Abstract:Since 1988, great efforts and enthusiasm had been paid by applied geochemists in the implementation of global geochemical mapping through the International Geological Correlation Program’s Projects 259 and 360, and the Task Group on ‘Global Geochemical Baselines’ established by the International Union of Geological Sciences (IUGS), in collaboration with the International Association of GeoChemistry (IAGC). But how to use extremely low-density sampling to obtain a global picture of the distribution of most elements in the periodic table in a reasonably short time is still a great challenge faced by the applied geochemistry community. It will depend on the continuous development of new mapping concept, and the advisable and courageous innovation of methodology for searching other suitable sample media and sampling layout. Based on the encouragement results obtained from the representativeness study of delta sediments conducted at the mouth of Yangtze River, and at the mouths of its four major tributary, it is expected to broadly apply the geochemical fractal self-similarity nature to main rivers and their estuaries with catchments up to hundreds of thousands or over a million square kilometers in the world. With this new mapping concept, a new outlines of a Global Geochemical Mapping Program was advanced and the establishment of an International Research Center of Global Geochemical Mapping was also suggested to facilitate the programs implementations.

Abstract:A titanosauriform dinosaur: Fukuititan nipponensis gen. et sp. nov. is erected based on the incomplete skeleton. It is characterized by elongated asymmetric tooth crown with a weak or absent labial groove and without lingual concavity; stalk-like epipophysis of cervical vertebra; the transverse width of the proximal end of the humerus approximately 32% of the humerus length; metacarpal longer, approximately 48% of the radius and the distal end of the ischia slightly expanded. It represents the first relatively complete titanosauriform skeleton found from Japan. The discovery of Fukuititan indicates that the diversity and geographical distribution of Titanosauriformes are much higher than the previous thought.

Abstract:Epaxial tendons play an important role in the study of the musculoskeletal system and locomotory style of dinosaurs. Although the ossified epaxial tendon lattice is fairly well known in Iguanodontoidea, only recently has knowledge of this complex been extended to ceratopsians. This study concerns the gross morphology and microstructure of the tendon lattice in Psittacosaurus, a basal ceratopsian. As in the neoceratopsian Chasmosaurus, the ossified tendons of Psittacosaurus form a three-layered, lattice-like structure. The microstructure of the tendons in large psittacosaur individuals retains an early stage of ossification, as in juvenile birds and nestling hadrosaurs, suggesting a slow developmental rate of ossification of the tendons in psittacosaur ontogeny. Comparative study indicates that a lattice-like arrangement of three-layered epaxial tendons is widely distributed in Cerapoda. This pattern also extends to Ankylosauria, implying a similar pattern of the epaxial muscles through the ornithischian clade. In addition, comparison with crocodiles implies that the different morphology of ossified tendons in dinosaurs may be associated with adaptive aspects of their paleobiology, not simply a side effect of skeletal ossification. In contrast to the short tendons in quadrupedal Chasmosaurus and Protoceratops, the elongated tendons in Psittacosaurus may be related to the bipedal locomotion characteristic of this taxon.

Abstract:Recent discoveries of basal birds have greatly improved our understanding of early bird evolution, yet the evolution of several important features such as cranial kinesis and arboreality remain debated. A new sapeornithid bird, Shenshiornis primita gen. et sp. nov., based on an articulated skeleton from the Early Cretaceous Jehol Group of western Liaoning, China, sheds new light on these issues. Shenshiornis possesses a skull as primitive as or even more primitive than that of Archaeopteryx and hind limbs modified for an improved arboreal capability. A cladistic analysis shows that: 1) presence of a diapsid skull is a plesiomorphy of the Aves and a kinetic skull evolved incrementally later in avian evolution; and 2) cursorial capability significantly weakens at the base of the Pygostylia due to a change in locomotor system.

Abstract:The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate succession. In this succession, several lithofacies units, that is, the subtidal stromatolitic biostrome, the thrombolitic bioherm, tidal-flat micritic dolomite and lagoon dolomitic shale, make up many meter-scale cycles of the peritidal carbonate type that have been nominated as the Wumishan cycles. Importantly, many microdigital stromatolites make up the stromatolitic biostrome unit of the Wumishan cycles in the lower part of the Wumishan Formation. These microdigital stromatolites have been grouped as a stromatolitic assemblage by paleontologists, that is, “Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris” assemblage. These microdigital stromatolites had also been interpreted as the aragonite (tufa) sea-floor precipitates by sedimentologists, and has further been thought as the special products of the transitional period from the sea-floor aragonite precipitates of the Archean to the clastic and muddy carbonates of the Neoproterozoic. Although there are some restrictions for the stratigraphic meaning of the concept of the stromatolitic assemblage, detailed studies on classification by paleontologists provide an important clue to understand the sedimentological meaning of the microdigital stromatolites. Furthermore, an important and obvious horizon for the end of the microdigital stromatolites was recorded in the Mesoproterozoic Wumishan Formation at the Jixian section, which provides useful information to understand the stromatolite decline occurred at c.1250 Ma and the evolving carbonate world of the Precambrian.

