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2009, Volume 16 Issue 2
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Permian and Early Cretaceous tectonomagmatism in southern Tibet and Tethyan evolution: New perspective. SHU Di-Cheng MO Xuan-Hua DIAO Zhi-Dan NIU Yao-Ling BO Gui-Tang WANG Li-Quan LIAO Zhong-Li 2009, 16(2): 1-20.  Abstract ( 2564 )   PDF (4660KB) ( 1312 )   The preCenozoic evolution of the Tethys and the Cenozoic uplift of the Tibetan Plateau have long been considered as two important issues of fundamental geology of this plateau. However, our knowledge on the geological context and preCenozoic history of the Tibetan Plateau remains limited so far, consequently raising uncertainties for further exploring the history of Tibetan uplift during the Cenozoic. New available geological and geochemical data of volcanic rocks indicate the coexistence of an islandarc system in the Gangdese and an extensional setting in the Himalayas during the Early to Middle Permian. Peraluminous Stype granites near Pikang (~263 Ma), the Songdo eclogite of the same metamorphic age (~262 Ma), and the regional angular unconformity between the Middle and the Upper Permian from the same geotectonic location suggest that the presentday Gangdese Retroarc Uplift Belt (GRUB) experienced a syncollisional orogeny at the latest Middle Permian (~263 Ma). UPb age dates and Hf isotopic compositions of zircons from Mesozoic magmatic rocks reveal that the GRUB and Middle Gangdese are characterized by an ancient basement of Paleoproterozoic (as old as Archean) age, whereas the Northern and Southern Gangdese are dominated by MesoNeoproterozoic and Phanerozoic juvenile crust, respectively. Available good quality age dates and zircon Hf isotopic data suggest that the northern parts of the Gangdese experienced a zonal magmatic flareup with strong input of mantlederived materials at ~110 Ma. New reliable UPb age dates of the extensive Cretaceous igneous rocks in the eastern Himalayas suggest that these rocks were emplaced at about 132 Ma, and may represent the erosional and/or deformational remnants of the newly identified ComeiBunbury large igneous province. All these new data formed a basis for discussing the tectonomagmatic and Tethyan evolution in presentday southern Tibet during the Late PaleozoicMesozoic. Related Articles | Metrics

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Yanshanian largescale magmatism and lithosphere thinning in Eastern China: Relation to large igneous province. ZHANG Qi JIN Wei-Dun LI Cheng-Dong WANG Yuan-Long 2009, 16(2): 21-51.  Abstract ( 2462 )   PDF (6291KB) ( 1282 )   In this article, we expound the relationship between the largescale magmatism and lithosphere thinning, and suggest that the lithosphere thickness is equal to the crust thickness when the asthenospheric mantle contacts the crust directly, namely, the lithosphere being the thinnest (the thickness of lithospheric mantle is equal to 0). The lithosphere in the Eastern China is thick except in the Yanshanian. We have discussed the relationship between the largescale magmatism and the plate subduction in Eastern China, and pointed out that there are no relations between the magma activity and the ancient Pacific Ocean plate in  Eastern China during the Yanshanian. This conclusion is based on the following considerations. (1)  Eastern China does not belong to the CircumPacific Ocean tectonics belt, and is not the Andeantype active continental margin. (2) The basalts are not of the island arc basalt characteristic in the Mesozoic era, and the acid magma activity can not induce an island arc settings. (3) The expanding direction of the ancient Pacific Ocean plate during the Triassic period does not support the view of the plate subduction westwards either. The super mantle plume may have caused the largescale magmatism during the Yanshanian in  Eastern China, and may have been a new type of the large igneous province (LIP). We divided the large igneous province into two types: One is the Btype LIP, which is partially melted in the lithosphere bottom and characterized by the development of basalt. Another is the Gtype LIP, which is partially melted in the crust bottom and characterized by the development of largescale granitoid magma. Five large igneous provinces have been differentiated according to the spacetime distribution of the largescale magmatism in Eastern China. They are the Okhotsk LIP (in the north part of Da Hinggan Mountain), the Zhangguangcai MountainXiao Hinggan Mountains LIP, the North ChinaDa Hinggan Mountain LIP, the South China LIP and the Coast of East China. The lithosphere thinning can cause many effects, and is the most important geodynamics of the crust evolution, and may have had no relation with the crust extension during the Yanshanian. We have reviewed the popular opinions on lithosphere thinning, and consider that the popular opinion of lithosphere thinning, which limits the timing of the lithosphere thinning in the Cenozoic era (lithosphere thickness 80120 km), is a paradox, not a scientific proposal. Related Articles | Metrics

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Discussion on geodynamic significance of the Emeishan basalts LIU Cheng-Yang SHU Ri-Xiang 2009, 16(2): 52-69.  Abstract ( 1712 )   PDF (2095KB) ( 1410 )   It had been accepted that the Emeishan large igneous province was generated by the mantle plume, yet the plume formation is still hotly debated Radiometric datings showed that the main phase of the Emeishan basalts is ~260 Ma, corresponding to the endGuadalupian mass extinction Recent numerical modeling suggested that the mantle plume activity was closely linked to both superchron and the mass extinction Therefore, probing into the age and duration of Emeishan basalts is of significance to the understanding of  the relationships among Emeishan mantle plume activity, the endGuadalupian mass extinction and the genesis of the Kiaman reverse superchron (KRS) Important progresses on these topics are reviewed in this paper Besides, on the basis of new paleomagnetic work, the relationships between the Emeishan basalts and the endGuadulupian mass extinction were discussed, as well as their geodynamic significance   Related Articles | Metrics

