochemistry components mapping using ASTER thermal infrared remote sensing data are useful technologies of geological mapping in alpine-gorge area. Both of the ETM and ASTER data were used to extract alteration information. The result shows that the ASTER data is more useful than ETM data in extracting alteration anomalies, such as ferric contamination anomaly and hydroxyl anomaly. Therefore, it is an important way of multivariate information comprehensive analysis to prospect. Based on the geological and geomorphological features, effective techniques have been selected to complete 1:50000 geological mapping of the North Mountain, Wushen area, and important research results have been obtained. The sufficient use of remote sensing data can reduce the amount of geologic section and geological survey routes, and achieve the mapping precision.
REGIONAL GEOLOGIC INVESTIGATION METHODS IN NEOTECTONIC AND ACTIVE TECTONIC AREA: EVIDENCE FROM 1: 50000 REGIONAL GEOLOGIC MAPPING IN NEOTECTONIC AND ACTIVE TECTONIC AREAS INCLUDING HONGYAZI, DABAZHAN AND QINGTONGXIALVCHANG IN NINGXIA
SHI Wei, CHEN Hong, LI Zhen-hong, GONG Wang-bin, QIU Shi-dong
2016, 22(4): 856-867.
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New requirement on regional geologic investigation was proposed by Geological Survey of China in new era. How does the regional geologic investigation in Neotectonic and active tectonic area as one of special geology and geomorphy areas be conducted in new epoch? In this work, we have carried out new geologic investigation in Ningxia area, named as "1:50000 regional geologic mapping in neotectonic and active tectonic areas including Hongyazi, Dabazhan and Qingtongxialvchang", and suggest a set of regional geologic mapping method on Neotectonic and active tectonic area. The geological mapping in new epoch should meet the requirements of the national and local economy, and yield multitasking, multidisciplinary and multilevel regional investigation fruits based on big data.
APPLICATION OF FLUVIAL DEPOSITIONAL SYSTEM ANALYSIS DURING THE QUATERNARY GEOLOGICAL SURVEY IN THE SHALLOW COVERED AREA: A CASE STUDY OF 1: 50000 GEOLOGICAL MAPPING IN THE HETAO REGION OF INNER MONGOLIA
LIU Xiao-tong, ZHANG Xu-jiao, YE Pei-sheng, JIA Li-yun, CAI Mao-tang, HE Ze-xin, LI Cheng-lu, WU Ze-qun, ZHOU Qing-shuo
2016, 22(4): 868-881.
Abstract (115) HTML (54) PDF (3479KB)(16)
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With the conduction of the national large-scale (1:50000) geological survey in special geological and geomorphic areas, traditional Quaternary mapping methods could not meet the needs of modern geological mapping in the coverage areas. Therefore, "What can we do" and "How can we do" become the key issues for the geological workers during the Quaternary geological mapping. In order to test even find some new geological mapping methods, we select typical coverage area-Hetao plain as our study area. Under the guidance of theories in fluvial sedimentlogy, combined with drilling column, we build the fluvial sedimentary system since the Holocene. Regard these subfacies as the sedimentary frame for the geological sketch frame, we recognize fluvial subfacies, embankments subfacies, and flood plain subfacies. The principle of step by step approximation was applied to determine the geological boundary. Besides that, three periods of fluvial deposits and corresponding sedimentary systems were recognized. Therefore, the problem of lacking geological units during the Quaternary geological survey in covered area might be solved, and a set of feasible scheme could be provided.
APPLICATION OF REMOTE SENSING INTERPRETATION FOR 1: 50000 GEOLOGIC MAPPING IN LANGSHAN GOBI DESERT AREA, INNER MONGOLIA
HE Peng, TENG Xue-jian, LIU Yang, TENG Fei, GUO Shuo, WANG Wen-long, TIAN Jian, DUAN Xiao-long
2016, 22(4): 882-892.
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In order to improve the spatial and spectral resolution of images, we adopt image fusion, image correction and image enhancement to process ASTER and SPOT5 data for geological mapping of special geological and geomorphic areas in Gobi desert of Inner Mongolia. As a result, interpretation markers for the stratum, intrusive bodies and structures can be established quickly and precisely. Then, the geological mapping accuracy can be improved after comprehensive analysis by combining field work and remote sensing image interpretation. So, this combination can be served as a guideline for geological mapping in similar areas.
