Early Cambrian oceanic plagiogranite in the Silvretta Nappe,eastern Alps: geochemical,zircon U-Pb and Rb-Sr data from garnet-hornblende-plagioclase gneisses

 Garnet–hornblende–plagioclase gneisses rich in incompatible elements occur in the crystalline basement of the Austro-Alpine Silvretta nappe and are associated with clinopyroxene norites and harzburgite cumulates. It is proposed here that the gneisses were formerly oceanic plagiogranites. An ε_{Nd( 530 )} value of +5.6 for the gneisses as well as initial ⁸⁷Sr/⁸⁶Sr values of 0.7036–0.7037 for the gabbroic rocks and 0.7026–0.7027 for the ultramafic rocks suggest a mantle source for this rock association. The geochemical characteristics of the garnet–hornblende–plagioclase gneisses indicate that their precursors were derived by fractional crystallization from a basaltic parent magma, by the same process which produced the adjacent clinopyroxene norites and ultramafic cumulates as well. The combined U–Pb upper intercept ages of zircons from two gneiss samples yield an igneous crystallization age of 532±30 Ma, similar to previously dated (mostly calc-alkaline) orthogneisses in the same area. High-quality transparent zircons showed the least degree of discordance, but contain extremely low U and Pb levels. The rock suite, including this plagiogranite, was emplaced within oceanic crust which formed in the latest Precambrian–early Palaeozoic off the northern continental margin of Gondwana. Received: 26 April 1996 / Accepted: 2 August 1996     

Geochemische und 13C/12C-isotopenchemische Untersuchung zur Herkunft der Kohlensäure in mineralhaltigen Wässern Nordhessens (Deutschland)

Geochemical and ¹³C/¹²C-isotopical Investigation of Mineral Waters in Northern Hessia (Germany) and the Origin of their CO₂ Content The dissolved carbonate originates from three sources: 1. biogenetic soil-CO₂, 2. volcanic CO₂ related to the evaporites of the Zechstein formation, and 3. carbonate derived from the dissolution of limestones and dolomites. Miocenic basaltic melts penetrated the evaporites of the Zechstein, and the related CO₂ was trapped in the intra- and intergranulars of the salt minerals. Circulating meteoric waters dissolve the salt minerals releasing CO₂ gas. Thus, the occurrence of basalt is related to the CO₂ contents of the evaporites, and the dissolution of only small amounts of salts rich in CO₂ may result in a high concentration of carbonic acid. In waters rich in carbonate, where volcanic CO₂ dominates over the other two sources of carbon, a δ¹³C-value of “salt-CO₂” of about –1‰ (PDB) is obtained. Water with less dissolved carbonate species have smaller quantities of salt-CO₂ down to about 20%.     

THE CASE STUDY ON THE EFFECT OF CO_2 IN CAVE ATMOSPHERE ON STABILITY OF SPELEOTHEM SCENERY IN YAOLIN CAVE, ZHEJIANG PROVINCE, CHINA

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The CO2 Discharge in the Boundary Fault Areas of the Sichuan-Yunnan Block and Its Sources

A large number of CO2 springs outcrop along the boundary faults of the Sichuan-Yunnan block and in their neighboring areas.These springs are of a roughly similar distribution as the epicenters of strong earthquakes since 1900.This similarity indicates that the CO2 discharges could be directly related to the modern seismic activity in that area.The evidences of stable carbon and oxygen isotopes indicate that an overwhelming majority of the CO2 released from modern active faults is derived from the deep earth crust.There are 2 main mechanisms of CO2 discharge.Modern active faults are able both to produce directly a lot of CO2 due to thermodynamic metamorphism and to provide passages for the CO2 constituent coming from the lower crust or upper mantle.By continuously monitoring the dynamic changes of CO2 discharges,it would be possible to obtain the information of earthquake precursors that reflect the physical and chemical changes of the earthquake sources.     