Abstract:A serial of “comb-like and trough-like” folds developed in eastern Sichuan, controlled by the multi-layer detachment folding, is different from the classical Jura-type structure in their development. The key factor resulting in the development of these structures is the occurrence of detachment layers in different parts of Neoprotozoic to Mesozoic stratigraphy of study area, which, from the bottom to the top, are the lower part of Banxi Group, Lower Cambrian (Niutitang Formation), Lower Silurian (Longmaxi Formation and Luoreping Formation), Upper Permian (Wujiaping Formation) and Lower Triassic (Daye Formation). On the basis of field survey combined with sand-box modeling, this study argued that the detachment layer of the lower part of Banxi Group controlled the development of the “comb-like” folds, and the lower part of Cambrian detachment layer controlled the development of “trough-like” folds. Because of several detachment layers occurring in the study area, the development of duplex structures different scales is an important deformation mechanism, and the duplexes are the important structures distinguished from the typical detachment folding structures. Due to these duplexes, the surface structures and structural highs may not be the structural highs in the depth. Meanwhile, the detachment layers are good channels for oil/gas migration benefiting the understanding of accumulation and migration of oil and gas.

Abstract:In the present study, we present the occurrence and emplacement of chromite ore deposits from two abandoned mines (Kankavali [Janoli] and Wagda) in the Sindhudurg district of Maharashtra, India. These ores, that occurred as lenses and are associated with metamorphic and ultrabasic rocks, consist of octahedral grains of chromite, while clinochlore is present between the interstices of these grains. The Kankavali (Janoli) and Wagda ores revealed a dominance of Cr2O3 followed by FeO and variable proportions of Al2O3, MgO, and SiO2. The former deposits have a slightly higher Cr2O3 (average 52 wt%) and FeO (~18 wt%) than those from Wagda (Cr2O3 ~50 wt%, FeO ~25 wt%). The similar Cr# values (0.73 for Kankavali [Janoli], 0.74 for Wagda) correspond to those reported for typical podiform-type chromite deposits. We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest–southeast trend. We postulate the continuation of the fold structure from Janoli to Wagda (~4.5 km apart) and the probable (sporadic) occurrence of chromite along this stretch. The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out.

Abstract:GRV 020175 is an Antarctic mesosiderite, containing about 43 vol% silicates and 57 vol% metal. Metal occurs in a variety of textures from irregular large masses, to veins penetrating silicates, and to matrix fine grains. The metallic portion contains kamacite, troilite and minor taenite. Terrestrial weathering is evident as partial replacement of the metal and troilite veins by Fe oxides. Silicate phases exhibit a porphyritic texture with pyroxene, plagioclase, minor silica and rare olivine phenocrysts embedded in a fine-grained groundmass. The matrix is ophitic and consists mainly of pyroxene and plagioclase grains. Some orthopyroxene phenocrysts occur as euhedral crystals with chemical zoning from a magnesian core to a ferroan overgrowth; others are characterized by many fine inclusions of plagioclase composition. Pigeonite has almost inverted to its orthopyroxene host with augite lamellae, enclosed by more magnesian rims. Olivine occurs as subhedral crystals, surrounded by a necklace of tiny chromite grains (about 2–3 μm). Plagioclase has a heterogeneous composition without zoning. Pyroxene geothermometry of GRV 020175 gives a peak metamorphic temperature (~1000oC) and a closure temperature (~875°C). Molar Fe/Mn ratios (19–32) of pyroxenes are consistent with mesosiderite pyroxenes (16–35) and most plagioclase compositions (An87.5–96.6) are within the range of mesosiderite plagioclase grains (An88–95). Olivine composition (Fo53.8) is only slightly lower than the range of olivine compositions in mesosiderites (Fo55–90). All petrographic characteristics and chemical compositions of GRV 020175 are consistent with those of mesosiderite and based on its matrix texture and relatively abundant plagioclase, it can be further classified as a type 3A mesosiderite. Mineralogical, petrological, and geochemical studies of GRV 020175 imply a complex formation history starting as rapid crystallization from a magma in a lava flow on the surface or as a shallow intrusion. Following primary igneous crystallization, the silicate underwent varying degrees of reheating. It was reheated to 1000°C, followed by rapid cooling to 875°C. Subsequently, metal mixed with silicate, during or after which, reduction of silicates occurred; the reducing agent is likely to have been sulfur. After redox reaction, the sample underwent thermal metamorphism, which produced the corona on the olivine, rims on the inverted pigeonite phenocrysts and overgrowths on the orthopyroxene phenocrysts, and homogenized matrix pyroxenes. Nevertheless, metamorphism was not extensive enough to completely reequilibrate the GRV 020175 materials.

