• Volume 85,Issue 4,2011 Table of Contents
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    • A New Genus and Species of Damsel-Dragonfly (Odonata: Isophlebioidea: Campterophlebiidae) in the Middle Jurassic of Inner Mongolia, China

      2011, 85(4):733-738.

      Abstract (1526) HTML (0) PDF 3.74 M (57) Comment (0) Favorites

      Abstract:The campterophlebiid new genus and species Ctenogampsophlebia reni is described from the Middle Jurassic of Inner Mongolia, China. It shows close similarities with the Lower to Middle Jurassic genera Gampsophlebia, and Petrophlebia, with closed and short subdiscoidal cells, confirming the attribution of these two other genera to the Campterophlebiidae.

    • An Extraordinary Early Jurassic Planthopper from Hunan (China) Representing a New Family Qiyangiricaniidae fam. nov. (Hemiptera: Fulgoromorpha: Fulgoroidea)

      2011, 85(4):739-748.

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      Abstract:A new family of planthoppers Fulgoromorpha from the Lower Jurassic of southern China is described to comprise Qiyangiricania cesta Lin, 1986. The new family differs in venation pattern from the other Jurassic representatives of Fulgoroidea, presenting particular model of tegmen venation, not found among extinct and recent planthoppers. The Mesozoic stage of Fulgoroidea evolution is discussed. The extinct taxon Ricaniites fulgens (Brodie, 1845) from the Purbeck of United Kingdom is excluded from the Hemiptera.

    • New Pelecinid Wasps (Hymenoptera: Proctotrupoidea: Pelecinidae) from the Yixian Formation of Western Liaoning, China

      2011, 85(4):749-757.

      Abstract (1828) HTML (0) PDF 5.63 M (37) Comment (0) Favorites

      Abstract:Three well-preserved fossil Pelecinids from the Late Mesozoic Yixian Formation, Liaoning Province, China are described and assigned to two new species, Eopelecinus huangi sp. nov. and Eopelecinus tumidus sp. nov. in Eopelecinus Zhang, Rasnitsyn and Zhang, 2002. As of now, 17 species have been included in this genus, which is the most diverse in the Pelecinidae family. With new information and characters obtained from these new specimens, the diagnosis of Eopelecinus Zhang, Rasnitsyn and Zhang, 2002 is emended.

    • New Bivalved Arthropods from Mid-Cambrian Kaili Biota of Southeastern Guizhou, Southwest China

      2011, 85(4):758-764.

      Abstract (1486) HTML (0) PDF 5.17 M (37) Comment (0) Favorites

      Abstract:Bivalved arthropods are very important elements in Mid-Cambrian Kaili Biota. Three genera, Alicaris, Pseudoarctolepis, and Forfexicaris, are herein recorded for the first time, including three new species: Alicaris kailiensis sp. nov., Forfexicaris reticulata sp. nov., and Pseudoarctolepis semicircularis sp. nov., of which Alicaris kailiensis sp. nov. could be assigned to crustaceomorphs; the other two forms are grouped as proschizoramians. These forms provide important information about the distribution and species diversity of a poorly-known element of Cambrian fauna, and also bridge the biotic evolutionary gap between Early Cambrian Chengjiang Biota in Southwest China and Mid-Cambrian burgess shale biota in North America.

    • A New Zosterophyll Plant, Ramoferis gen. nov., from the Posongchong Formation of Lower Devonian (Pragian) of Southeastern Yunnan, China

      2011, 85(4):765-776.

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      Abstract:A new genus and species, Ramoferis amalia gen. et sp. nov., is described from the Early Devonian (Pragian) Posongchong Formation, Wenshan district of southeastern Yunnan, China. This plant has isodichotomous major axes, which also divide anisotomously distally to produce closely spaced lateral branches, often within fertile regions. The stalked round to reniform sporangia, borne laterally and spirally over several levels of branches, are distantly to moderately spaced or aggregated into distinct spikes. The stalks increase in width from the base to the sporangial junction resulting in a gradual transition between sporangium and stalk. Comparison with known zosterophylls shows that this plant is most similar to the genera Zosterophyllum and Wenshania, differing in the character combinations of sporangial shape, sporangium/stalk junction, stalk dimensions and orientation, and especially in both sterile and fertile branchlets being borne within the fertile zone. In addition, the observation and comparison indicate distinct variety in structure of sporangial border and suggest that the two-layered sporangium wall characterized by outer anticlinal layer and inner periclinal layer might represent potential synapomorphies, while the different dehiscence mechanism is an autapomorphy for each taxon in zosterophylls.

