Simulation of double cold cores of the 35°N section in the Yellow Sea with a wave-tide-circulation coupled model

Based on the MASNUM wave-tide-circulation coupled numerical model, the temperature structure along 35°N in the Yellow Sea was simulated and compared with the observations. One of the notable features of the temperature structure along 35°N section is the double cold cores phenomena during spring and summer. The double cold cores refer to the two cold water centers located near 122°E and 125°E from the depth of 30m to bottom. The formation, maintenance and disappearance of the double cold cores are discussed. At least two reasons make the temperature in the center (near 123°E) of the section higher than that near the west and east shores in winter. One reason is that the water there is deeper than the west and east sides so its heat content is higher. The other is invasion of the warm water brought by the Yellow Sea Warm Current (YSWC) during winter. This temperature pattern of the lower layer (from 30m to bottom) is maintained through spring and summer when the upper layer (0 to 30m) is heated and strong thermocline is formed. Large zonal span of the 35°N section (about 600 km) makes the cold cores have more opportunity to survive. The double cold cores phenomena disappears in early autumn when the west cold core vanishes first with the dropping of the thermocline position. Supported by the National Basic Research Program of China (No. G1999043809) and the National Science Foundation of China (No. 49736190).     

泰安市地下水污染现状与成因分析

采用参数分级评分叠加型指数法对泰安市地下水污染现状进行的评价结果显示 ,泰安地下水已遭受严重污染。地下水污染以地下水中宏量组分、NO-3 、硬度、TDS的迅速上升高以及地下水遭受人为环境物质的污染为主要标志 ;地下水污染主要受地下水系统水文地质结构、纳污河流、污水灌溉及地下水开采控制和影响 ,地下水污染是人类活动影响的结果。     

Fatty Acid Composition Analyses of the DCMU Resistant Mutants of Nannochloropsis oculata (Eustigmatophyceae)

1　Introduction　Nannochloropsissp .areoneofpotentialsourcesofpolyunsaturatedfattyacids ,especiallytheeicosapen taentaenoicacid (EPA ,C2 0∶5 ) ,whichisimportantforbothanimalsandhumans .　Thefattyacidcompositionofthisalgaisaffectedbyvariousenvironmentalfactors ,suchaslightintensity(Sukeniketal.,1989;Sukeniketal.,1990 ) ,imply ingthatafactorinfluencingthephotosyntheticprocessmayaffectcellularfattyacidsynthesisandtheirmetabolism .AselectionprogramofincreasingcellularEPAcontenthasbeencarriedo…     

Biogenic silicate accumulation in sediments, Jiaozhou Bay

1 INTRODUCTION Silicate, or silicic acid (H4SiO4), is a very im- portant nutrient in the ocean. Unlike other major nu- trients such as phosphate and nitrate or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical req…     

松辽盆地嫩江组白云岩形成机理——以松科1井南孔为例

松科1井是中国大陆第一口以白垩系地层为主的全取心科学探井,由松科1井南孔和松科1井北孔两个钻孔组成.在松科1井南孔岩心精细描述的过程中发现嫩江组地层中发育层状白云岩和椭球状白云岩,共62层.白云岩结核垂向截面的透镜形状、结核内部上凸下凹两端收敛的层理特点以及在显微镜下观察到的白云石的雾心亮边结构和泥灰岩被局部交代产生的"豹斑状"白云石聚集均显示嫩江组白云岩是湖相泥灰岩在准同生期被交代的产物.白云岩的形成机制是在晚白垩世松辽盆地海侵背景下Mg2 在准同生期交代由浊积事件、介形虫灭绝事件所带来的泥灰岩沉积而成.     

Zircon U–Pb and Hf isotopic study of gneissic rocks from the Chinese Altai: Progressive accretionary history in the early to middle Palaeozoic

Gneissic rocks in the Chinese Altai Mountains have been interpreted as either Paleozoic metasedimentary rocks or Precambrian basement. This study reports geochemical and geochronological data for banded paragneisses and associated gneissic granitoids collected along a NE–SW traverse in the northwestern Chinese Altai. Petrological and geochemical data suggest that the protoliths of the banded gneisses were possibly immature sediments with significant volcanic input and that the gneissic granitoids were derived from I-type granites formed in a subduction environment. Three types of morphological features can be recognized in zircons from the banded gneisses and are interpreted to correlate with different sources. Zircons from five samples of banded paragneiss cluster predominantly between 466 and 528 Ma, some give Neoproterozoic ages, and a few yield discordant Paleoproterozoic to Archean ages. Zircon Hf isotopic compositions indicate that both juvenile/mantle and crust materials were involved in the generation of the source rocks from which these zircons were derived. In contrast, zircons occur ubiquitously as elongated euhedral prismatic crystals in the four samples of the gneissic granitoids, and define single populations for each sample with mean ages between 380 and 453 Ma. The general absence of Precambrian inheritance and positive zircon ?Hf values for these granitoids suggest insignificant crustal contribution to the generation of the precursor magmas. Our data can be interpreted in terms of a progressive accretionary history in early to middle Palaeozoic times, and the Chinese Altai may possibly represent a magmatic arc built on a continental margin dominated by Neoproterozoic rocks.     