APPLICATION OF GEOPHYSICAL AND GEOCHEMICAL PROSPECTING TECHNIQUES IN SPECIAL GEOLOGICAL AND GEOMORPHIC AREAS
YU Jin-song, JING Lei, WANG Qiao-lin, HAN Wei, LIU Hua-zhong, GAO Xiao-liang
2016, 22(4): 893-906.
Abstract (130) HTML (56) PDF (4003KB)(10)
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Based on the application experiment of geophysical and geochemical prospecting technique in special geological and geomorphic areas mapping, this paper introduces the methods of extracting geologic information from regional geophysical and geochemical data. It is pointed out that the combination of gravity and Rn-Hg survey is efficient and low-cost for detecting concealed rock and fault in coverage areas. The weathering grades of intensely weathered areas can be clarified into bedrock, weak weathering, moderate weathering, strong weathering, total weathering, residual soil, and so on. Besides that, the geochemical behavior of weathered crust has a trace effect on the decomposition of primary minerals and the formation of secondary minerals. Due to the significant differentiation of REE in different weathered layers, the distribution pattern of REE which are strongly enriched in the whole weathering layer (rock-soil interface or weathering rock top) can be used as an important geochemical identification index for delimiting weathering crust.
LITHOLOGICAL INFORMATION EXTRACTION IN MOUNTAIN CANYON REGION BASED ON MULTI-SOURCE REMOTE SENSING DATA: A CASE STUDY OF 1: 50000 PILOT GEOLOGICAL MAPPING IN BEISHAN AREA IN WUSHI, XINJIGAN
MENG Peng-yan, SUN Jie, YU Chang-chun, MU Chao, SHUAI Shuang, XIE Fei, MENG Dan
2016, 22(4): 907-920.
Abstract (179) HTML (80) PDF (4860KB)(5)
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The location of 1:50000 pilot geological mapping program in Beishan, Wushi County, lies at the junction point of north-west margin of Tarim basin and south-west of Tianshan. According to the geomorphic characteristics of high altitude and deep negative relief, the study area belongs to alpine valley region. Based on the typical lithology spectral absorption characteristics, we carried out some research on the enhancement and absorption of lithologic differences information, and summarized a series of methods to divide the lithological units margins according to multi-source remote sensing data. On the foundation of ASTER, ASTER and SPOT6 cooperative data, ASTER and GF-2 cooperative data, we choose the best wave combination to synthesize RGB color and enhance the difference between images. And we preliminarily mark the boundaries of different image units according to the known geological data of study area. Then, the final lithology units can be interpreted by combining field survey data, realistic geological background, and geomorphic images. Thus, the study results provide reference for further optimized stratum division and comparison.
APPLICATION OF REMOTE SENSING TECHNOLOGY IN THE 1: 50000 REGIONAL GEOLOGICAL SURVEY IN KARST AREA: A CASE STUDY OF NORTHWEST GUIZHOU
CHENG Yang, LÜ Yong, TU Jie-nan, TONG Li-qiang
2016, 22(4): 921-932.
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Karst region in Southwest China has special resources and environmental characteristics. According to these characteristics, this paper uses the multi-temporal, multi-source and multi-scale remote sensing data and applies the remote sensing technology of automatic extraction of remote sensing information and interactive interpretation to 1:50000 regional geological survey in karst area. This study provides a series of maps that are beneficial to the regional geological mapping in karst area and improves the efficiency of 1:50000 regional geological survey. Through this research, a remote sensing technology method for 1:50000 regional geological survey in karst areas in Southwest China is established, which can help researchers quickly and accurately interpret the special karst geology, geomorphology, environment, hydrology and other factors, and provide technical support for geological mapping special geological landform area.
APPLICATION OF UNMANNED AIR VEHICLE (UAV) REMOTE SENSING DATA IN THE RECOGNITION OF STRATIGRAPHIC UNITS: A CASE STUDY OF 1: 50000 PILOT GEOLOGICAL MAPPING OF KARST AREA IN SOUTHWESTERN CHINA
SHAN Ke-qiang, PAN Ming, LIN Yu
2016, 22(4): 933-942.