    • Microbiostratigraphy of Kazhdumi Formation in the Northwestern Shiraz (Southwest Iran) on the Basis of Foraminifera and Calcareous Algae

      2011, 85(4):777-783.

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      Abstract:The middle Cretaceous Kazhdumi Formation, with a thickness of 222 m, belongs to the Bangestan Group and occurs in the Zagros folded zone in southwest Iran. The lower boundary with the Dariyan Formation is disconformable, which is recognized by iron oxides and glauconite. The recognized microfossils are Valvulammina sp., Scandonea sp., Daxia cenomana, Choffatela sp., Pseudolituonella reicheli and calcareous algae-Lithocodium aggregatum (which belongs to the Sarvak Formation), representing the beginning of Cenomanian. Other microfossils are: Ammobaculites goodlandensis, Marsonella trochus, Hemicyclammina sigali, Praechrysalidina infracretacea, Orbitolina gr. concava, Orbitolina (conicorbitolina) conica, Orbitolina subconcava, Salpingoporella sp., Trinocladus tripolitanus, Trinocladus sp., Permocalculus irenae and Dissocladella deserta. These microfossils can be classified into five assemblage zones.

    • Distinguishing and Correlating Multiple Phases of Metamorphism across Multiply Deformed Regions Using the Axes of Inclusion Trails in Porphyroblasts

      2011, 85(4):784-791.

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      Abstract:Successions of FIAs (foliation inflection/intersection axes preserved within porphyroblasts) provide a relative time scale for deformation and metamorphism. In-situ dating of monazite grains preserved as inclusions within garnet and staurolite porphyroblasts within the foliations defining each FIA from such successions provides a rigorous approach to grouping ages that formed over extended periods of deformation and metamorphism. Matching age and FIA progressions confirms the suitability of this approach plus provides access to lengthy histories that cannot otherwise be determined. Tectonism in the Big Thompson region of the Colorado Rocky Mountains, USA began about a SW-NE trending axis defined by FIA set 1 at around 1761±13 Ma. Subsequent periods of tectonism occurred around 1712±25 and 1672±21 Ma about W-E and NW-SE trending FIAs 2 and 3, respectively. Tectonism in the Balcooma Metamorphic Group NW of Greenvale in NE Queensland, Australia began around 470 Ma with the growth of garnet porphyroblasts about a W-E trending axis defined by FIA set 1. No monazite grains were preserved as inclusions in this mineral phase but they were in subsequently grown staurolite. Tectonism then occurred around 443.2±3.8, 424±4 and 408.9 ±8.9 Ma about NNW-SSE, SSW-NNE and W-E trending FIAs 2, 3 and 4, respectively. This test of a FIA based approach to monazite dating in tectonic regimes in different parts of the world and with dramatically different ages suggests it can be used in all orogens containing porphyroblasts preserving inclusion trails.

    • New Jurassic Paleomagnetic Results from Southeastern China and Their Geological Implication

      2011, 85(4):792-800.

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      Abstract:A paleomagnetic study was carried out on late Jurassic sediments in the Nanjing area. Stepwise thermal demagnetization was used to isolate the characteristic higher temperature component (HTC) (D=354.0°, I=48.5°, a95=7.8°), which passes the reversal test. A 24.7±8.7°counter-clockwise rotation relative to the Sichuan area is detected through comparing this new pole (84.4°N, 7.0°E, A95=7.7°) with other coeval poles reported from South China. This rotation was conducted by sinistral action of slip faults. These cases presenting in several areas of eastern China indicate that deformation of eastern China is under the effect of subduction from the Pacific Ocean plate. The difference on the paleolatitude of several areas across the Tan-Lu fault zone is calculated and suggests about at most 250 km offset distance after the later Jurassic.

    • Geochronology and Geochemistry of the Radiolarian Cherts of the Mada’er Area, Southwestern Tianshan: Implications for Depositional Environment

      2011, 85(4):801-813.