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Geochemistry and Tectonic significance of the Permian basalt in Shuanghu Area, Tibetan Plateau. LAI Chao-Cong QIN Jiang-Feng 2009, 16(2): 70-78.  Abstract ( 2068 )   PDF (1488KB) ( 914 )   his paper reports the petrological and geochemical characteristics of Permian alkaline and tholeiitic basalts in the Shuanghu Area, central Qiangtang Block. The alkaline basalts are enriched in LILE and LREE, compared with MORB; they have similar La/Nb ratios and higher Ti/V ratios; in the trace element tectonic setting discrimination diagrams, all the alkaline samples are plotted in the field of OIB. The tholeiitic samples have flat REE pattern that is similar to MORB; they have higher Ti/V ratios than those of the MORB; in the trace element tectonic setting discrimination diagrams, all the tholeiitic samples are plotted in the overlapping field between OIB and MORB; these features suggest that the tholeiitic basalt was derived from a relatively enriched mantle source. When coupled with the regional tectonic setting, it is considered that the Permian alkalinetholeiitic basalts association in the Shuanghu Area was formed in the rift valley setting, and their occurrence may indicate a process from rift valley to juvenile oceanic crust along the LongmucuoShuanghu tectonic zone. Related Articles | Metrics

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Two types of Cenozoic potassic volcanic rocks in West Qinling, Gansu Province: Their petrology, geochemistry and petrogenesis. YU Hua-Hui MO Xuan-Hua DIAO Zhi-Dan HUANG Hang-Kai LI Yong CHEN Yan-Fang HUI Yu-Fang 2009, 16(2): 79-89.  Abstract ( 2450 )   PDF (2010KB) ( 908 )   Two types of Cenozoic potassic volcanic rocks, kamafugite and potassic trachybasalt, were recognized in Lixian and Dangchang counties in West Qinling, Gansu Province (N104°20′N104°50′, E33°30′E34°10′). The first type, kamafugite, is plagioclasefree, consisted of Tirich phlogopite, melilite, leucite and nephelite. They have lower contents of SiO2 and Al2O3, but have high TiO2, CaO, MgO contents and K/Na and Mg# ratio whereas the second type, potassic trachybasalt, is abundant in plagioclase and  contains no phlogopite, melilite, leucite and nephelite. They have higher SiO2, Al2O3, (Na2O+K2O), and lower TiO2, CaO, MgO, and K/Na and Mg#, in comparision to the first type of rocks. The whole rock K/Ar and phlogopite 39Ar/40Ar ages of kamafugite range from 71 to 23 Ma, and the potassic trachybasalt yields the whole rock 39Ar/40Ar age of ~9 Ma. They are both Miocene magmatism. Both kamafugite and potassic trachybasalt are enriched in incompatible trace elements and LREE. The kamafugite (87Sr/86Sr=0704 030707 49, 143Nd/144Nd=0512 740512 94, εNd=1125.95) and the potassic trachybasalt  (87Sr/86Sr=0.704 120.705 22, 143Nd/144Nd=0.512 650.512 76, εNd=1.125.95) have similar Pb isotopic compositions (206Pb/204Pb=8374 618.998 6, 207Pb/204Pb=15.5295.669 3, 208Pb/204Pb=38.497 139.414) and both show plumerelated OIBlike features, suggesting a possible mixture of the geochemical endmembers of EM1, DMM and HIMU. Combining the available regional geological and geophysical research, the petrogenesis of the magmatism was studied. As a response and absorption to the IndiaAsia collision, the northeastward flow of the asthenosphere beneath the Tibetan Plateau along the 400 km depth interface was blocked by the North China craton, and caused a systemic sequences in West Qinling Region, including the strikeslip fault systems and pullapart basins in the shallow crust and the origin of the twotype magmatism in this work in deep lithosphere. This explanation is consistent with the lithology and plumelike geochemical features of the kamafugite and potassic trachybasalt, which are significantly different from the potassic magmatism within the plateau and its adjacent regions. Related Articles | Metrics

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Petrogenesis of Cenozoic basalts of Tianheyong, Inner Mongolia,  and its geological implications. YANG Zong-Feng LUO Zhao-Hua ZHANG Hua-Feng ZHANG Yong-Mei HUANG Fan SUN Chen-Guang DAI Jin-Gen 2009, 16(2): 90-106.  Abstract ( 4383 )   PDF (5248KB) ( 3530 )   The Tianheyong basalts are basanites, which at least can be subdivided into three types of mineral assemblage. In general, the Tianheyong basalts are characterized by low silicon (w(SiO2)=4397％4568％), enriched alkali (w(K2O+Na2O)=591％765％), enriched potassium (w(K2O)=204％289％), high contents of titanium (w(TiO2)=218％237％), high magnesium value (Mg＃=6876), and high contents of REE (∑REE=(2466232982)×10-6). The chondrite normalized pattern of REE shows a right inclined smooth line, extreme enrichment of LREE, significant fractionation of LREE and HREE, without obvious anomaly of Eu(δEu=090102) and Ce(δCe=096100); extreme enrichment of incompatible elements, especially with peak value in high field strength elements (HFSE) of Nb, Ta and Th, and OIBlike distribution patterns of multielements; the Tianheyong basalts also have high content of compatible elements: Co((391489)×10-6), Ni ((130257)×10-6) and Cr((138320)×10-6). All of the above characteristics as well as poorcrystallized, abundant peridotite inclusions, few xenocrysts, and elements covariation trend indicate that the Tianheyong basalts were solidified from primitive basaltic magma. Trace elements ratio of Ba/Rb (1235) and variation of alkali metals might indicate the metasomatism of fluids. Petrogenesis simulation indicates that the Tianheyong primitive basaltic magma may have been the product of polybaric melting column with nonmodal partial melting processes of enriched lherzolite, which straddle the boundary of garnetand spinelfacies lherzolite. Magma may have been originated from low partial melting of source rocks(~<5％), which have ~1％ partial melting of garnet lherzolite and 2％5％ partial melting of spinel lherzolite. The comprehensive analysis indicates that the induced mechanism of source rock partial melting may have been the edgedriven convection, which resulted in the Tianheyong basalts having the deepest origin depth compared with that of eastern Jining and Hannuoba basalts. Related Articles | Metrics

