• Volume 88,Issue 5,2014 Table of Contents
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    • New Editor-in-Chief Professor Degan SHU and Message from the Editor-in-Chief

      2014, 88(5).

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      Abstract:

    • Associate Editors-in-Chief

      2014, 88(5).

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      Abstract:

    • An Early Carboniferous Flora of the Huadu Locality from South China: Its Taxonomic Composition, Paleophytogeographical Position and Paleoecological Interpretation

      2014, 88(5):1341-1351.

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      Abstract:The Huadu flora of Guangdong Province, South China contains the lepidodendrid Lepidodendron shanyangense Wu et He, its putative rhizophore Stigmaria cf. ficoides (Brongniart) Sternberg; sphenophyte s.l. Archaeocalamites scrobiculatus (Brongniart) Stur; bowmanitid Sphenophyllum tenerrimum (Ettingshausen) Stur; pteridophyll Sphenopteris sp. of uncertain taxonomic position; undetermined ferns gen. et sp. nov.; lyginopterid pteridosperm Rhodeopteridium hsianghsiangense (Sze) Zhang, Zhao et Wu, a trigonocarpoid pteridosperm represented by fronds and isolated pinnules of Paripteris gigantea (Sternberg) Gothan, male fructifications of Potoniea sp., and seeds of Trigonocarpus sp. Ecologically, the Early Carboniferous (Visean) Huadu vegetation was divided into two neighboring communities: (1) a near-shore hydrophilous “community A” with predominating Archaeocalamites and Rhodeopteridium; and (2) a wet forest “community B” with predominating shrubby trigonocarpalean pteridosperm Paripteris gigantea (Sternberg) Gothan and tall tree-like lepidodendrid Lepidodendron shanyangense Wu et He. The Huadu vegetation was physiognomically similar to present-day low-latitude mangrove forest.

    • The Phototropism of Jurassic Petrified Wood in North China Plate

      2014, 88(5):1352-1355.

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      Abstract:Trees on the side directly exposed to sunlight generally grow faster than on the opposite side, a phenomenon termed plant phototropism. There are in situ vertical trunks of silicified wood in the Xiadelongwan area of Yanqing County, north Beijing, where the first National Geologic Park of Petrified Wood of China has been built since 2002. A few trunks have well-preserved growth rings. One petrified stump from the formation shows a positive phototropism direction of SW230°. As compared with the modern normal growth stumps in Beijing plain area, which have a positive phototropism direction of SW210 ° ± 5°, the evidence of wood phototropism supports the conclusion of previous palaeomagnetic studies that the North China Plate has rotated clockwise since the Late Jurassic. The known petrified wood stumps in the Yanshan-Liaoning area are mainly found from the strata of 165–136 Ma, which corresponds to the main stage of the Yanshanian Movement.

    • Xinjiangoxylon Gen. Nov., a New Gymnosperm from the Latest Permian of China

      2014, 88(5):1356-1363.

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      Abstract:Following the greatest known end-Permian mass extinction plants have low diversity. Lycopsids and conifers dominated on land. A new gymnosperm Xinjiangoxylon gen. nov. is proposed based on a woody stem specimen collected from the Upper Permian (latest, Changhsingian) Upper Guodikeng Formation of the Taoshuyuan section, Turpan, Xinjiang Uygur Autonomous Region, Northwest China. The decorticated stem is characterized by a complex pith, endarch primary xylem and a thick secondary xylem cylinder. Numerous petrified woods were found in the Changhsingian at this section. However, there are rare wood fossils in the Early Triassic. The abrupt decrease of fossil woods worldwide relates to the crisis at the end of the Permian. Xinjiangoxylon turpanense gen et. sp. nov. appears to represents one gymnosperm that existed in the latest Permian.

    • Paliurus (Paliureae, Rhamnaceae) from the Miocene of East China and its Macrofossil-based Phylogenetic and Phytogeographical History

      2014, 88(5):1364-1377.