      Abstract (1738) HTML (0) PDF 7.82 M (34) Comment (0) Favorites

      Abstract:In the Southwestern Tianshan, the geologic ages of many strata and their depositional environments are still poorly constrained because of complex structures. The Mada’er area is located in the Kuokesaleling belt, Southwestern Tianshan. The cherts from the former Wupata’erkan Group contain abundant radiolarian fossils, including 10 species which are identified as late Devonian to early Carboniferous in age. Eleven chert samples have SiO2 contents ranging from 88.80 wt% to 93.28 wt%, and 2.02 wt% to 3.72 wt% for Al2O3. The SiO2/Al2O3 ratios of all samples vary from 23.84 to 46.11, much lower than those of the pure cherts (80–1400). These values suggest that the cherts contain high ratios of terrigenous materials. The Al2O3/(Al2O3+Fe2O3) ratios vary between 0.64 and 0.77, whereas V and Cu concentrations range from 10.92 ppm to 26.7 ppm and from 2.15 ppm to 34.1 ppm respectively. The Ti/V ratios vary from 25.53 to 44.93. The total REE concentrations of the cherts are between 30.78 ppm and 59.26 ppm, averaging 45.46 ppm. The (La/Ce)N ratios range from 0.81 to 1.12, and 0.88–1.33 for (La/Yb)N, averaging 1.09, which suggests a continental margin environment. Consequently, it is inferred that the cherts formed in a residual sea environment during the late Devonian to early Carboniferous time, which suggests that the collision between the Karakum-Tarim and Kazakhstan-Junggar plates did not occur at the time. In addition, the regional geological information indicates that the study area experienced a post-collision stage during the early Permian, and thus it is likely that the collision between the two plates took place in the late Carboniferous.

    • Spatial Distribution and Longitudinal Variation of Clay Minerals in the Central Indian Basin

      2011, 85(4):814-825.

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      Abstract:Grain size and clay mineral distribution up to 45 cm depth in the silty clay sediments from 26 box cores from 10° to 16° S along four longitudes (73.5°–76.5°E) were studied for understanding spatial variability in the Central Indian Basin (CIB). It was observed that the average sand content in the basin is 3.8%, which decreases systematically and longitudinally to 0.3% towards south. The average illite and chlorite major clay mineral abundance also decrease southwards along the four longitudes from 10°S, and show the limit of influence of the Ganges- Brahmaputra river’s supply up to 10° S. However, the average clay content increases from west to east in the basin, and southwards along 73.5°E and either side of the 76.5°E fracture zone (FZ), which strongly suggests the possibility of clay supply due to circulation of Antarctic Bottom Water (AABW) from the south through the FZ. The distribution of four clay minerals along 73° and 76.5° E FZ in the CIB shows dissimilar trends of increase and decrease, and indicate a mix environment in the basin. This study indicates that the FZ in the CIB has an important role in controlling the distribution of clay minerals.

    • Physical Properties, Morphology and Petrological Characteristics of Pumices from the Central Indian Ocean Basin

      2011, 85(4):826-839.

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      Abstract:About 400 pumice clasts collected from the Central Indian Ocean Basin (CIOB) were studied for their morphology and were classified based on their shape and size. A majority of the samples range between <1 cm and 36 cm and in the Zinggs shape diagram plot in the equant and oblate fields. The Corey Shape Factor for most of the samples is close to 0.7, which is common for volcaniclastic material. The physical properties such as density, specific gravity, void ratio, porosity, moisture content and degree of saturation, were determined for 30 pumice samples. Density varies from 0.21 to 0.74 g/cm3 specific gravity 1.84 to 3.27, void ratio 2.21 to 10.67, porosity 67% to 91%, moisture content during sinking 0.44 to 2.35 and degree of saturation varies from 26.5% to 86%. Binocular and electron microscopy studies reveal that 60% of the vesicles are elongated, 30% are spherical and 10% are fibrous. Petrography of the pumices exhibits vitrophyric texture with phenocrysts of feldspars and clinopyroxenes. X-ray diffractrogram and mineral analyses confirm plagioclase to be a major phase, while quartz and orthoclase are not uncommon. Todorokite is commonly present in the ferromanganese oxide coating present over some of the pumices. This paper also delves into some details concerning the controversial origin of the pumices and glass shards in the CIOB.

    • Sensitive High Resolution Ion Micro-Probe U-Pb Zircon Geochronology and Geochemistry of Mafic Rocks from the Pulan-Xiangquanhe Ophiolite, Tibet: Constraints on the Evolution of the Neo-tethys

      2011, 85(4):840-853.