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Petrogenesis of the Neoproterozoic Baoxing Complex and its constraint on the tectonic environment in western margin of  Yangtze Craton LIU Shu-Wen YANG Kai LI Qiu-Gen WANG Zong-Qi YAN Quan-Ren 2009, 16(2): 107-118.  Abstract ( 2593 )   PDF (2663KB) ( 1201 )   Neoproterozoic Baoxing Complex in middle to lower metamorphic grade, located in western margin of  Yangtze Craton, consists mainly of metamorphic gabbroic, dioritic gneisses, tonalitic and granodioritic gneisses, and massive monzogranites The studies of petrochemistry and SmNd isotopes of  Baoxing Complex reveal that the gabbroic and dioritic magmas came from a congenetic magma derived from the partial melting of spinel lherzolites in depletive mantle, and that the magma was intensively contaminated by crustal materials during its emplacement The tonalitic and granodioritic magma were derived from the partial melting of metamorphic basalts in the lower crust And the monzogranitic magma was formed from partial melting of metagreywacks Integrating the lithological association, their trace elements, SmNd isotopic characteristics and petrogenesis, the Baoxing Complex must likely have been emplaced in an island arc tectonic background at the Neoproterozoic active continental margin of Yangtze Craton Related Articles | Metrics

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“Mantle signature” on the Indosinian granitoid belt in South Qinling, Central China. TIAN Wei DONG Shen-Bao CHEN Mai-Mai SHU Wen-Ping 2009, 16(2): 119-128.  Abstract ( 1877 )   PDF (1636KB) ( 1048 )   The Indosinian granitoid belt in South Qinling, Central China, is lithologically composed of diorite, monzodiorite, tonalite, granodiorite and granite, as well as widely distributed mafic microgranular enclaves and dykes within the intrusions. Majority (>50％) of samples have high Mg＃(<076), high Cr(>100×10-6,max=1 600×10-6), high Sr(>500×10-6) and high Ba(>1 000×10-6) content, i. e. having the “mantle signature”. The partial melting of garnet bearing metabasic rocks can explain high LREE, low HREE and high Sr, low Y characteristics of some samples, but cannot explain the “mantle signature”. Although simple mantle upwelling and adiabatic melting model is reasonable for producing mantlederived magma and mixing between basic and acidic magma, the enriched Sr, Nd isotope (ISr=0705 40708 5;εNd(t)=-152-917)of samples with mantle signature and the regional geological settings do not favor this model. Similarities to high Mg adakite and sanukitoid imply that the samples having mantle signature could be derived from direct partial melting of hydrous enriched mantle. Related Articles | Metrics

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Application of insitu isotopic analysis to granite genesis. SUN Jin-Feng YANG Jin-Hui TUN Fu-Yuan 2009, 16(2): 129-139.  Abstract ( 2459 )   PDF (1866KB) ( 4345 )   Granitoids and related mafic rocks are the main components of continental crust and are important in understanding the formation and evolution of continental crust. The origin of granitoids, i.e., the sources of magma and the petrogenetic processes, is the key to studying the geodynamics of continents and to understanding the processes of continental crust growth and lithospheric evolution. In recent years, insitu analysis shows the elemental and isotopic heterogeneity within a single mineral scale. The minerals should have the same isotopic compositions as their host magma. If the chemical and/or isotopic compositions of host magma changed, the compositional zones can record it. It is the heterogeneity of a single grain that makes the insitu mineral geochronology and isotopic analysis be a useful tracer to constrain the age, source and petrogenetic process of granites. With the development of secondary ion mass spectrometry (SIMS) and multiplecollector inductively coupled plasma mass spectrometry (MCICPMS) equipped with laser, the applications of insitu elemental and isotopic analysis advanced the studies of origin of granitoids, especially the source of magma and the petrogenetic process. At present, the widely used methods of insitu analysis are HfO isotopes of zircon, Nd isotope of apatite and titanite, and SrPb isotopes of apatite and plagioclase. On the basis of updated references and our recent work, this paper summarized the applications of insitu isotopic analysis to the study of the origin of granitoids, i.e., tracing the sources of magmas and petrogenetic processes, in order to promote the research on insitu analytical method and the study of granitoids in China. Related Articles | Metrics

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Early Mesozoic highpressure metamorphism within the Lhasa Block, Tibet and its implications for regional tectonics. CENG Lian-Sen LIU Jing GAO Li-E CHEN Fang-Yuan XIE Ke-Jia 2009, 16(2): 140-151.  Abstract ( 1773 )   PDF (3046KB) ( 991 )   The nearly eastwest trending SumdoJiaxing eclogite belt, ～200 km east of Lhasa, occurs within the traditional Late Paleozoic quartzite and carbonate units of the Lhasa block. This belt provides information that constrains how the Cimmerian subcontinent was assembled. The major and trace element data of bulkrock indicate that these eclogites have preserved an NMORB type geochemistry,which is also in consistency with their SrNd isotopic systematics. The pT estimations show that they experienced high pressure metamorphism at ～26 GPa and ～650 ℃. Garnetomphacitewhole rock SmNd isochron yields an age of (2390±35) Ma. This age represents the timing of the high pressure metamorphism that led to the formation of the Sumdo eclogite. These data show that the SumdoJiaxing oceanic block was subducted to a depth of ～75 km and underwent high pressure metamorphism at ～239 Ma. Such an early Mesozoic event of subduction of oceanic crust within the Lhasa Block suggests that (1) at least one oceanic basin existed concurrently with the PaleoTethys and (2) the Cimmerrian subcontinent was assembled by a number of smaller continental or oceanic blocks that were scattered within the PaleoTethyan Ocean. Related Articles | Metrics

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Early Cretaceous magma mixing in Ranwu Area of Eastern Gangdese, Tibet: Evidence from zircon SHRIMP U-Pb age and Hf isotopic composition LIU Min SHU Di-Cheng DIAO Zhi-Dan WANG Li-Quan MO Xuan-Hua ZHOU Chang-Yong 2009, 16(2): 152-160.  Abstract ( 2466 )   PDF (1463KB) ( 971 )   The petrogenesis of the extensive Early Cretaceous magmatism in Gangdese Belt and how the tectonic units correlate to the east have long been subjects of debateTo explore these issues, we performed zircon SHRIMP UPb dating and zircon Hf isotopic determination on a dioritic dike from the Ranwu Pluton in Eastern Gangdese, TibetZircons from a diorite sample yield a crystallization age of (1142±09) Ma, identical to the monzogranite of the Ranwu PlutonZircon Hf isotopic compositions of the diorite sample are heterogeneous with  εHf(t) values ranging from -42 to +49, corresponding to the Hf isotopic crustal model ages (TCDM) of 085144 GaThe dioritic sample has εNd(t) value of -47 with twostage model age (TDM2) of 129 Ga, within the range of the zircon Hf isotope model ageThe contemporaneous dioritic dike (and enclave) and the host monzogranite, along with the heterogeneous Hf isotopic compositions indicate the presence of an important magma mixing in Ranwu Area at ~115 MaThis finding, in combination with the Hf isotopic crustal model ages recently reported in other places in the Gangdese Belt, suggest that the Ranwu Area could be correlated with the Middle Gangdese Belt rather than the Northern Gangdese Belt as previously thought. Related Articles | Metrics