Abstract:Considerable controversy exists over whether or not extensive glaciation occurred during the global Last Glacial Maximum (LGM) in the Larsemann Hills. In this study we use the in situ produced cosmogenic nuclide 10Be (half life 1.51 Ma) to provide minimum exposure ages for six bedrock samples and one erratic boulder in order to determine the last period of deglaciation in the Larsemann Hills and on the neighboring Bolingen Islands. Three bedrock samples taken from Friendship Mountain (the highest peak on the Mirror Peninsula, Larsemann Hills; ~2 km from the ice sheet) have minimum exposure ages ranging from 40.0 to 44.7 ka. The erratic boulder from Peak 106 (just at the edge of the ice sheet) has a younger minimum exposure age of only 8.8 ka. The minimum exposure ages for two bedrock samples from Blundell Peak (the highest peak on Stornes Peninsula, Larsemann Hills; ~2 km from the ice sheet) are about 17 and 18 ka. On the Bolingen Islands (southwest to the Larsemann Hills; ~10 km from the ice sheet), the minimum exposure age for one bedrock sample is similar to that at Friendship Mountain (i.e., 44 ka). Our results indicate that the bedrock exposure in the Larsemann Hills and on the neighboring Bolingen Islands commenced obviously before the global LGM (i.e., 20-22 ka), and the bedrock erosion rates at the Antarctic coast areas may be obviously higher than in the interior land.

Abstract:Neoproterozoic rifting-related mafic igneous rocks are widely distributed both in the northern and southern margins of the Tarim Block, NW China. Here we report the geochronology and systematic whole-rock geochemistry of the Neoproterozoic mafic dykes and basalts along the southern margin of Tarim. Our zircon U-Pb age, in combination with stratigraphic constraint on their emplacement ages, indicates that the mafic dykes were crystallized at ca. 802 Ma, and the basalt, possibly coeval with the ca.740 Ma volcanic rocks in Quruqtagh in the northern margin of Tarim. Elemental and Nd isotope geochemistry of the mafic dykes and basalts suggest that their primitive magma was derived from asthenospheric mantle (OIB-like) and lithospheric mantle respectively, with variable assimilation of crustal materials. Integrating the data supplied in the present study and that reported previously in the northern margin of Tarim, we recognize two types of mantle sources of the Neoproterozoic mafic igneous rocks in Tarim, namely the matasomatized subcontinental lithospheric mantle (SCLM) in the northern margin and the long-term enriched lithospheric mantle and asthenospheric mantle in the southern margin. A comprehensive synthesis of the Neoproterozoic igneous rocks throughout the Tarim Block led to the recognition of two major episodes of Neoproterozoic igneous activities at ca. 820–800 Ma and ca. 780–740 Ma, respectively. These two episodes of igneous activities were concurrent with those in many other Rodinian continents and were most likely related to mantle plume activities during the break-up of the Rodinia.

Abstract:The rocks form as amphibolite ± garnet ± epidote and orthogneisses in the Pan-African basement of the Bitlis Massif. The petrochemical data of the studied metamorphic rocks suggest different igneous protoliths ranging from calcalkaline basalt to andesite in composition. Petrochemically, the rocks can be classified as group 1 (low Zr and La) and group 2 (high Zr and La), all showing various enrichments in large ion lithophiles and light rare earth elements, and a depletion in high-field strength elements, suggestive of a destructive plate margin setting. The protoliths of the all samples might have formed mostly by the partial melting of an enriched source, possibly coupled with the fractional crystallization of plagioclase, apatite, and titaniferous magnetite ± olivine ± clinopyroxene ± amphibole in relation with subduction-related magmatism neighboring the Andean-type active margins of Gondwana. The group 2 samples could, however, be generated by a relatively lower degree of the partial melting of an inhomogeneous source with a preponderance of a high-level, fractional crystallization process in comparison to group 1. The protoliths of the samples were metamorphosed up to amphibolite facies conditions, which destroys original igneous texture and mineral assemblages. Geothermobarometric calculations show that the metamorphic rocks are finally equilibrated between 540 and 610°C and ~5 kbars, following a clockwise P-T-t path.