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      Abstract:The Pulan-Xiangquanhe ophiolite in the western Yarlung Tsangpo suture zone of Tibet is investigated for its geochemistry, geochronology, and tectonic implications in detail. Sensitive high resolution ion micro-probe zircon U-Pb dating reveals that diabases in the ophiolite from the three locations of Xugugab, Mapam Yum Co and La’nga Co are dated at 122.3±2.5 Ma, 118.8±1.8 Ma and 120.5±1.9 Ma, respectively. These early Cretaceous mafic rocks have Na2O+K2O, rare earth element patterns, trace elemental spider diagram and other geochemical fingerprints of typical mature back-arc basin affinity. Therefore, the Pulan-Xiangquanhe ophiolite formed under a mature back-arc basin environment, which was a product of this intra-oceanic subduction system. A suprasubduction system could have existed in the southern margin of Eurasia, which involved both intra-oceanic and continent-ward subductions. Extension dominated the southern margin of the Eurasian continent during the early Cretaceous.

    • Ages of the Laocheng Granitoids and Crustal Growth in the South Qinling Tectonic Domain, Central China: Zircon U-Pb and Lu-Hf Isotopic Constraints

      2011, 85(4):854-869.

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      Abstract:The Laocheng granitoid pluton is located in the South Qinling tectonic domain of the Qinling orogenic belt, southern Shaanxi Province, and consists chiefly of quartz diorite, granodiorite and monzogranite. A LA-ICP-MS zircon U-Pb isotopic dating, in conjunction with cathodoluminescence images, reveals that the quartz diorite and granodiorite were emplaced from 220 Ma to 216 Ma, while the monzogranite was emplaced at ~210 Ma. In-situ zircon Hf isotopic analyses show that the εHf(t) values of the quartz diorite and granodiorite range from -8.1 to +1.3, and single-stage Hf model ages from 809 Ma to 1171 Ma, while the εHf(t) values of the monzogranite are -14.5 to +16.7 and single-stage Hf model ages from 189 Ma to 1424 Ma. These Hf isotopic features reveal that the quartz diorite, granodiorite and monzogranite were formed from the mixing of the magmas derived from partial melting of the depleted mantle and the lower continent crustal materials, and there were two stages of continental crust growth during the Neoproterozoic (~800 Ma) and Indosinian (~210 Ma) eras, respectively, in the south Qinling tectonic domain of the Qinling orogrnic belt, Central China.

    • Geochronology and Petrogenesis for the Protolith of Biotite Plagioclase Gneiss at Lianghe, Western Yunnan

      2011, 85(4):870-880.

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      Abstract:In this paper, we report an integrated study of U-Pb age and Hf isotope compositions of zircons from biotite plagioclase gneiss at Lianghe in western Yunnan. The zircons preserved inherited core and rim texture. Igneous zircon grains and rims yielded a weighted mean 206Pb/238U age of 120.4±1.7 Ma, their εHf (120 Ma) values were mainly negative ranging from –13.9 to –10.7, with Hf model ages between 1.9 Ga and 2.0 Ga, some zircons had positive εHf (120 Ma) values ranging from 0.2 to 2.1. The inherited cores showed the wide variations in the U-Pb age of 375–1315 Ma. One of them showed the εHf (506 Ma) value of –4.2, it was similar to the gray gneiss of old crust, which εHf (500 Ma) values were negative ranging from –4.5 to –3.3. Combining geological feature and geochemical data, we concluded that the protolith of biotite plagioclase gneiss was old crust-derived tonalitic magma during the early Cretaceous.

    • Characteristics of Hydrocarbon Accumulation in the Paleozoic Donghetang Formation in the Southwestern Tahe Area

      2011, 85(4):899-910.

      Abstract (1737) HTML (0) PDF 8.07 M (29) Comment (0) Favorites

      Abstract:The ancient structure characteristic, correlation of the oil and the hydrocarbon source rock characteristics, hydrocarbon migration trace, types and conditions of traps, migration passages and characteristic of hydrocarbon accumulation are researched in this paper. It is shown through the analysis that two main large tectonic activities after the Early Hercynian orogeny resulted in different tectonic patterns in the study area. Two main hydrocarbon infills occurred in the Donghetang Formation, the first occurred in the Early Hercynian resulting in the ancient hydrocarbon accumulation in the northern Tahe, the second infill was a large amount that occurred in places beneficial for hydrocarbon accumulation, such as structural traps and structural-stratigraphic traps formed in the Early Himalayan orogeny after migration along the faults through source rocks and other passages. Before the earlier period of the Himalayan orogeny, the petroleum mainly migrated to the north, whereas petroleum migrated to the south and southeast because of the structural reverse in the Himalayan orogeny, so the middle and later period of the Himalayan orogeny is the key period for hydrocarbon accumulation. The model of “oil generation formed early, hydrocarbon accumulation controlled by the faults through source rocks and structures formed late” is proposed. It is pointed out that the south of the research area is currently the beneficial district for hydrocarbon accumulation, which provides the basis for future petroleum exploration.