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Zircon U-Pb dating and geochemistry of clastic sedimentary rocks in the GongheHuashixia Area, Qinghai Province and their geological implications CHEN Yue-Long ZHOU Jian PI Qiao-Hui WANG Zhong LI Da-Feng 2009, 16(2): 161-174.  Abstract ( 1735 )   PDF (2501KB) ( 871 )   The Triassic clastic sedimentary rocks in the GongheHuashixia Area, Qinghai Province are classified as greywacke and arkose based on petrochemistryProvenance rocks formed in arc setting during the Paleozoic and were exhumed to surface by subsequent collision, which are mafic or its partial melting product, metamorphosed basement and/or its anatexis magma, as well as granitesAveraged Nd depleted mantle model age is 175 Ga, which is consistent with those of basements of the Qilian Mountains, the Qaidam, the Eastern Kunlun Orogens and the Yangtze CratonThe Nd depleted model age suggests that the blocks share common tectonic affinity to the GondwanaThe histogram and probability density distribution of zircon UPb ages show significant peaks of 400500 Ma, 250300 Ma plus a secondary peak of 7501 000 Ma, which indicate key tectonomagmatism episodes of the Paleozoic, the Early Mesozoic, and the Neoproterozoic in the Qaidam, the Eastern Kunlun, and the Qilian MountainsThe ages of greater than 1 000 to 2 700 Ma represent basement formation of the Qilian, the Qaidam and the Eastern Kunlun OrogensHf isotopic compositions of zircons show three dominant age ranges of 1725 Ga, 2836 Ga and 1017 Ga for accretion of provenance crustThe majority of zircons are mixing products of anatexis melts derived from NeoproterozoicPaleozoic mafic rocks and basement rocks of the Qilian Mountains, the Qaidam, and the Eastern Kunlun MountainsThe Late PaleozoicEarly Mesozoic zircons originated mainly from anatexis melts of Paleozoic juvenile crustContrasting histogram to that of Triassic clastic sedimentary rocks in the western Qinling Mountain suggests that their provenance material were not communicated owing to the barrier of the western Qinling MountainIn contrast to high reliefs of the Qaidam, the Qilian Mountains, and the Eastern Kunlun, the western Qinling Mountain was in low relief with little contribution to the Gonghe Basin during the Triassic period. Related Articles | Metrics

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Late Mesoproterozoic to Paleozoic tectonothermal events in the Eastern Segment of the Central Tianshan Tectonic Zone of Northwestern China: Constraints from SHRIMP zircon geochronology. LI Qiu-Gen LIU Shu-Wen SONG Biao WANG Pan-Bin CHEN You-Zhang 2009, 16(2): 175-184.  Abstract ( 2099 )   PDF (1549KB) ( 989 )   The Proterozoic Xingxingxia Complex is the oldest exposed unit in the Eastern Segment of the Central Tianshan Tectonic Zone (ESCTTZ), which consists mainly of amphibolites and various parametamorphic rocks, and was intruded by MesoNeoproterozoic and Palaeozoic granitoid gneisses. The SHRIMP UPb dating of detrital zircon from a schist sample of the Xingxingxia Complex in the ESCTTZ yielded three distinct ages of  ~1 800 Ma, 1 530 Ma and 1 200 Ma, suggesting that the sediments derived not only from Palaeoproterozoic and Early Mesoproterozoic precursors but also from Late Mesoproterozoic precursors. The minimum detrital zircon age of (1 189±65) Ma, which is consistent with the ca. 12 Ga islandarc magmatic activity, could provide a significant constraint on the maximum depositional age for these sediments. In addition, the zircons from the schist sample also give two ages of about 910 and 470 Ma, respectively. The former is interpreted as the age of metamorphism; the latter, which is identical, within error, to the emplacement age of the identified Palaeozoic granotoid gneiss sample, is attributed to the disturbance of the Palaeozoic tectonothermal event. The ages of magmatic (ca. 1 200 Ma) and metamorphic (ca. 910 Ma) events in the ESCTTZ are akin to the ages of geologic events reported elsewhere in South China, East Antarctica, South Australia and southwestern North America, which signifies that the ESCTTZ may have played a crucial role in the assembly of the supercontinent Rodinia. Related Articles | Metrics

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Progress  of multifractal filtering techniques and their applications in geochemical information extraction. CHENG Qiu-Meng ZHANG Sheng-Yuan ZUO Ren-An CHEN Zhi-Jun XIE Chu-Yun JIA Qiang-Lin XU De-Xi TAO Ling-Jing 2009, 16(2): 185-198.  Abstract ( 4666 )   PDF (2125KB) ( 6292 )   Delineation of geochemical anomalies is essential both in exploration geochemistry and environmental geochemistry Since the first attempt of using the concentrationarea (CA) multifractal method for separating geochemical anomaly from background, it has become an innovative field of exploration and environmental geochemistry and various fractal filtering techniques have been developed for decomposing overlapping geochemical anomalies from complex backgrounds This paper  reviews the state of the art of the research on distribution patterns of geochemical elements and the approaches to identify geochemical anomalies, and demonstrates that the multifractal model provides a general distribution type for geochemical elements The “concentrationarea (CA)” fractal model is a fundamental model for characterizing geochemical anomalies related to mineralization or environment pollution impact It also provides a base for fractal filtering in various domains such as Fourier domain, Eigen domain and Wash domain The fractal filtering methods developed in these domains have not only the general advantages of traditional statistical methods but also added attraction as they  deal with anisotropic scaling and generalized selfsimilarity From application point of view these methods can reduce the influence of the variable background and enhance the local anomalies The methods have been commonly applied in delineation of target areas for mineral exploration and in recognition of pollution patterns for environmental assessment Related Articles | Metrics