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      Abstract:The extant genus Paliurus Miller is divided into P. ramosissimus and P. spina-christi groups and is diagnostically characterized by distinctive orbicular-winged fruits with a trilocular (or often bilocular) ovary and basally triveined leaves with a subentire to serrate margin. Here, structurally preserved winged fruits and associated compressed leaves of Paliurus (Paliureae, Rhamnaceae) are reported from the Middle-Upper Miocene Shengxian Formation of Tiantai, Zhejiang, eastern China. The fruits can be identified as Paliurus microcarpa Xiang-Chuan Li sp. nov., the diagnostic characters of external morphology and anatomy of which differ from those of both extant and fossil generic members; the leaves can be designated as Paliurus sp. The species based on winged fruits, P. microcarpa, might represent an ancient intermediate link exclusively known across the P. ramosissimus and P. spina-christi groups, showing a closer affinity to the P. ramosissimus group based on the resemblant smaller fruits with a narrower wing, and to the P. spina-christi group based on the similar wing structure and texture, respectively. Morphological analyses of the present and previous fossil fruit records around the world indicate that diversification of Paliurus had begun in northern transpacific regions by the Late Eocene. The macrofossil records, i.e., fruits and leaves of Paliurus globally when projected on paleoenvironmental maps in view of changing continental positions through time (from Eocene to Miocene) display that the past distribution of the genus was much wider than the present and belongs to a tropical and warm temperate realm of the Northern Hemisphere. Therefore, the modern restricted disjunction in tropical and warm temperate regions of East Asia and South Europe (even eastwards West Asia) might represent glacial refugia for some of the generic ancient lineages to survive severe cold at least since the terminal Pliocene.

    • Skeletal Microstructures of the Chiton Ischnochiton hakodadensis and a Comparison with the Cambrian Halkieria

      2014, 88(5):1378-1387.

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      Abstract:Halkieria is an Early Cambrian fossil genus with proposed phylogenetic affinities ranging from stem group lophotrochozoan to stem-group aculiferan. Skeletal similarities are often cited as evidence in support of a mollusk interpretation for Halkieria and related Cambrian fossils. The skeletal microstructures of the polyplacophoran mollusk (chiton) Ischnochiton hakodadensis, which bears perinotum elements resembling sclerites of halkieriids and other coeloscleritophoran small shelly fossils (SSFs), were studied to evaluate the interpretations. There are both similarities and differences between chiton skeletal structures and halkieriid sclerites: 1) the head valve of I. hakodadensis and the dorsal shell of Halkieria evangelista share a similar pattern of fine concentric growth lines, but halkieriid dorsal shells lack other polyplacophoran valve characteristics, including V-shaped indentation, radiate ribs; 2) the arrangement of I. hakodadensis perinotum elements in three zones is somewhat similar to the arrangement pattern of halkieriid sclerites; 3) the inner perinotum scales of I. hakodadensis (~200 μm in diameter) have a base and a blade, remarkably similar in morphology to halkieriid palmate sclerites (~400 μm in diameter). However, I. hakodadensis perinotum scales are nearly solid whereas halkieriid sclerites are hollow. These observations add a microstructural dimension to the skeletal comparison between mollusks and halkeriids, and may prove to be useful in resolving the phylogenetic affinity of Halkieria and the Halwaxiidae.

    • New Bivalved Arthropods from the Cambrian (Series 3, Drumian Stage) of Western Hunan, South China

      2014, 88(5):1388-1396.

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      Abstract:We report two new three-dimensionally phosphatized microfossils, Cambrolongispina reticulata gen. et sp. nov. and Cambrolongispina glabra gen. et sp. nov., from the middle Cambrian (Series 3, Drumian Stage) at Wangcun, Yongshun County, western Hunan, South China. They are bivalved arthropods, with thin, pliable, originally chitinous or chitin-calcareous shields (c. 350–517 mm long). The shields are equipped with a pair of antero-dorsal spines. The spines are internally hollow, varying in length from 1/2 of to as long as the shield length in C. reticulata, and uniformly longer than the shield length in C. glabra. The spines of C. reticulata are ornamented with a longitudinal row of conical or blade-shaped denticles along the posterior edge. Cambrolongispina lacks marginal rims, valve lobation and sulci which are diagnostic of the Bradoriida sensu stricto. It also lacks a doublure/duplicature characteristic of phosphatocopids and some bradoriids. It could be related to the Monasteriidae (which may belong to Bradoriida sensu lato), both characterized by a pair of antero-dorsal spines. Cambrolongispina may have been meiofaunal detritus feeders that lived on or within sediments. The antero-dorsal spines may have been sensory organs to detect nearby predators. The posterior denticles on these spines might have facilitated the sensory function of the spines.

    • Fossils of Macaca mulatta from Tianyuan Cave, with Notes on Some Previously Unpublished Specimens of Macaca from Zhoukoudian Area

      2014, 88(5):1397-1408.