    • Kinetic Model of Gaseous Alkanes Formed from Coal in a Confined System and Its Application to Gas Filling History in Kuqa Depression, Tarim Basin, Northwest China

      2011, 85(4):911-922.

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      Abstract:Based on the pyrolysis products for the Jurassic low-mature coal under programmed temperature, and chemical and carbon isotopic compositions of natural gas from the Kuqa Depression, the genetic origin of natural gas was determined, and then a gas filling model was established, in combination with the geological background of the Kuqa Depression. The active energy of CH4, C2H6 and C3H8 was gotten after the data of pyrolysis gas products under different heating rates (2°C/h and 20°C/h) were fitted by the Gas Oil Ratio (GOR) Isotope Model soft. When the frequency factor (Af) was chosen as 1×1014, the active energy of CH4, C2H6 and C3H8 was 58?kcal/mol, 57?kcal/mol and 54?kcal/mol, respectively. The distributive ranges of the δ13C1,? δ13C2 and δ13C3 values for the pyrolysis gas products are –35.9‰ to –30.7‰, ?26.2‰ to ?21.3‰ and ?26.4‰ to ?22.7‰, respectively. All of the natural gases from the Kuqa Depression are dominated by hydrocarbon gases, with the high gas dryness (C1/C1?4) at the middle and northern parts of the depression and the low values at both east and west sides and the southern part. The carbon isotopes of methane and its homologs as a typical coal-type gas are enriched in 13C, and the distributive range of the δ13C1,? δ13C2 and ?δ13C3 value is ?32‰ to ?38‰, ?22‰ to ?24‰ and ?20‰ to ?22‰, respectively, with the carbon isotopes of gaseous alkanes being less negative with the carbon number. With the ethane being enriched in 13C the increasing tendency of the geological reserve of natural gas in the Kuqa Depression is observed. This observed change is consistent with the results of pyrolysate gas yield of coal as a potential gas source in the Kuqa Depression, suggesting natural gas was thermally derived from the humic organic matters and the carbon isotopes of gaseous alkanes would coarsely predict the geological reserve of gas in the Kuqa Depression. Through the simulation of kinetic processes of gas generation for the Jurassic coal in the Kuqa Depression, the gas in the Kela 2 gas field would get the threshold of gas expulsion after 27?Ma, be expelled out of source rocks as “pulse action”, and then filled in the gas reservoir. The peak gas-filling history took place during the past 2 Ma.

    • Geochemical Characterization and Origin of High-Sulfur, Heavy Oils in Jiyang Sub-Basin, East China

      2011, 85(4):923-931.

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      Abstract:High-sulfur, heavy petroleum is widely occurring in the Tertiary lacustrine Jiyang sub-basin, Bohai Bay Basin. They are differentiated into two families based on the bulk properties and biomarker compositions. Family 1 is characterized by high resins (40%–71%) and sulfur (2%–4%), and low wax (1%–6%), with n-alkanes removed by biodegradation, whereas family 2 is characterized by extremely abundant sulfur (3%–10%), and high asphaltenes (7%–31%) and wax (2%–19%), with no evidence of microbial attack. The oils of family 1 are distributed in the reservoir, lower than 1500 m throughout the sub-basin. Biomarker assemblages, such as low pristane/phytane ratios (<1 Pr/Ph) and a high abundance of carotane, gammacerane, and dinosterane, suggest that they are derived from the calcareous mudstones and shales among the stratified, saline Es4u unit, in addition to the in situ biodegradation-concentrated sulfur content. However, the oils of family 2 are identified only in the western Zhanhua and eastern Chezhen depressions, with a depth deeper than 1700 m. Physical properties, together with biomarker ratios, including even-numbered n-alkanes, <1 Pr/Ph, trace diasteranes, higher C35 homohopanes, and abundant dibenzothiophene series, with >1 dibenzothiophene/phenanthrene, indicate an origin from carbonate source rocks. The X-ray diffraction analysis showed that the carbonate source rock is limited in the Es4u unit of the Bonan sag, which is different from most other source rocks in the same horizon. It is suggested that the high-sulfur, heavy oils are generated at the early stage of the oil window. Bacterial sulfate reduction might be responsible for the occurrence of sulfur species in the high-sulfur, heavy oils, while heavy biodegradation will enhance sulfur concentrations.

    • Production Characteristics and the Control Factors of Surface Wells for Relieved Methane Drainage in the Huainan Mining Area

      2011, 85(4):932-941.