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The sources of oreforming substance of Carlintype gold deposit: A discussion based on the characteristics of regional stratigraphic geochemical evolution in “GoldTriangle” area of Yunnan, Guizhou, Guangxi Provinces. ZHOU Tu-Guo LIU Ji-Shun WANG Zuo-Hua OU Yang-Yu-Fei GAO Qi-Zhi LIU De-Li HUANG Yuan-Wei 2009, 16(2): 199-208.  Abstract ( 2442 )   PDF (2102KB) ( 826 )    This study selected the YunnanGuizhouGuangxi Region (E 103°110°,N 22°26°), an area of about 200,000 km2, as the study object to discuss the relationship between the regional stratigraphic geochemical characteristics and the metallogeny based on the stream sedimentary data from 34 map sheets (1:200,000 scale) We come to the following conclusions: (1) Compared with Southern China, there are geochemical blocks of arsenic, antimony, gold, mercury and other lowtemperature elements in this area, with deep derived gold, and high background value of arsenic, antimony and mercury The concomitance of gold with arsenic, antimony and mercury is both inevitable and fortuitous (2) The formation of the high background level of siderophile elements, oxides and mineralizer which are related to basic magmatic activities is the geochemical reflection of the extravasation accompanying the formation of the Youjiang rift valley, the FuningGuanling northsouth strike fault zone, the WenshanFuning trust nappe structure and especially the Emei mantle plume, arising from the magmatic eruption and turbidite volcaniclastic sedimentary geochemistry (3) The eruption of Permian Emeishan basalt in Southwest Guizhou resulted in the abrupt change of gold and a large number of siderophile elements in Permian and Triassic deposits The Youjiang rift valley began its activity at least in the Cambrian, from West Guangxi to Southwest Guizhou as time gone by (4) The source substance of Carlintype gold in “Golden Triangle” of Yunnan, Guizhou, Guangxi Area was related to the rift valley, Tethys and regional deep fault and the deposit of basic igneous rocks and pyroclastic turbidite accompanying the activity of the Emei mantle plume Related Articles | Metrics

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New ore prospecting methodologies based on risk analysis in commercial assessments and their applications. FANG Wei-Xuan GUO Yu-Gan 2009, 16(2): 209-226.  Abstract ( 2016 )   PDF (2581KB) ( 664 )    The new ore prospecting methodologies based on risk analysis in commercial ore exploration and assessments are to focus on ore prospecting in the vicinities and deep parts of metal mines and on the venture capital investment in commercial ore exploration and assessments. We have systemically reviewed the achievements in ore prospecting from the views of risk analysis and economic geology, and summed up the following methodologies that can be widely used in ore prospecting for metal mines: those are the patterns of oreforming and geochemical haloforming and the related predicating system of geologygeochemistry; the tectonic geochemistry; the balance sheets of explorationexploitation of orebody; the optimization of occurrences and anomalies in the scope study, such as mineralization probability of occurrences and anomalies; the extensive assessments and quantitative predication. The mineralgeochemistry and the sublithofacies and microlithofacies mapping of lithofacies may also be broadly applied for ore prospecting and predication but only after making some improvement. With the development of ore prospecting methodologies based on risk analysis in commercial ore prospecting and assessments, the demands of the drastically increasing tasks of commercial oreexploration overseas can be steadily met. Thereby the management of ore exploration and exploitation will be promoted in the future. Related Articles | Metrics

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PGE deposits in Bushveld Complex: The occurrence and origin of the platinumgroup minerals TAN Juan-Juan SHU Yong-Feng 2009, 16(2): 227-238.  Abstract ( 1633 )   PDF (2003KB) ( 816 )   Geology and mineralogy of two types of platinumgroup elements (PGE) mineralization in Bushveld Complex have been summarized, with special attention to the occurrence of the PGEbearing minerals. Hosting three quarters of the known PGE resources on Earth, Bushveld Complex is the largest repository of PGE in the world, having intruded the Kaapvaal craton in the Paleoproterozoic. The east and west limbs of the Complex are characterized by homogeneous layered mineralization, represented by Merensky Reef (MR), in which the PGE content is averagely continuous. Most PGE concentrates in the intercumulus PGEsulfide. In the north limb, however, the PGE mineralization developing in contact zone is referred to  Platreef (PR). The mineralization is discontinuous, and the characteristics of different deposits vary along the trend with the changes in footwall lithology. The PGE carriers are dominantly semimetal compounds such as arsenide, telluride and antimonide. In such case, PGE can be decoupled from sulfide and occurred in silicate minerals. Related experiments demonstrated that PGE would fractionate during magma crystallization, and the effect of sulfur in this process could be represented by Pt/Pd ratios. Pd is more vulnerable to oxidation and more likely to remobilize with hydrothermal fluids as shown by Pt/Ir ratios. Those factors have caused the differences of the PGE occurrences in Platreef and Merensky Reef. The magma could have reached sulfuroversaturation before emplacement; the change of pressure in magma chamber and the magma conduits played important roles in PGE concentration and deposition. Fluid may have modified the existed PGE assemblage.   Related Articles | Metrics

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Metallogenic model of the Dongsheng insitu leaching sandstonetype uranium deposit in the Ordos Basin. YANG Xiao-Yong LING Meng-Xing LAI Xiao-Dong 2009, 16(2): 239-249.  Abstract ( 2604 )   PDF (1859KB) ( 865 )   The in-situ leaching sandstonetype uranium deposit is one of the uranium deposits with important industrial values, and the main target of exploration in Chinese nuclear geologyWith the development of oil and natural gas exploration in the Ordos basin, a breakthrough in exploration of insitu leaching sandstonetype uranium deposit in the northern part of the basin has been achievedAfter a brief introduction to the metallogenic geological conditions of this type of uranium deposit in Ordos basin, we provide the temperature and salinity conditions as well as the isotopic geochemical parameters of the oreforming fluid, which are obtained by the comprehensive geochemical analysesThe hydrogen and oxygen isotopic analyses of fluid inclusions indicate that the fluid as the formation water was derived from the mixture of magmatic water and meteoric waterThe carbon and oxygen stable isotopic analyses of cements of Ubearing sandstones show that the genesis of carbonate cements was the mixtures of mantle carbon, organic carbon and sedimentary carbonThis information presents the evidence that the organic material did come into the oreforming process, which is of significance to the formation of insitu leaching sandstonetype uranium depositThe oreforming geochemical model for this type of uranium deposit has been establishedThe uranium oreforming processes include oxidizing and reducing processes, during which some elements are enriched and some are depleted, accompanied with the uranium migrationThis study is of significance for understanding the enrichment and sedimentation of uranium as well as for finding the similar types of uranium deposits in other related basins. Related Articles | Metrics