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      Abstract:The recently discovered macaque fossils, including isolated teeth and mandible fragments, from Tianyuan Cave and the juvenile maxilla from Wanglaopu Cave near Zhoukoudian can be identified as Macaca mulatta; they represent the first recognized occurrence of fossil M. mulatta in the far north of China. Some previously unearthed but still unpublished Macaca specimens were also studied, including a cranium and the associated mandible from CKT Loc.13A, a maxilla and a mandible from Loc.1, a mandible from Loc.4, and a maxilla from Loc.20, as well as a mandible with complete toothrow from Zhoukoudian but without locality details, all of them can be referred to M. robusta. The study shows M. robusta is more closely related to M. mulatta than to M. anderssoni. Zhoukoudian is the richest area of Macacina fossils in North China, totally 2 genera and 4 species were once recognized from 9 localities, namely, Procynocephalus wimani, M. cf. anderssoni, M. robusta and M. mulatta. The fossil records of Macacina in Zhoukoudian area were almost continuous through the Quaternary Period, and it's reasonable to assume that Zhoukoudian used to be an evolutionary center for macaques in North China. Therefore, the macaque population of M. mulatta once existed decades ago around Beijing probably originated from the Pleistocene ancestors in the local area, rather than being human-introduced as previously thought.

    • Study on the Metallogenetism of Sub-mantle Plume and Mantle Branches in the Gold Mineralization Concentration Area of Northwest Jiaodong Peninsula

      2014, 88(5):1409-1420.

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      Abstract:The northwest of Jiaodong peninsula is characterized by its greatest gold concentration area, enormous gold reserves and limited time interval (115±5Ma) of gold mineralization in China. Studies show that the east area of north China began its mantle plume evolution since the Yanshanian movement, and the Laiyang sub-mantle plume and its surrounding mantle branches such as those in Guojiadian, Aishan and Panshidian were formed in the mineralization concentration area of northwestern Jiaodong peninsula. With the development of mantle plume → sub-mantle plume → mantle branch → favorable expending structures, the deep-derived hydrothermal fluid moved up to the favorable places, such as brittle-ductile or ductile-brittle shearing zones, the internal and external contact zones of intrusions, dense fracturing zones and the contact zones between dikes and countryrocks, and concentrated into deposits. Then the gold mineralization concentration zones that are centralized on mantle branches were formed. This study takes Guojiadian mantle branch as an example to discuss their metallogenetism and conclude the metallogenetic mode.

    • Serpentinized Peridotites at the North Part of the Wadi Allaqi District (Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust

      2014, 88(5):1421-1436.

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      Abstract:The Neoproterozoic Allaqi-Heiani suture (800-700 Ma) in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc-arc suture in the Arabian-Nubian shield (ANS). The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi-Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals (Cr-spinel and olivine) and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc-carbonate and quartz-carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr-magnetite. The fresh chromian spinels have high Cr# (0.62 to 0.79), while Mg# shows wider variation (0.35–0.59). High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra-subduction zone setting. They can be produced by up to ~20%–22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rocks reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore-arc peridotites of a supra-subduction zone.

    • The Petrology, Geochemistry, and Petrogenesis of E-MORB-type Mafic Rocks from the Guomangco Ophiolitic Mélange, Tibet

      2014, 88(5):1437-1453.

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      Abstract:The Guomangco ophiolitic mélange is situated in the middle part of the Shiquanhe–Yongzhu–Jiali ophiolitic mélange belt (SYJMB) and possesses all the subunits of a typical Penrose-type ophiolite pseudostratigraphy. The study of the Guomangco ophiolitic mélange is very important for investigating the tectonic evolution of the SYJMB. The mafic rocks of this ophiolitic mélange mainly include diabases, sillite dikes, and basalts. Geochemical analysis shows that these dikes mostly have E-MORB major and trace element signatures; this is the first time that this has been observed in the SYJMB. The basalts have N-MORB and IAB affinities, and the mineral chemistry of harzburgites shows a composition similar to that of SSZ peridotites, indicating that the Guomangco ophiolitic mélange probably originated in a back-arc basin. The Guomangco back-arc basin opened in the Middle Jurassic, which was caused by southward subduction of the Neo-Tethys Ocean in central Tibet. The main spreading of this back-arc basin occurred during the Late Jurassic, and the basalts were formed during this time. With the development of the back-arc basin, the subducted slab gradually retreated, and new mantle convection occurred in the mantle wedge. The recycling may have caused the metasomatized mantle to undergo a high degree of partial melting and to generate E-MORBs in the Early Cretaceous. E-MORB-type dikes probably crystallized from melts produced by about 20%–30% partial melting of a spinel mantle source, which was metasomatized by melts from low-degree partial melting of the subducted slab.

    • Geochemistry and Zircon U-Pb Dating of Changshagou Adakite from the South Altyn UHPM Terrane: Evidence of the Partial Melting of the Lower Crust

      2014, 88(5):1454-1465.