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As microgeomorphologic characteristics formed by different units are the basis of the large scale interpretation remote sensing of lithostratigraphic units, it is very important to increase the resolution of remote sensing images and terrain data. During proceeding the project of the 1:50000 mapping pilot of karst area of southwest China, we use the Unmanned Aerial Vehicle (UAV) platform to obtain high resolution images (0.2 m), high density point cloud data and 0.5 m resolution DEM data of our working area. According to these data, it is easy to describe the microgeomorphologic characteristics of surface objectively by reproducing the high definition real 3D model of microgeomorphology in the working area, to advance the precise researches of microgeomorphologic characteristics of different kind rocks and to improve the interpretation degree of remote sensing data. Combing the existing geological data, interpretation indexes of different microreliefs, colors and vegetation of different stratigraphic unit are set up based on the surface 3D model.
GRAVITY, MAGNETIC AND ELECTRIC COMPREHENSIVE GEOPHYSICAL PROSPECTING FOR DEEP STRUCTURES IN HETAO BASIN
LIU Rong, MA Jian-qing, LI Qing-chun, YE Pei-sheng
2016, 22(4): 943-954.
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The gravity, magnetic, and electrical methods have been used to reveal the structure developed in the deep covered area of the Hetao Basin. We have carried out a lot of research on the characteristics of the northern and southern boundary faults, the features and thickness of Quaternary sediments and the structures developed in the basement of the Hetao Basin. A preliminary study on the distribution of Quaternary aquifer in this area was made by using electrical resistivity method. The joint inversion results of gravity and magnetic data, and earthquake data have been analyzed. And four concealed fault F1 to F4 from south to north and Langshan-Seertengshan piedmont fault F5 have been revealed. The fluctuation and buried depth of the crystalline basement in the area have been revealed. Depth of the basement in the southern part of the study area is about 2.5~4.2 km, and which in the northern part is up to 6 km. North Adjacent to the Seertengshan piedmont fault, the basement rock has been uplifted to about 0-1 km.
APPLICATION OF REGIONAL GEOCHEMICAL DATA IN GEOLOGICAL MAPPING IN STRONGLY WEATHERED AREA IN SOUTHERN CHINA
WU Jun, BU Jian-jun, XIE Guo-gang, PENG Xing-fang
2016, 22(4): 955-966.
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Since Regional Geochemistry-National Reconnaissance Program (RGNR) carried out in 1978, the immense amount of geochemical data obtained played a big role in mineral exploration, environmental, ecological and agricultural studies, but its application in geological mapping was quite less. In southern China, granites are widespread and covered by thick intense chemical weathered layers and vegetations, which severely affected the speed and accuracy of geological mapping. Some geochemical maps prepared by using regional geochemical data showed a significant geochemical partition. According to field validation, the chemical zones coincide well with the outcrops of granitic intrusions of different ages. So this can increases the efficiency and accuracy of geological mapping in strongly weathered areas.
STUDY ON SEISMIC PROPERTY OF CRACK-INCLUDED PHYSICAL MODEL
ZHAO Wei-hua, WEI Jian-xin, SUN Dong-sheng, LI A-wei, WANG Hong-cai
2016, 22(4): 967-975.
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It is very helpful in petroleum production, groundwater exploration and to disposal of pollution to investigate the seismic property of the crustal rocks included cracks or fractures. Two group physical models with the same diameter varying crack density and the same density varying diameters were constructed. The seismic velocities were measured under different confining pressure and calculated by numerical simulation based on Hudson theory. The calculated and measured results show that the Vp and Vs nearly increase linearity and there anisotropy keep nearly stable constant with confining pressure. Vp circles decrease with the crack density varying from 2% to 6%. Moreover, the slow Vp decrease more amplitude than the fast Vp which maintains nearly stable, the Vp and Vs anisotropy all increase with the crack density ranging from 2% to 6%.With the crack diameter varying from 2 mm to 3 mm, the Vp increases, but the Vp anisotropy decreases, Vs and the Vs anisotropy nearly remain constant. Comparing the experimental and the theoretical calculated results, new conclusion of Hudson theory used in different depth was discussed, and the primary constraint of its application were analyzed. It is very helpful in petroleum production, exploration of groundwater and disposal of pollution to investigaste the seismic property of the crustal rocks with cracks or fractures.