Timing of UHP metamorphism in the Hong’an area,western Dabie Mountains,China: evidence from zircon U–Pb age,trace element and Hf isotope composition

The Hong’an area (western Dabie Mountains) is the westernmost terrane in the Qinling-Dabie-Sulu orogen that preserves UHP eclogites. The ages of the UHP metamorphism have not been well constrained, and thus hinder our understanding of the tectonic evolution of this area. LA-ICPMS U–Pb age, trace element and Hf isotope compositions of zircons of a granitic gneiss and an eclogite from the Xinxian UHP unit in the Hong’an area were analyzed to constrain the age of the UHP metamorphism. Most zircons are unzoned or show sector zoning. They have low trace element concentrations, without significant negative Eu anomalies. These metamorphic zircons can be further subdivided into two groups according to their U–Pb ages, and trace element and Lu–Hf isotope compositions. One group with an average age of 239 ± 2 Ma show relatively high and variable HREE contents (527 ≥ Lu_N ≥ 14) and ¹⁷⁶Lu/¹⁷⁷Hf ratios (0.00008–0.000931), indicating their growth prior to a great deal of garnet growth in the late stage of continental subduction. The other group yields an average age of 227 ± 2 Ma, and shows consistent low HREE contents and ¹⁷⁶Lu/¹⁷⁷Hf ratios, suggesting their growth with concurrent garnet crystallization and/or recrystallization. These two groups of age are taken as recording the time of prograde HP to UHP and retrograde UHP–HP stages, respectively. A few cores have high Th/U ratios, high trace element contents, and a clear negative Eu anomaly. These features support a magmatic origin of these zircon cores. The upper intercept ages of 771 ± 86 and 752 ± 70 Ma for the granitic gneiss and eclogite, respectively, indicate that their protoliths probably formed as a bimodal suite in rifting zones in the northern margin of the Yangtze Block. Young Hf model ages (T _DM1) of magmatic cores indicate juvenile (mantle-derived) materials were involved in their protolith formation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

金川镍铜矿床数学模型对深部矿化变化趋势的指示

按矿化特征将金川X矿区主矿体分为致密块状特富矿、海绵状富矿和浸染状贫矿.应用MicroMine软件对3类矿化体分别建立了数学模型,并应用距离平方反比法对模型单元块进行了镍、铜品位估值.通过分析和对比矿床数学模型900m至1300m不同水平剖面上的Ni、Cu品位及Ni/Cu比值的变化,得出在X矿区的中部西侧是一个Ni和Cu的矿化中心,并且向深部Cu的矿化强度高于Ni.     

碳酸盐岩裂缝与岩溶作用研究

从构造与非构造作用角度出发,突出研究断层对裂缝的控制作用、断裂与岩溶的关系和裂缝与岩溶之间的关系,揭示碳酸盐岩裂缝与岩溶的发育规律。研究表明：构造裂缝为岩溶发育提供岩溶作用进行的有利通道,非构造裂缝则可以加速溶蚀作用的进行,促进岩溶的发育;裂缝与岩溶之间的关系始终是相辅相成、相互促进的关系。     

气候变化对塔里木河来自天山的地表径流影响

塔里木河水资源主要来自天山南坡两条源流,选择西段阿克苏河和中段开都河-孔雀河作为研究区.1956-2003年研究河源山区气温呈持续升温且降水波动增加的趋势,其中1995-2003年升温强劲,升温速率高出48 a期间平均的3倍以上;降水自1986年后持续增加,20世纪90年代较80年代增幅达18%,并显示出河源山区湿岛向塔里木盆地扩展.因高山缺少气象观测,出山径流过程变化可以综合反映中高山带的气候变化.塔里木河来自天山的地表径流在1986-2003年间持续增长,以冰川融水补给为主的库玛拉克河,1994年以来年径流量增加已在前期平均值基础上提升了一个台阶;开都河以降水径流补给为主,1986-2002年出现了观测记录以来的丰水期,并使1986年后博斯腾湖水位快速上升,恢复到1958年记录的最高水位以上.两河年径流变化趋势基本相似,但也显示有西、中段的气候变化局部差异,出现丰枯水期的不一致;然而,在近16 a升温过程中,年径流增长幅度和快慢相近.