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      Abstract:Changshagou adakite, an outcrop in the middle segment of the South Altyn Tagh ultra-high pressure metamorphism (UHPM) terrane, contains medium-K cal-alkaline and weakly peraluminous compositions (SiO2 = 66.79% to 68.65%, Al2O3 = 17.48% to 18.31%, K2O + Na2O = 6.32% to 6.88%, K2O/Na2O = 0.25 to 0.33, A/CNK = 1.01 to 1.06). This outcrop is also enriched with large ion lithophile elements but with depleted high-field strength elements (HFSE) showing clearly negative Nb, Ta, and Ti anomalies. REE distribution patterns show a positive anomaly of Eu (δEu = 1.15 to 1.31) and weakly enriched with LREE compared with HREE (LREE/HREE = 1.02 to 4.20). Experimental results and several characteristics, including relatively low Nb/Ta ratios (6.03 to 8.45) and high Sr, Sr/Y, (La/Yb)N and low Y and Yb, which indicate the presence of residual garnet and the absence of plagioclase in the source region, show that adakite may form at a pressure ranging from 1.2 GPa to 1.5 GPa and at a temperature of approximately 900°C. Low Cr, Ni, and Mg# values, trace element patterns, and SiO2–Mg# and SiO2–MgO diagrams indicate that rocks are formed by the partial melting of a thickened lower continental crust. LA-ICP-MS in situ U-Pb dating yields two group ages: 503.1 ± 1.7 Ma (core) and 453.1 ± 3.0 Ma (rim). The Th/U ratios of the core and the rim are 0.11 to 0.40 and 0.03 to 0.07, respectively. Considering the zircon CL image characteristics, Th/U ratios, and previous studies on regional UHPM rocks, adakite formed at 503.1 ± 1.7 Ma and underwent a tectothermal event as a result of the break-off of the Altyn deep subducted continental crust at 453.1 ± 3.0 Ma.

    • Hydrothermal Dolomite in the Upper Sinian (Upper Proterozoic) Dengying Formation, East Sichuan Basin, China

      2014, 88(5):1466-1487.

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      Abstract:Hydrothermal Dolomite (HTD) is present in the Upper Sinian (Upper Proterozoic) Dengying Formation, east Sichuan Basin, China. The strata are comprised by primary dolomite. The HTD has various textures, including zebra dolomite, subhorizontal sheet-like cavities filled by saddle dolomite and breccias cemented by saddle dolomites as well occur as a fill of veins and fractures. Also co-occur MVT type lead-zinc ores in the study area. The δ13C and δ18O isotopes of HTD in the Upper Sinian Dengying Formation are lighter than those of the host rocks, while 87Sr/86Sr is higher. The apparent difference in carbon, oxygen and strontium isotopes, especially the large difference in 87Sr/86Sr isotopes ratio indicate crystallization from hot basinal and/or hydrothermal fluids. Saddle dolomite was precipitated at temperatures of 270-320°C. The diagenetic parasequences of mineral assemblage deposited in the Dengying Formation are: (1) dolomite host rock →sphalerite-galena-barite-fluorite; (2) dolomite host rock →saddle dolomite →quartz; (3) dolomite host rock → saddle dolomite→bitumen; (4) dolomite host rock → saddle dolomite → barite. The mean chemical composition of the host dolomite matrix and HTD didn’t change much during hydrothermal process. The fluids forming the HTDs in the Dengying Formation were mixtures of freshwater from the unconformity at the top of Sinian, fluids from diagenetic compaction and hydrocarbon generation & expulsion from the Lower Cambrian Niutitang Formation mudstones or the Doushantuo Formation silty mudstones, and hydrothermal fluids from the basement. The hydrocarbon reservoirs associated with the HTD were mostly controlled by the basement faults and fractures and karsting processes at the unconformity separating Sinian and Cambrian strata. The hydrocarbon storage spaces of HTD included dissolved cavities and intercrystalline pores. Dissolution cavities are extensive at the top of Dengying Formation, up to about 46m below the unconformity between Sinian and Cambrian and were generated mainly during karstification. Hydrothermal alteration enhanced the reservoir property of the Dengying Formation dolomites with 3%-5% increase in porosity. No agreement has been reached why zebra dolomite occurs only in the Upper Sinian strata, which would indicate that HTD mineralization occurred during two different periods, each of them related to major extensional tectonic event. The early one related to the Xingkai taphrogenesis(Z2-?1)and the later one to the Emei taphrogenesis (D2-T2). But, all the data from saddle dolomite suggest that the predominant crystallization occurred during the latter event.