JOINT INTERPRETATION OF DUAL POLARIZATION SAR AND MULTISPECTRAL OPTICAL IMAGES FOR GEOLOGICAL MAPPINT IN STRONGLY WEATHERED ZONE IN SOUTHERN CHINA
PEI Yuan-yuan, DENG Fei
2016, 22(4): 976-983.
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Most of the geological bodies are covered by different thickness of weathering layers and dense vegetation due to the warm and humid climate in South China. Therefore, most optical remote sensing images reflect the spectral information of the vegetation layer, and which resulted in the difficult for the geological interpretation and mapping. In this paper, the ALOS-PALSAR dual-polarized SAR images and the Landsat8 OLI multi-spectral images have been interpreted jointly in Luoding area, western Guangdong. The result showed that joint interpretation can effectively increases identifiable species of lithology, and could be popularized for the mapping in strongly weathered areas of south China.
SEDIMENTATION OF THE PLIOCENE-PLEISTOCENE CHAIZHUANG SECTION IN THE CENTRAL OF LINFEN BASIN, NORTH CHINA AND ITS TECTONIC SIGNIFICANCE
CHEN Xing-qiang, SHI Wei, HU Jian-min, DONG Shu-wen
2016, 22(4): 984-993.
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Linfen Basin is located in middle-southern part of the Fenwei Graben systems, North China Craton. As a late Cenozoic rift basin, it was defined by the northeast-striking and east-striking normal faults. Comprehensive constraints of sedimentary facies and provenance of the Chaizhuang section in the middle part of the basin indicating that the section can be divided into three units with different source areas, with some loess on the top of the section. This may provide important clues for exploring the tectonic setting of the basin evolution. Unit 1 in Pliocene (5~2.6 Ma) was deposited in alluvial fan and eolian environment with the nearby sedimentary rocks (i.e. limestone) to be the main source rocks. Unit 2 in the lower part of the Pleistocene (2.6~1.0 Ma) was deposited in a delta environment with mixed source rocks shed from Taihang Mountains and Zhongtiao Mountains on the eastern and southeastern of the basin, which include the Archean-Palaeoproterozoic granitic gneiss and gneiss, Neoproterozoic-Paleozoic carbonatite, Mesozoic terrigenous clastic rocks and some granitoids. Unit 3 in the upper part of the Pleistocene ( < 1.0 Ma) was deposited in a fluvial environment with the acidic magmatic rocks derived from the Taihang Mountains on the northeastern of the basin. Combined with the late Cenozoic regional regime evolution of the Shanxi Graben, we proposed that the northeast-striking normal faults were strongly active in Pliocene and influenced by the transtensional stress regime under NW-SE extension. The east-striking faults seem to be active in early Pleistocene (2.6~1.0 Ma) and were influenced by the NE-SW extension. From 1.0 Ma, the fluvial replaced the delta and lacustrine sedimentary environments. This indicates that the basin evolution is not as strong as in early Pleistocene which may be a result of the weakening of the extension. All these clues indicate that the main tectonic transition ages in Fenwei Graben systems influenced by the Tibetan in Pliocene-Pleistocene may include Late Miocene-early Pliocene (5.0 Ma), 2.6 Ma and 1.0 Ma.
MAGNETOSTRATIGRAPHY AND HEAVY MINERALS RECORDS OF TZK9 CORE IN SUBEI BASIN
CHENG Yu, LI Xiang-qian, ZHAO Zeng-yu, ZHANG Xiang-yun, GUO Gang
2016, 22(4): 994-1003.