从西藏扎仓茶卡Ⅱ湖提取Li_2CO_3的简化工艺

藏北高原恶劣的自然地理条件使扎仓茶卡珍贵的锂资源的开发极为困难,必须采用尽可能简化的提取工艺才能降低成本。本文提出一种经CaO、（NH_4）_2C_2O_4和Na_2CO_3三步沉淀得到粗Li_2CO_3的简化工艺,其产品纯度可达85.62％,总回收率约20％,卤旦回收率约为76％。     

大洋钻探与大洋地壳研究

近代地球科学有两大发展趋势：一是向地球深部延伸，目的于探查地球深部的物质组成与作用过程，其代表性学科即地球动力学；二是向全球性扩展，把区域性的地学问题同全球变化联系起来，研究大气圈，生物圈，水圈和冰冻圈的变化及其复杂的相互作用，代表性学科即广义的环境科学。由于海洋占地球表面的７１％以上，洋壳只有５～６ＫＭ，海底又有丰富的矿产资源，因此人类目前比以往任何时候都更加重视海洋科学的研究。多国合作、学科光     

大洋钻探与世界油气资源

全球地质学的进展，包括层序地层学以及沉积盆地数值模拟，极大地推动了油气勘探理论和实践，全球事件的研究揭示了世界油气资源的生成和分布的控制机理。     

Detection of Anthropogenic CO2 Emission Signatures with TanSat CO2 and with Copernicus Sentinel-5 Precursor (S5P) NO2 Measurements: First Results

China’s first carbon dioxide(CO₂) measurement satellite mission, TanSat, was launched in December 2016. This paper introduces the first attempt to detect anthropogenic CO₂ emission signatures using CO₂ observations from TanSat and NO₂ measurements from the TROPOspheric Monitoring Instrument(TROPOMI) onboard the Copernicus Sentinel-5 Precursor(S5P) satellite. We focus our analysis on two selected cases in Tangshan, China and Tokyo, Japan.We found that t...     

基于卫星遥感的南海海-气CO2通量研究

海洋是地表环境中最重要的碳库,准确估算CO2在海洋与大气之间的交换对于进一步阐明其变化过程机理具有重要意义。利用南海2011—2020年的海温、风速、海平面气压等多种遥感反演数据,基于海-气分压差算法,构建了海-气CO2通量遥感估算模型,并分析其时空变化特征。结果表明：（1） 遥感估算模型在整个南海海域具有较好的通用性,对比实测区域数据,估算结果的平均绝对误差和均方根误差分别为1.04和1.37 mmol/(m2·d);对于源汇区的识别准确率达到90.63%。（2） 南海总体表现为弱碳源,CO2通量的季节变化呈现出夏秋季高、冬春季低的特征,夏季和冬季分别为全年最高和最低。空间分布特征为南北部差异大。碳汇高值区始终位于北部,且冬季为强碳汇,而碳源高值区夏季出现在中南半岛东南部,秋季则转移到南海东北部。（3） 南海三种典型区（北部陆架陆坡、中部海盆、南部陆坡）的CO2通量随时间推移均呈现降低的趋势,且北部下降速度最快。2011—2020年,南海年均向大气净释放碳1.51×107 t,但其碳释放量呈降低趋势,降低速度为2.03×106 t/a,南海总体的“碳源”强度有所减弱。研究结果可为制定碳排放及碳交易政策提供科学参考。     

Numerical modelling of dyke interaction and its influence on oceanic crust formation

Dykes are an essential element in building oceanic crust, most prominent in sheeted dyke complexes in the upper crust. Since dykes alter the magnitude and orientation of the local stress field, they cannot be treated as passive infillings of extensional fractures.We use a quasi-static, iterative 2-D boundary element method allowing for a wholesale movement of fluid-filled fractures. Effects of stress and pressure gradients, buoyancy and enclosed fluid mass are considered. The implications of the dyke-induced stress field are analysed combining the simulation of fracture propagation with computation of dyke interaction. Dyke interaction occurs by the adaptation of ascending dykes to the stress field caused by previous fractures arrested in the crust and leads to focussing and crossing of dykes. Examples for applications are introduced, concerning e.g. the generation of a magma chamber and the formation of the sheeted dyke complex. Our main results are that the interaction between dykes can be considerable and that the most important controlling factor is stress. The interaction is small when the horizontal tensional stress is large compared to the pressure in the dyke head. Otherwise, dykes tend to attract each other and to form centres of high dyke density or sill layers.