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A study of fluid inclusions from Beiya goldpolymetallic deposit in Western Yunnan. XIAO Xiao-Niu YU Hua-Hui MO Xuan-Hua YANG Gui-Lai LI Yong HUANG Hang-Kai 2009, 16(2): 250-261.  Abstract ( 2195 )   PDF (1866KB) ( 829 )   The Beiya goldpolymetallic deposit is one of the typical deposits related to the alkalirich intrusion of the Cenozoic period in western Yunnan. This paper studies the fluid inclusions from quartz vein, quartz porphyroblast of alkalirich porphyry and calcite vein in the mining area. We investigated their types, temperatures, salinities, densities, pressures, the analytical data of liquids and gases, and the results of Laser Raman Microprobe Analysis. Based on above study, we made further discussions on the characteristics and sources of fluids. The research shows that the ore forming fluids are of NaClH2O types; the homogenization temperatures range from 132 ℃ to 550 ℃(individual is more than 550 ℃); the salinities are in the range of 19%611% (NaCleq). There exist three types of fluids, namely, the high temperature and high salinity fluids; the mediumhigh temperature and high salinity fluids; the mediumlow temperature and low salinity fluids. The fluidinclusion observations and microthermometric data suggest that the high salinity fluids were not produced by aqueous fluid immiscibility or boiling; they were directly formed in the magma chamber owing to the evolution of intermediateacidic magma, or from a shallow crystallized melt at the final stage. The high salinity fluid inclusions containing daughter minerals especially chalcopyrite have been found in the blocks of Hongnitang and Nadaping, indicating that these inclusions were formed from magmatic fluids before the incursion of meteoric water and magmatic water. The evidences from this study imply that the alkalirich intrusion has the great potential for forming porphyry deposit and the further research should be concentrated on the porphyry type of goldcopper deposit in Beiya. Related Articles | Metrics

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The coupling mechanism of the evolution of chemical structure with the characteristics of gas of tectonic coals. JIANG Bei QIN Yong JU Yi-Wen HONG Ji-Lin LI Meng 2009, 16(2): 262-271.  Abstract ( 1988 )   PDF (1242KB) ( 868 )    Coal is a special kind of rock that is sensitive to stress and strainUnder different stressstrain environment and tectonic stress effect, the physical structure, chemical structure, characteristic of optical property, etcof coal will greatly be changed, and tectonic coal with different structural characteristics and types will be formedVitrinite reflectance changes regularly during the process of tectonic coal deformation, which is extensively applied to the quantitative analysis of coalfield structureThis is also confirmed by deformation experiments under high temperature and confining pressureIn order to further investigate the microscopic mechanism of the change of vitrinite optical fabric, Xray diffraction, paramagnetic resonance and nuclear magnetic resonance were used to study the chemical structure of different types of tectonic coal and experimentally deformed coals under high temperature and confining pressureResearch shows that there is a close internal relation between the evolution of tectonic coal chemical structure and the vitrinite reflectanceThe optical property anomaly of vitrinite reflectance is a concrete manifestation of chemical structure evolution of tectonic coal in physical optical propertyDifferent physical and chemical structure in different types of tectonic coal resulted in a great difference in the characteristics such as gas content, permeability, etcMylonitic coal developed area is a dangerous belt for gas outburst in coal mine because of its high gas content and low permeability which are determined by special physical and chemical structuresTherefore, we can evaluate and predict the enrichment of mine gas and outburst hazard through studying distribution laws of tectonic coalIt provides a new thought and method for research on mine gas disaster. Related Articles | Metrics

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Description of Cretaceous sedimentary sequence of the Yaojia Formation recovered by CCSDSKⅠs borehole in Songliao Basin: Lithostratigraphy, sedimentary facies and cyclic stratigraphy. CHENG Ri-Hui WANG Guo-Dong WANG Pu-Jun GAO Wei-Feng LIN Yan-An WANG Cheng-Shan ZHANG Shi-Gong HONG Qing-Yuan 2009, 16(2): 272-287.  Abstract ( 1753 )   PDF (3372KB) ( 695 )   The Yaojia Formation recovered by CCSDSKⅠs borehole (China Cretaceous Continental Scientific DrillingSongkeⅠthe south borehole) is 15767 m long and 9996% of cores recovery. The age of the Formation corresponds to a range from the Santonian to the early Campanian. The sequences and processes of lithologylithofacies and cyclic stratigraphy were revealed by a detailed core description. Eleven rock types and three kinds of sedimentary subfacies including shallow lake, deep lake and delta front were recognized from the drilling core. There are eleven sedimentary microfacieses including dolostone, argillaceous limestone, shallow lake turbidite, deep lake turbidite, subaqueous mouth bar, distal bar, sheet sandstone, subaqueous distributary bay, slump deposits, shallow lake mudstone and deep lake mudstone. The Yaojia Formation represents one hundred and fiftyone meterscale cycles (sixthorder cycle), fortyfive fifthorder cycles, nine fourthorder cycles and three thirdorder cycles. Meticulous depiction (centimeter level) of the whole Formation provides an approach to study its sedimentary process with high precision. The red beds with thickness of 43% in the Yaojia Formation, being one of fewer continental red beds depicted meticulously in the world, will become a standard potential formulation section for the studies of Cretaceous global oxygenenriched events. Related Articles | Metrics