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The core TZK9 is located in the northeast Taizhou city (N 32°35', E120°6'), the south of Subei Basin. The main kinds of lithology in the core are clay and silty clay. Some silt, sand and coarse sand are also found. In this study, 382 samples at 30~60 cm intervals were taken for paleomagnetic measurements, and 17 samples for heavy minerals test. Magnetostratigraphic results show that, the M/G and B/M are found at the depth of 250.3 and 78.5 m, respectively. Extrapolation with accumulation rates suggest that the basal ages for sediments in this core is about 3.0 Ma. ATi index was from 50.97 to 100, while GZI index was 11.48 to 77.81, indicating that the source was metamorphic and igneous rocks. During 3.0~2.6 Ma, the main heavy minerals of TZK9 core were ilmenite, epidote, magnetite, garnet and zircon. Comparing the heavy minerals of the TZK9 core with Huai river and Yangtze river, it shows that the sediment came from the Huai river during this time. During 2.6~0 Ma, the main heavy minerals are ilmenite, epidote, zircon, apatite, garnet and magnetite. The content of zircon, apatite, tourmaline, rutile increases compared to the previous period, and it indicates that the Yangtze river begin to influence this area in this period. And the ZTR index gradually increased since 2.6 Ma, which may be related to the change of global climate.
QUATERNARY ACTIVE CHARACTERISTICS OF THE LIUMUGAO FAULT IN THE NORTHERN SEGMENT OF THE NIUSHOUSHAN-LUOSHAN FAULT
GONG Wang-bin, SHI Wei, CHEN Hong, QIU Shi-dong, YIN Yan-guang, ZHAO Yi
2016, 22(4): 1004-1014.
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The Niushoushan-Luoshan fault is located in the northeastern margin of the arcuate structure zone in the northeastern Tibetan Plateau, consisting of Guyuan, Eastern Luoshan, Niushoushan and Sanguankou faults from south to north. In this study, we defined the geometry and kinematics, and evolution of the Liumugao fault, which is the northern segment of the Niushoushan fault, during the Quaternary earthquakes through remote sensing interpretations, field observations and trench investigations, and bracketed the occurrence of Holocene earthquakes according to the analyses of cut-off relationship and age dating. We concluded that, the fault was dominated by NE-directed thrusting during Pliocene to late Pleistocene, followed by sinistrallateral torsional movement during late Pleistocene to pre-Holocene, which presented as positive flower structure, and normal faulting during Holocene. And the paleo-earthquake occurred after 1690±30 BP (Cal AD 320~415). The Liumugao fault might be the seismogenic fault of the Mw 6.5 south Qingtongxia earthquake in A.D. 876.The kinematic characteristic of Liumugao fault during Pliocene to late Pleistocene is consistent with the Guyuan, Eastern Luoshan and Niushoushan faults, which might result from the ongoing northeastward movement of the Tibetan Plateau. The Holocene normal faulting might be controlled by the extension of Yinchuan graben.
GEOCHRONOOGICAL AND GEOCHEMICAL STUDY OF THE LATE TRIASSIC LAYERED MAFIC-ULTRAMFIC INTRUSIONS IN BEISHAN AREA OF WUSHI COUNTY, SOUTHWEST TIANSHAN
HU Chao-bin, LI Pei-qing, GU Ping-yang, CHEN Rui-ming, ZHA Xian-feng, ZHUANG Yu-jun
2016, 22(4): 1015-1031.
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Layered Mafic-ultramafic intrusions, which carry abundant information of mantle and provide an excellent approach to probe the mantle material composition, plate tectonic and deep geological process, are generally considered to be an important symbol of lithosphere extension, We discovered a suit of layered Mafic-ultramafic intrusions in Southwest Tianshan area, and obtained the zircon U-Pb age of gabbros of 224±4 Ma. These rocks are characterized by the enrichment of LREE, H2O, Na2O+K2O and incompatible elements such as Th, U, Nb, Ta, etc., and depleted in HREE. They might be derived from enriched mantle, which is formed by low degree partial melting of garnet lherzolite. The primary magma may be high Mg basaltic magma which was rich in iron and titanium and mainly controlled by the fractional crystallization. This magam in the continental orogenic stage was actived in the environment of intracontinent orogen after the closure of the South Tianshan ocean and post collisional orogeny, which derived from mantle in the envirnment of extensional environment. We can concluded that the Southwest Tianshan area was under an extensional tectonic seting during late Triassic.
PETROGENESIS AND TECTONIC SIGNIFICANCE OF EARLY CARBONIFEROUS A-TYPE GRAINTE IN HARLIK, XINJIANG
WANG Liang-yu, LIAO Qun-an, XIAO Dian, LUO Ting, ZHAO Hao, LIU Hong-fei, WANG Guo-can
2016, 22(4): 1032-1048.
