青海索拉沟银多金属矿床成矿特征及成因探讨

索拉沟地区位于青海省东昆仑东部与西秦岭造山带的接合部位,地质构造复杂,岩浆活动较强烈,成矿背景条件良好,是青海省贵金属、铜多金属重要的成矿带之一。根据矿床产出的地质构造环境、成矿特征、矿物组成、电子探针、流体包裹体温压测试及元素组合等特点分析,推测矿床的形成经历了热水沉积成矿和热液叠加改造成矿,索拉沟银多金属矿为热水沉积-热液叠加改造型。     

藏北祖尔肯乌拉山地区新生代高钾钙碱岩系火山岩同位素地球化学研究

通过对藏北祖尔肯乌拉山地区新生代高钾钙碱岩系火山岩Sr,Nd,Pb同位素成分的系统测试分析表明,火山岩具有相对高的^87Sr／^86Sr和低的^143Nd／^144Nd值及高的Pb同位素组成特点,且Sr,Nd,Pb同位素比值变化范围很窄,反映了其具有同源岩浆的特点,并且经历了类似的地球化学动力学过程。Sr,Nd,Pb同位素组成及相关图解判别表明,藏北祖尔肯乌拉山地区新生代高钾钙碱岩系火山岩来源于被大洋沉积物和地壳物质所混合的不均一富集地幔源区,显示源区具有壳幔混源性质,与EMⅡ型富集地幔源特征一致。     

Nature and Evolution of Pre-Neoproterozoic Continental Crust in South China: A Review and Tectonic Implications

South China as an amalgamation of the Yangtze and Cathaysia blocks is composed of Archean to Mesoproterozoic basement overlain by Neoproterozoic and younger cover. Both the constituent Yangtze and Cathaysia blocks contain well-preserved Neoproterozoic rocks that have been extensively studied in terms of the age and tectonic nature, but less is known about their earlier crustal history due to the incomplete rock record. Recent efforts in investigating the yet survived crustal nature based on isotopic and elemental signatures preserved in igneous and sedimentary rocks have steadily improved our knowledge about the pre-Neoproterozoic continental crustal evolution in South China. In this paper, we summarize the up-to-date pre-Neoproterozoic records, including petrological, geochronological, geochemical and geophysical data, across South China, and discuss its spatiotemporal patterns of the pre-Neoproterozoic crust and the relevant tectonic events. While the xenocrystic/inherited and detrital zircon records suggest widespread Archean (mainly ca. 2.5 Ga) crustal components within both the Yangtze and Cathaysia blocks, exposed Archean rocks are only limited to isolated crustal provinces in the Yangtze Block. These Archean rocks are dominated by TTGs (tonalite-trondhjemite-granodiorite) with varied ages (3.3–2.5 Ga) and zircon Hf isotopes, indicating a compositionally heterogeneous nature of the Archean Yangtze Block and, by inference, the development of multiple ancient terranes. The early Paleoproterozoic (2.4–2.2 Ga) tectonomagmatic events characterize the western Yangtze Block and are supportive of an east-west subdivision of the Yangtze basement, whereas the late Paleoproterozoic (2.1–1.7 Ga) orogeneses may have affected a larger area covering both the western and eastern parts of the Yangtze Block, and also the Cathaysia Block. The eastern Yangtze Block with generally northeastward-younging late Paleoproterozoic magmatism and metamorphism likely experienced a prolonged 2.05–1.75 Ga orogenic process welding the various Archean proto-continents, consistent with the documentation of a buried late Paleoproterozoic orogenic belt imaged by deep seismic profiling from its central part and of a slightly older ophiolitic mélange in the northern part. The Cathaysia Block was probably involved in a short-lived 1.9–1.8 Ga orogenic event. The two orogeneses overlapped in time and may have contributed to the cratonization of a possible unified South China, and are referred to be linked with the assembly of the Nuna Supercontinent. The subsequent late Paleoproterozoic to early Mesoproterozoic rift successions and intrusions (1.7–1.5 Ga) in the southwestern Yangtze Block, and the ca. 1.43 Ga rifting in Hainan Island of the Cathaysia Block could be responses to the Nuna break-up. Late Mesoproterozoic (1.2–1.0 Ga) magmatism of varied age and nature in different localities of the Yangtze Block is reflective of a complex tectonic process in the context of the assembly of the Rodinia Supercontinent. Similar-aged metamorphism (1.3–1.0 Ga) is recorded in Hainan Island, reflecting the Grenvillian continental collision during the Rodinia assembly, but further studies are necessary to better constrain the late Mesoproterozoic tectonic framework of South China.     