    • Biogenic Sedimentary Structures of the Yellow River Delta in China and Their Composition and Distribution Characters

      2014, 88(5):1488-1498.

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      Abstract:The biogenic sedimentary structures (i.e., the morphology and trace makers of burrows, tracks,trails and traces made by extant organisms) and their composition and distribution characters in different micro environments and sub environments of the Yellow River delta in China are described. Three ichnocoenosis can be recognized: (1) Steinichnus-like ichnocoenosis, includes F, Y-shaped traces, birds’ footprints on bedding plane, and Y, U-shaped burrows in intrastratal bedding, produced by Coleoptera (Heteroceridae), Orthoptera (Gryllotalpidae) and birds. It is majorly found at the delta plain point bar deposits, denoting the fresh water-related terrestrial environments. (2) Steinichnus-Psilonichnus-like ichnocoenosis, consitsis of Steinichnus-like traces on the bedding plane and Psilonichnus-like burrow which a vertical, irregularly J-, Y-, or U-shaped burrows, some of them with bulbous basal cells burrows in the intrastratal bedding, created by Coleoptera (Heteroceridae), Orthoptera (Gryllotalpidae) and crabs. It is observed in the delta plain abandoned distributary channels, and the delta front tidal creek and subaquous distributary channels, indicating the brackish water environment. (3) Palaeophycus-like ichnocoenosis, includes the round entrance burrows or with craters-shaped loop-protrusionsand and the parallel forked trails on the bedding plane, and the U, J or vertical shaped feeding burrows are in the intrastratal bedding, majorly produced by the clam (bivalve molluscs), gastropods and Nereis. It is present in the subaqueous interdistributary bay, reflecting the intertidal related environment.

    • Morphological Characteristics of Sand Waves in the Middle Taiwan Shoal Based on Multi-beam Data Analysis

      2014, 88(5):1499-1512.

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      Abstract:A DTM map of the study area in the Taiwan Shoal was drawn based on precise and high-density data acquired in a field survey by a multi-beam sounding system (R2Sonic2024). We identified sand waves in the study area at water depths of 13.89–49.12 m; the main sand waves had heights of 5–25 m, lengths of 0.1–2.0 km, and crest lines 0.1–6.5 km long. The spatial distribution of the sand waves on the seabed is dense in the north and sparse in the south and the directions range between 50°–80° and 90°–135°. Between the main sand waves, secondary sand waves develop with heights of 0.1–5.0 m and lengths of 10–100 m, which are difficult to detect by satellite remote sensing. By comparing the evolution structures of the secondary and main sand waves, we identified three evolution modes of the secondary sand waves: parallel, oblique, and divergent modes according to the relative crest directions. Suitable water depth, reciprocating current speeds between 40 and 100 cm/s, and abundant sediment supply create favorable conditions for the formation of linear sand waves. Comparing the DTM maps and profiles of the June 2012 and June 2013 surveys of the same area, we found that the shape and morphology of the sand waves remained mostly unchanged under normal hydrodynamic conditions.

    • Depositional and Diagenetic Controls on Sandstone Reservoirs with Low Porosity and Low Permeability in the Eastern Sulige Gas Field, China

      2014, 88(5):1513-1534.

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      Abstract:In order to determine the genesis and the factors that control the low-porosity and low-permeability sandstone reservoirs in the eastern Sulige Gas Field in the Ordos Basin, systematic studies on the sedimentary facies and diagenesis were conducted by means of analysis of cores, thin sections, fluid inclusions, X-ray diffraction, cathode luminescence and scanning electron microscope. It was found that the sand bodies of the major gas reservoirs in the Shan1 section (P1S1) and the He8 section (P2H8) were formed during the Permian as sedimentary facies such as braided-channel bars, braided-river channels and point bars of a meandering river. Four types of diagenetic facies developed subsequently: in order from the best to the poorest properties these are type A (weak compaction, early calcite cement-chlorite film facies), type B (moderate compaction, quartz overgrowth-feldspar corrosion-kaolinite filling facies), type C (strong compaction, late calcite cement-quartz corrosion facies) and type D (matrix filling and strong compaction facies). This diagenesis is undoubtedly the main reason for the poor reservoir properties of sandstone reservoirs, but the sedimentary facies are the underlying factors that greatly affect the diagenesis and thus the reservoir performance. Favorable diagenetic facies developed mainly in relatively small lithofacies such as braided-river channels, channel bars and point bars. The vertical distribution of the physical properties and the diagenetic facies of the reservoirs are related to the stratigraphic succession. Most of the sandstones between mudstones and thin beds of sandstone are unfavorable diagenetic facies. Analyses indicate that siliceous cementation can hardly be stopped by hydrocarbon filling. Authigenic chlorite could hardly protect the primary porosity. It not only occupies pore space, but also blocks pathways through sandstone reservoirs, so that it has significant influence on the permeability. Authigenic chlorite cannot be used as a marker for a specific sedimentary facies because it can be formed in different sedimentary facies, but it indicates high hydrodynamic conditions and presence of favorable reservoirs.