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Description of Cretaceous sedimentary sequence of the second and third member of the Qingshankou Formation recovered by CCSDSKⅠs borehole in Songliao Basin: Lithostratigraphy, sedimentary facies and cyclic stratigraphy. WANG Pu-Jun GAO Wei-Feng CHENG Ri-Hui WANG Guo-Dong TUN He-Yong MO Xiao-Qiao YANG Gan-Sheng HONG Zhong-Xin 2009, 16(2): 288-313.  Abstract ( 2000 )   PDF (4976KB) ( 651 )   The second and third member of the Qingshankou Formation recovered by CCSDSKⅠs borehole (China Cretaceous Continental Scientific DrillingSongkeⅠthe south borehole) is 41561 m long and 100% of cores recovery. The age of the member corresponds approximately to the Coniacian. The sequence and process of lithologylithofacies and cyclic stratigraphy were revealed by a detailed core description. Twelve rock types and two kinds of sedimentary subfacies including deep lake and shallow lake were recognized from the drilling core of the second and third member of the Qingshankou Formation. Ten sedimentary microfacies are present, including dolostone, marl, limestone, oil shale, deep lake turbidite, volcanic ash, seismite, deep lake mudstone, shallow lake mudstone and shallow lake turbidite microfacies. The second and third member of the Qingshankou Formation represents four hundred and twentytwo meterscale cycles (sixthorder cycle), one hundred and thirty fifthorder cycles, twentyone fourthorder cycles and one thirdorder cycles. The special lithologies such as mudstone, seismite, dolostone, volcanic ash and so on are important to researches on source rocks and lacustrine event sediments. Related Articles | Metrics

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Description of Cretaceous sedimentary sequence of the first member of the Qingshankou Formation recovered by CCSDSKⅠs borehole in Songliao Basin: Lithostratigraphy, sedimentary facies and cyclic stratigraphy. GAO Wei-Feng WANG Pu-Jun CHENG Ri-Hui WANG Guo-Dong MO Xiao-Qiao TUN He-Yong WANG Shu-Hua 2009, 16(2): 314-323.  Abstract ( 1824 )   PDF (2691KB) ( 663 )   The first member of the Qingshankou Formation recovered by CCSDSKⅠs borehole (China Cretaceous Continental Scientific DrillingSongkeⅠthe south borehole) is 8141 m long and 100% of cores recovery. The age of the member corresponds approximately to the Turonian. The sequence and process of lithologylithofacies and cyclic stratigraphy were revealed by a detailed core description. Six rock types（mudstone, dolostone, marl, limestone, ostracode limestone and volcanic ash）comprise the sedimentary strata. Deposition occurred in a deep lake, including six sedimentary microfacies: dolostone, marl, limestone, deep lake turbidite,  deep lake mudstone  and volcanic ash microfacies. The first member of the Qingshankou Formation represents eightyone meterscale cycles (sixthorder cycle), twentyfive fifthorder cycles, six fourthorder cycles and two thirdorder cycles. The occurrence and detailed description of mudstone, dolostone and volcanic ash are of significance for the study of anoxic events, source rock development and the potential linkage between lakemarine depositional events. Related Articles | Metrics

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Description of Cretaceous sedimentary sequence of the Quantou Formation recovered by CCSDSKⅠs borehole in Songliao Basin: Lithostratigraphy, sedimentary facies and cyclic stratigraphy. WANG Guo-Dong CHENG Ri-Hui WANG Pu-Jun GAO Wei-Feng WANG Cheng-Shan LIN Yan-An HUANG Qing-Hua 2009, 16(2): 324-338.  Abstract ( 1631 )   PDF (3181KB) ( 578 )   The Quantou Formation recovered by CCSDSKⅠs borehole (China Cretaceous Continental Scientific DrillingSongkeⅠthe south borehole) is 13207 m long and 100% of cores recovery. The sequence and process of lithologylithofacies and cyclic stratigraphy revealed by detailed core description. Nine rock types and three kinds of sedimentary facies including meandering river, shallow lake and delta front were recognized from the drilling core, there are ten sedimentary microfacies which are point bar, natural levee, crevasse splay, crevasse channel, floodplain, flood lake, subaqueous mouth bar, subaqueous inter distributary bay, mudstone of still water and turbidite. The Quantou Formation represents seventysix meterscale cycles (sixthorder cycle), twentyfive fifthorder cycles, eight forthorder cycles and two thirdorder cycles. Meticulously depicted(centimeter Level) continental red beds of the third and the fourth members of Quantou Formation will be a potential formulation profile for the studies on Cretaceous global oxygenenriched events. The reservoir sandstones of the third and the fourth members were developed basinwide as an inevitable product before the Songliao Basin was depressed or sagged with a large scale. The period of the third and the fourth members of Quantou Formation was a stage between developments of the fault basin and the sag basin with a large scale. Related Articles | Metrics

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Numerical simulations of sequestration of CO2 in the deep water of the ocean. XU Yong-Fu JIANG Chao 2009, 16(2): 339-346.  Abstract ( 1414 )   PDF (1060KB) ( 812 )   With the recognition of the issue of potential global climate change caused by the continuing increase in atmospheric CO2，scientists are seeking for the method of how to retard rapidly increasing atmospheric CO2, while they are probing for the global carbon cycling. After discussing some possible approaches, this study emphasizes on exploring the effectiveness of sequestration of CO2 in the ocean as one of the options. A basinwide ocean general circulation model of the North Pacific is used to study the behaviour of the sequestered CO2. A location is chosen in the North Pacific, and CO2 is artificially injected into different depths. Simulated results show that the sequestration effectiveness increases with increasing injection depth. Overall, if the injection depth exceeds 1 500 m, the sequestered CO2 in the ocean maintains over 95% of the injected CO2 at the end of the 50 years of continuous injection. If the injection depth exceeds 2 000 m, the impact of further increase in injection depth on the sequestration effectiveness becomes small, and the difference in effectiveness is less than 1% after 50 years. Related Articles | Metrics