Abstract:The Huangshan granitic intrusion in Anhui province, SE China, is tectonically located at the southeastern boundary of the Yangtze Block. Based on the contact relation and the petrography, the Huangshan granitic intrusion can be divided into four stages, from early to late, medium-grained monzogranite, coarse-grained porphyric granite, fine-medium grained porphyric granite, and fine-coarse grained granite. All rocks from the Huangshan granitic intrusion display similar petrological and geochemical characteristics, i.e. relatively high SiO2 (>75%) and alkali (7.85%–8.59%), low CaO (<1%), high Fe-number (FeOT/(MgO+FeOT) =?0.93–0.97) and A/CNK (atomic Al/(Ca+Na+K)) =?1.04–1.19. They are also enriched in rare earth elements (REE, except for Eu, with a total REE contents ranging from 116 ppm to 421 ppm), high strength field elements such as Zr, Hf, Nb, but depleted in Ba, Sr and Ni. The 10?000×Ga/Al ratios are higher than 2.6, which are consistent with the A-type granitoids. Based on the classification diagrams proposed by Eby, the Huangshan granite can be classified into the A2 group, which is usually believed to be formed under an extensional tectonic setting. Their Nd isotopic compositions suggest that the primary magmas of the Huangshan granite are predominantly derived from the Proterozoic andesitic rocks in the region, and this conclusion is also supported by REE modeling. The systemic investigations on the geochemistry of the Huangshan granitic intrusion can provide significant implications for the understanding of the petrogenesis and the geodynamic regime of southeastern China during the Late-Mesozoic.

Abstract:The world-class Huize Pb-Zn deposits of Yunnan province, in southwestern China, located in the center of the Sichuan-Yunnan-Guizhou Pb-Zn polymetallic metallogenic province, has Pb+Zn reserves of more than 5 million tons at Pb+Zn grade of higher than 25% and contains abundant associated metals, such as Ag, Ge, Cd, and Ga. The deposits are hosted in the Lower Carboniferous carbonate strata and the Permian Emeishan basalts which distributed in the northern and southwestern parts of the orefield. Calcite is the only gangue mineral in the primary ores of the deposits and can be classified into three types, namely lumpy, patch and vein calcites in accordance with their occurrence. There is not intercalated contact between calcite and ore minerals and among the three types of calcite, indicating that they are the same ore-forming age with different stages and its forming sequence is from lumpy to patch to vein calcites. This paper presents the rare earth element (REE) and C-O isotopic compositions of calcites in the Huize Pb-Zn deposits. From lumpy to patch to vein calcites, REE contents decrease as LREE/HREE ?ratios increase. The chondrite-normalized REE patterns of the three types of calcites are characterized by LREE-rich shaped, in which the lumpy calcite shows (La)N < (Ce)N < (Pr)N ≈ (Nd)N with Eu/Eu* < 1, the patch calcite has (La)N < (Ce)N < (Pr)N ≈ (Nd)N with Eu/Eu* > 1, and the vein calcite displays (La)N > (Ce)N > (Pr)N > (Nd)N with Eu/Eu* > 1. The REE geochemistry of the three types of calcite is different from those of the strata of various age and Permian Emeishan basalt exposed in the orefield. The δ13CPDB and δ18OSMOW values of the three types of calcites vary from ?3.5‰ to ?2.1‰ and 16.7‰ to 18.6‰, respectively, falling within a small field between primary mantle and marine carbonate in the δ13CPDB vs δ18OSMOW diagram. Various lines of evidence demonstrate that the three types of calcites in the deposits are produced from the same source with different stages. The ore-forming fluids of the deposits resulted from crustal-mantle mixing processes, in which the mantle-derived fluid components might be formed from degassing of mantle or/and magmatism of the Permian Emeishan basalts, and the crustal fluid was mainly provided by carbonate strata in the orefield. The ore-forming fluids in the deposits were homogenized before mineralization, and the ore-forming environment varied from relatively reducing to oxidizing.