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      Abstract:Based on the production data of a large number of surface drainage wells in the Huainan mining area, the present study shows that four types of typical production characteristics for relieved methane wells are recognized, of which the stable type for production and gas concentration is the most dominate, as determined by a comprehensive study on the volume and concentration of drained gases, as well as the stress changes of rocks influenced by mining. Some influence factors for the productive differences of the drainage wells were also been discussed. The results indicate that protective coal-seam mining has a significant effect on overlying strata, which promotes the development of pores and fractures of coal reservoirs for methane desorption and migration; however, the production and the stability of drainage wells are affected by deformation and damage of the overlying strata. The second distribution of strata stress is caused by mining engineering, and if the stress load is larger than the carrying capacity of the extraction well, the gas production would be influenced by the drainage well that has been damaged by rock movement. Furthermore, the case damage occurs first in the weak, lithologic interface by its special mechanical properties. The stability of drainage wells and the production status are also influenced by the different drilling techniques, uneven distribution of gas concentration, and combination of gob gas and methane from the protected layer.

    • Palynological Analysis of Amber-Bearing Clay from the Lower Cretaceous of Central Lebanon

      2011, 85(4):942-949.

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      Abstract:An amber-bearing lignitic layer of sandy clay from the Lower Cretaceous of Central Lebanon (Mderej-Hammana) yielded a well-preserved, moderately variegated palynoflora, which origin is mixed between land plants and marine microflora. Its detailed analysis led to fulfill its inventory, to propose a paleoenvironmental reconstruction, and to draw the paleoclimate which prevailed over the region: an estuarian area under a rather humid, temperate climate; a variety of ferns grew near the shore-side and in the inward land. A tiny piece of amber containing angiospermous pollen grains of stratigraphical interest allows a precise dating. The marine microflora, poorly diversified, includes chitinous foraminifer linings and dinoflagellate cysts, among which Early Aptian guide taxa are present; their occurrence slightly narrows the stratigraphical range indicated by some palynological taxa which are related to land plants.

    • Paired Measurements of Foraminiferal d18O and Mg/Ca Ratios of Indian Monsoons Reconstructed from Holocene to Last Glacial Record

      2011, 85(4):950-956.

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      Abstract:The effect of seasonally reversing monsoons in the northern Indian Ocean is to impart significant changes in surface salinity (SS). Here, we report SS changes during the last 32 kyr in the Lakshadweep Sea (southeastern Arabian Sea) estimated from paired measurements of d18O and sea surface temperature (SST) using Globigerinoides sacculifer, an upper mixed layer dwelling foraminifera. The heaviest d18OG.sacculifer (–0.07±0.08‰) is recorded between 23 and 15 ka, which could be defined as the last glacial maximum (LGM). The d18OG.sacculifer shift between the LGM and Holocene is 2.07‰. The SST shows an overall warming of 2°C from the LGM to Holocene (28°C to 30°C). However, coldest SSTs are observed prior to LGM, i.e., ~27 ka. The SS was higher (~38 psu) throughout most of the recorded last glacial period (32.5–15 ka). This high salinity together with generally lower SSTs suggests a period of sustained weaker summer or stronger winter monsoons. The deglacial warming is associated with rapid reorganization of monsoons and is reflected in decreased salinity to a modern level of ~ 36.5 psu, within a period of ~5 kyr. This indicates intensification of summer monsoons during cold to warm climate transition.

    • A 2200-year Record of Seabird Population on Ganquan Island, South China Sea

      2011, 85(4):957-967.

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      Abstract:Geochemical characteristics of a 107 cm long sediment profile, collected from Ganquan Island, South China Sea, were analyzed. Based on concentrations of bio-elements (Cu, Zn, Cd, Ba, As, Se, P), 210Pb and AMS14C dating, we reconstructed seabird population of Ganquan Island over the past 2200 years. Seabirds inhabited this island more than 2200 years ago, and their population displayed remarkable fluctuations with two peaks around 2100–1850 yr BP and 900–300 yr BP, respectively. The seabird population change profile on Ganquan Island is similar to that on Dongdao Island over the past 1800 years. We examined the relationship between the seabird population and climate, and found it quite complicated. The seabird population did not reach the maximum during the Medical Warm Period (MWP) with relatively high average temperature; however, it remained near the peak value for about 600 years during the climatic transition period and the Little Ice Age (LIA), indicating that a relatively cool climate is favorable for seabirds on Ganquan Island.

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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