Abstract (367) HTML (137) PDF (5050KB)(3)
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The alkali-feldspar granite is located at the area of Nanshankou, western part of the Harlik Mountain. Its LA-ICP-MS zircon U-Pb age is 331.3±1.9 Ma. Therefore, the granite is formed in the late stage of Early Carboniferous. The dark minerals in the rock are mainly biotite, with litte Na amphibolite. This type of granite is riched in alkali elements, poor in calsium, magnesium, and has low content of aluminum and iron oxide. The rock is riched in large ion lithosphile elements, such as Rb, Th and K. It has abundant HFSE elements and depleted in Ba, Sr and Eu. The 10000 Ga/Al value is varied from 2.93~3.80. It indicates that the rock is A-type granite, formed in intraplate tectonic settings, instead of the previous island arc environment. Its εNd(t) values range from 5.66 to 6.12, the Nd model ages are 600~620 Ma. It tells that the magma may originate from the young crust. Based on the results of the 1:50000 regional geological survey, the Bogada rift was extended during Early Carboniferous, and closed at the late stage of Early Carboniferous. The Late Early Carboniferous alkali-feldspar granites should formed in the rift environment, instead of coming from the previous post-collisional or arc tectonic setting.
PETROGENESIS AND TECTONIC IMPLICATIONS OF TWO TYPES EARLY SILURIAN GRANITES IN EAST JUNGGAR
XIAO Dian, LIAO Qun-an, WANG Liang-yu, ZHAO Hao, ZHA Yan-hong, ZHAO Hong-wei, YIN Ting-wang, TIAN Jin-ming, LIU Hong-fei
2016, 22(4): 1049-1061.
Abstract (239) HTML (78) PDF (4346KB)(8)
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The early Silurian monzogranite and syenogranite are located in the western section of Harlik Mountain with a NWW-trending, which intrude into the Ordovician Tashui Formation (O1-2t). The LA-ICP-MS zircon U-Pb dating shows their emplacement ages are 438.8±2.3 Ma~435.8±3.1 Ma. The rocks have high contents of silicon (SiO2=73.0~77.8%)and potassium (K2O=3.31~4.26%), and low contents of magnesium (MgO=0.03~0.59%), with moderate aluminum saturation index (A/CNK=1.02~1.08), which show that the rocks are high-K calc-alkaline, weakly peraluminium series. Monzogranites exhibit strongly fractionated REE patterns with moderate negative Eu anomalies, and they are depleted in Nb, Ta, Ti, P, but enriched in Rb, Ba, K, showing notable fractionated Ⅰ-type granitoids with mafic lower continental crust as a potential magma source. Syenogranites show remarkably depletion of Eu, P, Ti and Sr, and enrichment of Rb, K, Zr and Hf, showing A-type granites affinity, whose magma source maybe the dehydrated felsic upper continental crust. Combined with the stratigraphic unconformity in this region, we propose that the East Junggar is in a post-collisional setting rather than arc-related setting during the early Silurian. The upwelling asthenosphere provided enhanced heat flux and triggered the partial melting of the juvenile crust, and resulted in the generation of various Silurian post-collisional granites in East Jungga.
J.S.LEE: EARTH SYSTEM SCIENCE PIONEER
LI Dong-xu, LONG Chang-xing
2016, 22(4): 1062-1066.
Abstract (217) HTML (96) PDF (1837KB)(9)
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J.S.Lee's research on Earth System Science and structural geology are reviewed. As a field, Earth System Science was established by the 1980's. It is generally believed that this idea was first proposed by NASA. However if we look at J.S.Lee's early works during the 1920's to 1930's, we find that he had already started using the ideas of earth systems:tectonics, continental brake hypothesis, transgression-regression theory, etc. His "Astronomy, geology, and Paleontology" published in 1970 exemplified the ideas of Earth System Science. As another example, "Geomechanics" can be considered as the combination of structural geology, and Earth System Science and confirms J.S.Lee as a pioneer and innovator in this field. As earth system scientists in China we should cherish and further develop this legacy.

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