大连“11．28”翻船事故风浪分析

利用自动气象站资料、常规气象观测资料、NCEP全球再分析资料及WAVEWATCH III模式预报资等料对2012年11月28日大连翻船事故的大风大浪实况、事故成因及演变情况进行分析。结果表明：大连此次翻船事故高空的强冷空气促使冷涡加强,西部大陆高压和蒙古气旋不断加强东移,东南部海上高压稳定少动,蒙古气旋底前部与海上高压顶后部梯度加大,梯度密集区正好位于渤海海峡,造成黄海和渤海偏西大风;低层辐散和中层辐合的垂直结构加强了低层以下的上下扰动,构成南北垂直环流,中层以下动力强迫下沉气流将北侧中层的动量下传至辽东半岛南部地面及黄海、渤海海面,使其不断获得动能,有利于偏西大风的加强;西南向岸大风有利于浪高增长,偏西大风及与其同时增长的大浪是大连地区此次翻船事故的主要原因。     

"2005-05-31"暴雨天气过程多普勒雷达回波分析

通过对2005年5月31日贵州省一次强降水的雷达回波强度、速度的分析,发现此次暴雨过程具有较为典型的冷锋过境的雷达回波特征,暴雨落区与雷达回波强度、移速有关,暴雨出现在逆风区附近.     

四川九寨沟诺日朗瀑布钙华大坝放射性及沉积环境意义

以九寨沟诺日朗瀑布钙华大坝为研究对象,采用便携式手持伽马仪对大坝坝体进行放射性强度测量,同时对钙华大坝取样,进行主量、微量元素分析,以研究大坝形成的沉积环境.结果表明:大坝表层伽马辐射量平均值为27.57 Ur(当量铀),变异系数为18.73％;钙华主微量元素分析显示钙华颜色与本身所含的色素元素和矿物有关;大坝钙华(L...     

Titanium Isotope Analysis of Igneous Reference Materials using a Double-spike MC-ICP-MS Method

Ti separation was achieved by ion-exchange chromatography using Bio-Rad AG 1-X8 anion-exchange and DGA resins. For high-Fe/Ti and high-Mg/Ti igneous samples, a three-column procedure was required, whereas a two-column procedure was used for low-Fe/Ti and low-Mg/Ti igneous samples. The Ti isotopes were analysed by MC-ICP-MS, and instrumental mass bias was corrected using a 47Ti-49Ti double-spike technique. The 47Ti-49Ti double-spike and SRM 3162a were calibrated using SRM 979-Cr, certificated value 53Cr/52Crtrue = 0.11339. Isobaric interference was evaluated by analysing Alfa-Ti doped with Na, Mg, Ca, and Mo, and results indicate that high concentrations of Na and Mg have no significant effect on Ti isotope analyses; however, Ca and Mo interferences lead to erroneous δ49/47Ti values when Ca/Ti and Mo/Ti ratios exceed 0.01 and 0.1, respectively. Titanium isotopic compositions were determined for 12 igneous reference materials, BCR-2, BHVO-2, GBW07105, AGV-1, AGV-2, W-2, GBW07123, GBW07126, GBW07127, GBW07101, JP-1, and DTS-2b. Samples yield δ49/47Ti (‰) of ?0.035 ± 0.022, ?0.038 ± 0.031, 0.031 ± 0.022, 0.059 ± 0.038, 0.044 ± 0.037, 0.000 ± 0.015, 0.154 ± 0.044, ?0.044 ± 0.018, 0.010 ± 0.022, 0.064 ± 0.043, 0.169 ± 0.034, and ?0.047 ± 0.025 (relative to OL-Ti, ±2SD), respectively; of which isotopic compositions of DTS-2b, JP-1, GBW07101, GBW07105, GBW07123, GBW07126, and GBW07127 are reported for the first time. Standard Alfa-Ti was analysed repeatedly over a ten-month period, indicating a reproducibility of ±0.047 (2SD) for δ49/47Ti, similar to the precisions obtained for geochemical reference materials.     