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A review of bodywave tomography and its applications to studying the crust and mantle structure in China. TIAN Wei DIAO Da-Feng LIU Cai TENG Ji-Wen 2009, 16(2): 347-360.  Abstract ( 1878 )   PDF (2150KB) ( 762 )   In this article, we review the development of seismic tomography theory in the past 30 years. We analyze the existing problems of this method and propose some ways to resolve them. Then we summarize and discuss the research results in China obtained by using seismic tomography in the following topics: structure heterogeneity of the crust and mantle; deep structural environment affecting the generation of large earthquakes; deep structure and origin of active volcanoes; seismic structure of the orogenic belts and the platecollision zones. The studies so far indicate that highresolution images of the Earths interior structure obtained by using seismic tomography have provided crucial scientific foundation for improving our understanding of the evolution of lithosphere, plate motion and interactions, as well as deep structural environment that controls the generation of large earthquake and the formation of active volcanoes. Related Articles | Metrics

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The flux of river active material flowing into the sea: Preliminary achievements. SUN Ban-Ban ZHOU Guo-Hua WEI Hua-Ling-Liu-Tie-Yuan CENG Dao-Meng 2009, 16(2): 361-368.  Abstract ( 1152 )   PDF (1113KB) ( 516 )   River is a bridge between terrene and ocean. It is very important to study the flux of river active material flowing into the sea for current ecological geochemical evaluation. We have chosen 35 major rivers flowing into the sea in Eastern China and collected the samples of suspended particulate matter (SPM), filtered water and bed mud both in dry seasons and wet periods. By analysing these samples and using the runoff data of these rivers, we calculated the annual flux of major heavy metals and nutritive elements flowing into the sea for each river and for total terrestrial rivers. Furthermore, we determined the proportion of the quantity of elements migrating to the sea in watersoluble form to that in SPM form. This study provides the reference data for the research on sealand interactions and for shallow water ecological geochemical evaluation. Related Articles | Metrics

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Application of environmental isotopes and tracer techniques to seismic subsurface fluids. LIU Yao-Wei LIN Hong-Wei-Wang-Bo 2009, 16(2): 369-377.  Abstract ( 1704 )   PDF (1142KB) ( 769 )   In recent years, with the progress of new observation techniques and related theories, the tracing technique of environmental isotopes can be used to identify the dynamic information of groundwater, which is associated with the earthquake gestation and occurrence In this study, the characteristics of stable isotopes including 2H, 18O as well as radioactive isotopes such as 3H, 14C, and the tracing techniques are investigated Especially, with the environmental isotopes, the activity rules of groundwater including the groundwater recharge,circulation depth of geothermal water, waterrock interaction and groundwater age are discussed in depth The study was carried out to analyze the effects of the groundwater on its response to the stressstrain changes and to the tectonic activities It is worthy to mention that the tracing technique of environmental isotopes can be applied to identifying the information of seismic subsurface fluid, determining the intensity of seismicity, discussing the role of fluid in earthquake gestation, and estimating the effect of earthquake reflection in borehole Related Articles | Metrics

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Testing for the Granger causality of the changes of the Earths rotation and global earthquakes of magnitude above 5.0. YANG Guo-An-DAN Dun 2009, 16(2): 378-383.  Abstract ( 1459 )   PDF (599KB) ( 586 )   Using the Length of the Day from the EOP C04 data provided by the International Earth Rotation and Reference Systems Service (IERS), and the time series data of the earthquakes whose magnitudes are 5.0 or more than 5.0 from 1973 to 2008 provided by the National Earthquake Information Center (NEIC), this paper gives an analysis of the Granger causality between the changes of the Earth`s rotation and the global earthquakes. Granger causality tests show that there is indeed a twodirectional causal relationship between the changes of the Earth rotation and the earthquakes: one direction is that the changes of the Earths rotation may trigger the earthquakes, and the other is that the earthquake may induce the changes of the Earth`s rotation. This testing result implies that there probably exists a much complex excitation mechanism between the Earth`s rotation and the earthquakes. Related Articles | Metrics

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Analysis of geochemical characteristics and formation age of geothermal fluid deposited in Beiyuan Jiayuan to Beijing Olympic Park Area. XIAO Wen-Jin LU Jiu-Ru LIU Qing-Xiao FENG Hui AN Dun-Xi HU Sheng-Yang HU Wei-Shi TUN He-Ai 2009, 16(2): 384-395.  Abstract ( 2225 )   PDF (2061KB) ( 1406 )    Beijing Olympic Park Area is a newly discovered geothermal resource area in Beijing. Based on the geochemistry, HO isotopes, tritium isotopes and 14C dating data of the geothermal fluid and combining the geothermal geology background, we have studied the characteristics and the formation mechanism of the geothermal fluid in this area. The major hydrochemical type of the geothermal fluid is the type of HCO-3SO2-4Cl-Na+, and the minor one is HCO-3NO-3Ca2+Mg2+ type. The geothermal fluid was not supplied by the meteoric water and the runoff of the geothermal water is controlled by the regional fault system. The geothermal water is a mixed type of geothermal water between original geothermal water and deep cold underground water, and the original geothermal water was formed in 2000030000 a B.P. This area holds a big potential for geothermal water supply. Related Articles | Metrics

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Discussion on the marine regression event during the EarlyMiddle Holocene in the Liaoning Coast. FANG Jing WU E-Fang LI Rui-Wu ZHOU Jiang KANG Ling-Ling CHAI Dui MA Nan 2009, 16(2): 396-403.  Abstract ( 1618 )   PDF (1493KB) ( 622 )   We have carried out the diatom analysis of the cores of hand drilling D65 in the central Dayanghe plain of the eastern Liaodong peninsula, and made the successive electric conductivity measurements on the cores of hand drilling B3 of Bachagou in Changxing island in the west of Liaodong peninsula and on the cores of hand drilling X11 and X21 and mechanical drilling X33 in the lowerreach of Liaohe plain. Based on these diatom analysis and conductivity measurements, we obtained the diatom mappings and electric conductivity mappings of the cores, respectively.  It is shown that there are  marine facies layers  over 6 meters in thickness throughout the plain and  indicated that the seawater had reached the coastal plain in the Holocene, and that the transgression of the seawater  had occupied the coast for a long period In addition, it is revealed that there are continental facies or marineterrigenous facies formation  widely deposited beneath the marine facies bed in the depth about 57 meters, which indicates that the widespread marine regression event had occurred during  the transgressive period in the Holocene It can be presumed that they were formed in the time span from the early Holocene to the middle Holocene (9 3008 000 cal. a B.P.) according to the known 14C age dating. Related Articles | Metrics