    • Carbon Isotope Features of the Sugetbrak Section in the Aksu?Wushi Area, Northwest China: Implications for the Precambrian/Cambrian Stratigraphic Correlations

      2014, 88(5):1535-1546.

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      Abstract:The upper Qigeblaq Formation (Fm) dolostones and the Yurtus Fm phosphatic cherts, black shales, limestones, and dolostones are widely distributed in the Precambrian/Cambrian transitional succession of the Aksu-Wushi area. Negative δ13C excursion above the Yurtus Fm/Qigeblaq Fm boundary was determined in this study. The pronounced negative carbon isotope excursion occurs in the phosphatic chert layers at the bottom of the Cambrian Yurtus Fm, below which the first appearance of the Asteridium- Heliosphaeridium-Comasphaeridium (AHC) acritarch assemblage zone. The δ13C curve of the lower part of the Yurtus Fm in the Aksu-Wushi area was found to be correlated with the early Cambrian δ13C curves of the Zhujiaqing Fm (Daibu Member), the lower part of the Yanjiahe Fm on the Yangtze Platform in China, the lower Tal Fm in India, the Sukharikha Fm in Siberia, and the upper part of the Tsagaan Oloom Fm in Mongolia through biostigraphy. The lower part of the Yurtus Fm in the Tarim Basin is at the Nemakit-Daldynian stage, and the Precambrian/Cambrian boundary of the Aksu-Wushi area may be located in the phosphatic chert unit which just below the first appearance AHC acritarch assemblage zone. The negative δ13C excursion (N1) across the Precambrian/ Cambrian boundary in the studied section may have resulted from oceanic overturning and sea level rise.

    • Cenozoic Environmental Changes in the Northern Qaidam Basin Inferred from n-alkane Records

      2014, 88(5):1547-1555.

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      Abstract:Cenozoic climatic and environmental changes in the arid Asian interior, and their possible relations with global climatic changes and the Tibetan Plateau uplift, have been intensively investigated and debated over past decades. Here we present 40-Myr (million years)-long n-alkane records from a continuous Cenozoic sediment sequence in the Dahonggou Section, Qaidam Basin, northern Tibetan Plateau, to infer environmental changes in the northern basin. A set of n-alkane indexes, including ACL, CPI and Paq, vary substantially and consistently throughout the records, which are interpreted to reflect relative contributions from terrestrial vascular plants vs. aquatic macrophytes, and thus indicate depositional environments. ACL values vary between 21 and 30; CPI values range from 1.0 to 8.0; and Paq values change from <0.1 to 0.8 over the past 40-Myr. We have roughly identified two periods, at 25.8–21.0 Ma (million years ago) and 13.0–17.5 Ma, with higher ACL and CPI and lower Paq values indicating predominant lacustrine environments. Lower ACL and CPI values, together with higher Paq values, occurred at >25.8 Ma, 17.5–21.0 Ma, and <13.0 Ma, corresponding to alluvial fan/river deltaic deposits and shallow lacustrine settings, consistent with the observed features in sedimentological facies. The inferred Cenozoic environmental changes in the northern Qaidam Basin appear to correspond to global climatic changes.

    • Depositional Environment of Es4u and Es3l Shales Based on Biomarkers from the Boxing Sag of Dongying Depression, East China

      2014, 88(5):1556-1564.