极端干旱沙漠中无沙埋干扰时几种固沙植物栽植试验研究

沙埋干扰是沙漠地区乡土植物生存繁殖的必要条件。在塔克拉玛干沙漠腹地,无沙埋干扰地段大多是高矿化度地下水埋深较浅的地段,这些地段盐渍化较重。7a定点观测和试验表明,塔里木沙漠公路沿线丘间地栽植固沙植物逐渐死亡的主要因素不是沙层水分和沙层盐分,而是高矿化度地下水埋深太浅(0.8~1.0 m),即这类地段植物死亡的原因主要是由于植物长期吸收高矿化度地下水使得体内盐分积聚过多无法调节而造成的。因此,在干旱区高矿化度地下水埋深太浅的地段,无沙埋干扰时建立固沙植被应谨慎。     

青藏高原东北缘特提斯构造域界线的探讨

东特提斯构造域北界的确定不仅可以约束构造域的范围及演化,而且对于约束中国各陆块的原始构造归属也有着非常重要的意义.本文将从地球化学角度对这一科学问题进行探讨.祁连造山带早古生代蛇绿岩单元内枕状玄武岩的元素、Sr-Nd-Pb同位素组成系统研究表明：其地幔源区的Nd和Pb同位素组成均表现出印度洋MORB型同位素组成特征;枕状玄武岩（△^207Pb/^204Pb）t变化范围为9.1～24.3（平均值为14.7）,（△^208/^204Pb）t变化范围为9.1～101.1（平均值55.3）;与古特提斯和新特提斯蛇绿岩具有一致的同位素组成.因此,祁连造山带古洋幔应属于原特提斯构造域.纵观中国境内的特提斯构造域蛇绿岩的分布特征可知：该构造域表现出自北而南变年轻的时空演化规律,从而说明中央造山带的动力学过程也应纳入冈瓦纳大陆裂解和亚洲增生的总动力学系统之中.     

珠江口盆地珠三坳陷文昌组有机质碳同位素异常成因

部分中国近海湖盆和大西洋裂谷盆地发现了腐泥型有机质碳同位素偏重的现象,并伴随异常高总有机碳含量和生烃潜力。本文依据泥岩有机碳测试、孢粉分析、主微量元素、泥岩和原油碳同位素及饱和烃色质色谱资料,并结合现代湖泊盘星藻发育特征,从有机质来源、古环境条件和有机质保存改造三个方面探讨了珠江口盆地珠三坳陷古近系文昌组碳同位素正偏移的成因机制。珠三坳陷文昌组碳同位素异常与气候、古生产力、古水深和藻类勃发等古环境因素有关。然而,从三级层序尺度看,古水深可能是一个不可忽视的重要因素：指示水深的Rb/K比值随深度加深而增加,与碳同位素和TOC含量变化趋势一致。同时现代湖泊研究也证实了盘星藻分布于不同水深范围,因此“深水型盘星藻”的繁盛很可能是珠三坳陷文昌组二段烃源岩碳同位素偏重的根本原因。