Abstract:Jinshan gold deposit is located in northeastern Jiangxi, South China, which is related to the ductile shear zone. It has a gold reserve of more than 200 tons, with 80% of gold occurring in pyrite. The ΣREE of gold-bearing pyrite is as higher as 171.664 ppm on average, with relatively higher light rare earth elements (LREE; 159.556 ppm) and lower HREE (12.108 ppm). The ΣLREE/ΣHREE ratio is 12.612 and (La/Yb)N is 11.765. These indicate that pyrite is rich in LREE. The (La/Sm)N ratio is 3.758 and that of (Gd/Yb)N is 1.695. These are obvious LREE fractionations. The rare earth element (REE) distribution patterns show obvious Eu anomaly with average δEu values of 0.664, and δCe anomalies of 1.044. REE characteristics are similar to those of wall rocks (regional metamorphic rocks), but different from those of the Dexing granodiorite porphyry and Damaoshan biotite granite. These features indicate that the ore-forming materials in the Jinshan gold deposit derived from the wall rocks, and the ore-forming fluids derived from metamorphic water. The Co/Ni ratio (average value 0.38) of pyrite suggests that the Jinshan gold deposit formed under a medium–low temperature. It is inferred from the values of high-field strength elements, LREE, Hf/Sm, Nb/La, and Th/La of the pyrite that the ore-forming fluids of the Jinshan gold deposit derived from metamorphic water with Cl>F.

Abstract:Microbial mats are ecosystems that can control or induce the precipitation of calcium (Ca) carbonate on Earth through geological time. In the present study, we report on a novel accumulation of Ca, together with iron (Fe?), in a microbial mat collected from a slight acidic hot spring (pH=5.9) in south China. Combining an array of approaches, including environmental scanning electron microscopy, X-ray microanalysis, transmission electron microscopy, and selected area electron diffraction, we provide ultrastructral evidence for amorphous acicular aggregates containing Ca and Fe associated with cyanobacteria precipitating in the microbial mats. Cyanobacterial photosynthesis and exopolymeric organic matrixes are considered to be responsible for the precipitation of Ca. These amorphous acicular aggregates might imply the early stage of calcification occurring in microbial mats. Ca and Fe coprecipitation indicates another potential important way of inorganic element precipitation in hot spring microbial mats. Our results provide insight into the possible mechanism of cyanobacterial calcification and microfossil preservation in slight acidic hot spring environments.

Abstract:Kailu Basin in which the Western Lujiapu Depression is located is a typical continental rift basin. Biomarker parameters of the oils indicate that depositional facies and environments vary between the Bao 1 and Bao 14 fault blocks with a higher saline environment in the Bao 1 fault block, but such difference has no significant impact on carbazole abundance and distribution. Maturity and migration distance are the main controls on carbazole abundance and distribution in the Western Lujiapu Depression. The commonly used migration indices, such as ratios of nitrogen shield isomers to nitrogen exposed isomers (1-/4-methylcarbazole ratio, 1,8-/2,4-dimethylcarbazole (DMC) ratio and half-shield/exposed-DMC ratio), absolute concentrations of alkylated carbazoles and BC ratio (= benzo[a]carbazole/ (benzo[a]carbazole + benzo[c]carbazole)) increase at the low mature range and decrease at a higher mature range with increasing maturity. At relatively low maturity stage (Rc<0.77%), maturation has reversal effects with migration on the ratios of nitrogen shield isomers to nitrogen exposed isomers, which may cover migration influence and makes these parameters fail to indicate migration effects. Valid migration indicators at this maturity stage are concentrations of alkylated carbazoles and BC ratios, which can provide ideal tools for migration direction assessment even within short migration distance. Maturity effects should be taken into account when carbazole compounds are applied to indicate migration direction, and at different maturity stages, these commonly used parameters have different validity in tracing migration direction. Coupled with our previous study in the Eastern Lujiapu Depression, a conceptual model of the variation of nitrogen migration indices can be established for terrestrial rifted basins, that is, strong fractionation lateral migration model through sandy beds, weak fractionation vertical migration model along faults, and maturity impacts on migration assessment.

Abstract:In order to study the accumulation mechanism of “barkinite”, eight Late Permian channel benches (approximately 15-cm across and 10-cm deep) were taken from the Jinshan Mine, Anhui Province, China. The samples were analyzed by microscopical and geochemical methods. The microscopical observations indicate that the occurrence modes of “barkinite” in this area are different from those in other areas of China. The ratios of structureless “barkinite” are much higher in the Jinshan Mine, probably due to the flow-water and marine influenced environments. Furthermore, vitrinite macerals also show a strong fluorescence. The vitrinite fluorescence characteristics have not been observed in the Permian “barkinite” coals from northern China. The composition and variation of minerals in the column section also showed that the swamps in the study area were seriously influenced by seawater in the early and late stage during the peat accumulation.