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      Abstract:The Boxing Sag is located in the southwest of Dongying Depression, southern Bohai Bay Basin of East China. It is one of the main petroliferous sags in the Dongying Depression, and has two major source rocks, namely the upper 4th Member (Es4u) and lower 3rd Member (Es3l) shales of Eocene Shahejie Formation, which are the new exploration targets in recent years. In this study, 16 core samples were collected from Es4u and Es3l shales in the Boxing Sag, and the saturate hydrocarbons were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), respectively. The results show that Es4u shale has obvious phytane and gammacerane predominance, higher concentration of tricyclic terpanes and regular steranes, and very low concentration of 4-methly steranes; Es3l shale has pristane predominance, lower concentration of tricyclic terpanes, gammacerane and regular steranes, and higher concentration of 4-methly steranes. The Es4u shale can be further divided into two types based on the distribution of n-alkanes in gas chromatograms: normal distribution and double peak pattern. The biomarker characteristics and sedimentary facies distribution show that Es4u shale was deposited in the saline-hypersaline semi-deep (Type A Es4u shale, sag center) to shallow (Type B Es4u shale, sag edge) lacustrine environments, Es3l shale was deposited in the freshwater-brackish semi-deep-deep lacustrine environments, and the former sedimentary facies maps of Es4u and Es3l in the Boxing Sag are further modified.

    • Discovery and Significance of Malan Loess on the Piedmont Plain in Pinggu District, Beijing

      2014, 88(5):1565-1578.

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      Abstract:The platforms on both sides of the Malangou River (a lateral ditch of the Qingshui River that is a tributary of the Yongding River) where Malan Village in Zhaitang Town of Mentougou District of Beijing is located are the place of China’s typical section of the Quaternary Malan loess. During the investigation in the eastern suburbs of Beijing City, the authors not only clarified 5 grades of terraces on the Pinggu piedmont plain, but also found a clayey silt section mixed with a small amount of alluvial-diluvial gravel layers at a height of 15–25 m above the river level near a Fishpond in Xinli Village of Nandule Town. Results of the study of grain size of the section document that the loess mostly is silty soil (0.05–0.005 mm), and that the grain size probability cumulative curves of the section are dominated by single-peak, coarse-grained segment I and coarse-grained segment II types, reflecting that its depositional environment is similar to eolian phase. Identification results of heavy minerals from the section show that their contents account for 0.01%–0.11%, averaging 0.04%. There are 24 kinds of heavy minerals, most of which are stable heavy minerals, and the clay minerals mostly are illite, which is consistent with the Malan loess on the Loess Plateau. The chemical composition data reflect that the source area of the loess is relatively arid. The six grade classification of sporopollen in the section further shows the subdivision of the history of alternating warm and humid phases in this geological period. The thermoluminescence dating results range from 21.0 ka to 59.2 ka, convincingly demonstrating that the section indeed consists of Malan loess. The above studies provide a new basis for overall understanding of the distribution of the Malan loess at the northeast margin of the North China Plain and its environment change in the Late Pleistocene.

    • Clay Mineralogy and its Paleoclimatic Significance of the Oligocene-Miocene Sediments in the Gerze Basin, Tibet

      2014, 88(5):1579-1591.

      Abstract (993) HTML (0) PDF 15.56 M (817) Comment (0) Favorites

      Abstract:This study collected the early Oligocene to middle Miocene sediments from the Gerze Basin of Tibet, and used X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) to discuss their clay mineralolgy, clay indices, better understand the clay mineralogy and its paleoclimatic significance. The results show that clay minerals of the Gerze Basin sediments are mainly composed of illite and chlorite, with minor amounts of smectite and kaolinite, and their relative content varies along the section. Variations of relative contents and clay indices suggest that the Gerze Basin has experienced three-stage evolution of paleoclimate: Ⅰ) high illite and chlorite contents, with fluctuant smectite and low (I+Ch)/(K+S) ratio, indicative of a dominant seasonal arid climate from the early Oligocene to late Oligocene; Ⅱ) higher illite and chlorite contents and larger (I+Ch)/(K+S) ratio but absence of kaolinite, indicating a colder and drier climate from the late Oligocene to early Miocene; Ⅲ) high illite and chlorite contents with fluctuant (I+Ch)/(K+S) ratios and occasional occurrence of kaolinite, suggesting that the climate became warmer and more humid compared with that of stage Ⅱ in the mid-Miocene. These conclusions were also reinforced by the clay morphology, which suggests that physical weathering dominated in stage Ⅱ, while relatively strong chemical weathering was dominant in stages Ⅰ and Ⅲ. Clay minerals of the sediments mainly consist of illite and chlorite, indicating that the source rock played a significant role in clay origin. It is inferred that global cooling and the enhancement of denudation and obstruction of northward moisture due to the uplift of the Qinghai-Tibet Plateau were responsible for the provenance of illite and chlorite under weak chemical weathering. Though the Qinghai-Tibet Plateau reached a certain elevation by the mid-Miocene, yet the mid-Miocene widespread warming might have largely impacted the Gerze climate.

    • Piezomagnetic In-situ Stress Monitoring and its Application in the Longmenshan Fault Zone

      2014, 88(5):1592-1602.

      Abstract (738) HTML (0) PDF 12.59 M (885) Comment (0) Favorites

      Abstract:The relative change of in-situ stress is an inevitable outcome of differential movement among the crust plates. Conversely, changes of in-situ stress can also lead to deformation and instability of crustal rock mass, trigger activity of faults, and induce earthquakes. Hence, monitoring real-time change of in-situ stress is of great significance. Piezomagnetic in-situ stress monitoring has good and longtime applications in large engineering constructions and geoscience study fields in China. In this paper, the new piezomagnetic in-situ stress monitoring system is introduced and it not only has overall improvements in measuring cell’s structure and property, stressing and orienting way, but also enhances integration and intelligence of control and data transmission system, in general, which greatly promotes installing efficiency of measuring probe and quality of monitoring data. This paper also discusses the responses of new piezomagnetic system in large earthquake events of in-situ stress monitoring station at Qiaoqi of Baoxing and Wenxian of Gansu. The monitoring data reflect adjustments and changes of tectonic stress field at the southwestern segment of and the northern area near the Longmenshan fault zone, which shows that the new system has a good performance and application prospect in the geoscience field. Data of the Qiaoqi stress-monitoring station manifest that the Lushan Earthquake did not release stress of the southwestern segment of the Longmenshan fault zone adequately and there still probably exists seismic risk in this region in the future. Combined with absolute in-situ stress measurement, carrying out long-term in-situ stress monitoring in typical tectonic position of important regions is of great importance for researchers to assess and study regional crust stability.

    • Why Terrestrial Stable Carbon-isotope Stratigraphy Works: a Review

      2014, 88(5):1603-1613.

      Abstract (873) HTML (0) PDF 15.50 M (871) Comment (0) Favorites

      Abstract:Carbon-isotope stratigraphy launched since the early technological development of carbon-isotope measurement in 1950s, however, the emergence and advance of terrestrial carbon-isotope stratigraphy took quite a long way. At early stage the exploration of carbon-isotope stratigraphy based on the marine biological shell carbonates was verified by repeatable carbon-isotope stratigraphic data, laboratory chemical experiments and the later laboratory foraminiferal culture experiments. The breakthrough for testifying the fundamentals of terrestrial carbon-isotope stratigraphy lies on the synchronous fluctuations between the carbon-isotope stratigraphic curves derived from marine biological shell carbonates and those derived from terrestrial C3 plants. The character that carbon-isotope stratigraphic curves can be globally synchronously correlated over the marine and terrestrial/atmospheric reservoir mainly excludes the potential biasing factors, such as diagenetic bias, carbon-isotope variations in intra/inter individual plant in same species or between species, ecological changes, changes in aridity, changes in source input and representative sampling. Therefore, the fundamentals of terrestrial carbon-isotope stratigraphy based on C3 plant successfully established. The terrestrial carbon-isotope stratigraphy can be used for global stratigraphic correlation, reconstructing the evolution of atmospheric CO2 and can further verify the published global carbon-cycle models. The terrestrial carbon-isotope stratigraphy based on the compound specific biomarkers and single-grained pollen may be a promising perspective in future.

    • China's Seawater Desalination Plants Produce Megatons Freshwater For Low Cost

      2014, 88(5):1614-1615.

      Abstract (619) HTML (0) PDF 6.54 M (865) Comment (0) Favorites

      Abstract:

    • World’s Third-Largest Molybdenum Deposit Discovered in Caosiyao Area, Xinghe County, Inner Mongolia

      2014, 88(5):1615-1616.

      Abstract (738) HTML (0) PDF 6.54 M (969) Comment (0) Favorites

      Abstract:

    • Chinese Bio-oxidation Gold Extraction Technology Reaches International Advanced Level

      2014, 88(5):1617-1617.

      Abstract (665) HTML (0) PDF 6.54 M (1030) Comment (0) Favorites

      Abstract:

    • Acta Geologica Sinica (English Edition) Calls For Open-dated Submission of Paleontological Papers

      2014, 88(5):1618-1618.

      Abstract (645) HTML (0) PDF 6.54 M (818) Comment (0) Favorites

      Abstract:

    • Acta Geologica Sinica (English Edition) Calls For Submission of Review Papers

      2014, 88(5):1619-1619.

      Abstract (623) HTML (0) PDF 6.54 M (907) Comment (0) Favorites

      Abstract:

Chief Editor:HOU Zengqian

Governing Body:China Association for Science and Technology

Organizer:Geological Society of China

start publication :1922

ISSN:ISSN 1000-9515

CN:CN 11-2001/P

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