中国夏季降水对南印度洋偶极子的响应研究

分析了春季印度洋海表温度（SST）与中国160个站夏季降水的关系,得到:印度洋全海盆的增温趋势与我国夏季降水的气候线性变化趋势是十分一致的。另外,热带外南印度洋出现西南印度洋为正（负）、其东北部出现（负）正海温异常的分布模态时,定义为正（负）南印度洋偶极子PSIOD（NSIOD）事件。SIOD事件对中国夏季降水具有重要影响,PSIOD年,5月份中国江南和西南以及长江中下游的降水偏多;6～8月份华北、东北区域、长江中游以及华南地区降水增多,华南与华北之间的区域降水偏少,即主要为两条雨带的分布。NSIOD年,5月份中国大部降水偏少; 6～8月中国西南、江南地区以及黄淮地区降水偏多。不同时段SIOD所起的作用是不同的,5月,SIOD主要通过改变马斯克林局地环流的变化,影响印度洋低层越赤道的水汽通量输送;6～8月,通过改变海洋大陆下垫面SST热状态,改变其上空对流强度以及水汽输送方向,并间接影响西北太平洋副热带高压的强度和南北位置,进而对中国雨带的分布产生影响。     

Early J2 basalts in SE China: Incipience of large-scale late Mesozoic magmatism

Magmatism in SE China was dormant during 204–180 Ma, but was reactivated in 180–170 Ma (early J₂), and then became more and more intensive towards the end of early Cretaceous. The small-scale early J₂ magmatism is the incipience to long-term and large-scale magmatism in this region. A near east-west (EW) trend volcanic belt was distributed across south Hunan, south Jiangxi and southwest Fujian was formed during early J₂ time. Along this belt from the inland toward the coast, the lithology of basalts changes from alkali into tholeiite, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. On the basis of geochemical characteristics of these basalts, we infer that the melting degree of source rocks and the extent of fractional crystallization and crustal contamination all increased whereas the depth of mantle source decreased from the inland to the coast, which led to the variations of geological characteristics of the volcanic belt. In early J₂, the western spreading Pacific plate began to subduct underneath SE China continental block, reactivating near EW trend deep fault that was originally formed during the Indosinian event. The stress of the western spreading Pacific plate and the extent of asthenosphere upwelling increased from the inland to the coast, which is consistent with the generation and evolution of early J₂ basalts.     

2014年2月12日于田7.3级大震对青藏东北缘地震活动的影响分析

First of all,using the GPS velocity field from campaign GPS measurements implemented by CMONC( C hina Crustal Movement Observation) a nd TEONC( C hina Tectonic Environment Observation Networks) u p to 2013, w e analyzed the background of regional crustal horizontal movement and deformation before the M S7. 3 Yutian,Xinjiang earthquake on February 12,2014. Then,by comparing this to the vertical movement from leveling measurements,we studied the crustal movement deformation and the state of strain accumulation on the northeastern edge of Qinghai-Tibetan block.Finally,we investigated the possible effects on the earthquake activity of the northeastern edge of Tibet from the M S7. 3 Yutian earthquake. The result indicates that,the M S7. 3Yutian earthquake occurred against the background of strong tectonic movement and intensive intracontinental crustal differential movement on the edges of tectonic blocks in western China,and also that it happened in the period of the strong tectonic stress field in Qinghai-Tibetan block and its edges. The sinistral strike-slip and stress transfer of the Yutian M S7. 3 earthquake may accelerate the rupture of fault segments with high strain accumulation at the northeastern edge of Qinghai-Tibetan block( especially in Qilian Mountain fault zone,and border area of Gansu,Qinghai and Sichuan provinces on the south of western Qinling).     

Three-dimensional modeling of bank erosion and morphological changes in the Shishou bend of the middle Yangtze River

This paper presents a three-dimensional (3-D) numerical model to simulate morphological changes in alluvial channels due to bank erosion. A method for the simulation of bank erosion is established. This is incorporated into a 3-D mathematical model for turbulent flow and non-uniform, non-equilibrium sediment transport. This model is applied to simulate morphological changes in the Shishou bend of the middle Yangtze River in China, where serious bank erosions occurred during the last two decades. The double-layer sediment structure of the riverbank on the middle Yangtze River is taken into account in the bank erosion module. Both cohesive and non-cohesive bank material in the different layers are considered. The bank erosion module also includes other factors affecting the rate of bank erosion, such as the longitudinal length of failed bank, the thickness of each layer in the double-layer structure, and the erosion-resisting effect of cohesive material from the top layer of failed bank. A locally-adaptive grid system is proposed to efficiently simulate the lateral migration of alluvial channel due to bank erosion. The predictive capability of the 3-D model is examined by laboratory data. Simulated processes of bank erosion agree with field observations in the Shishou bend during the period of October 1996–October 1998, and the bank erosion module plays a significant role in simulating morphological changes of the study reach. In addition, the equivalent channel-forming discharge, which is defined as a constant discharge that can create the same amount of bank erosion in an alluvial channel as that created by natural runoff processes during the same period of time, is proposed to improve calculation efficiency for feasibility studies.     

金沙江上游特米古滑坡堰塞湖成因与演化

金沙江上游巴塘—中咱河段位于青藏高原东南缘,该河段两岸岸坡发育众多的大型古滑坡,且部分古滑坡曾堵塞金沙江形成了堰塞湖,特米大型古滑坡堰塞湖是其中之一。关于特米古滑坡堰塞湖的形成与演化过程目前尚未见有过详细的报道。本文在野外调查的基础上,结合遥感影像解译和年代学测试,对特米古滑坡堰塞湖的地貌和沉积特征进行了详细研究,并对其形成与演化过程进行了分析。研究结果表明,特米古滑坡堰塞湖很可能是由该地区的古地震活动触发大型滑坡并堵塞金沙江形成的,最大湖面面积约为1.42×10⁷ m²,库容蓄水量约为1.46×10⁹ m³。该古堰塞湖的形成时间约为1.8 ka BP,其溃决消亡的时间约为1.4 ka BP,溃决洪峰流量约为55 858 m³/s,该滑坡堰塞湖持续稳定了约400年的时间。     

北羌塘盆地那底岗日剖面中上侏罗统碳酸盐岩稀土元素地球化学特征与沉积环境分析

北羌塘盆地那底岗日剖面中上侏罗统碳酸盐岩发育,其中以布曲组和索瓦组最为发育,对研究该区中上侏罗统沉积环境具重要意义。通过对稀土元素分布规律、分布特征及地球化学特征值分析,表明该套碳酸盐岩中稀土元素平均总含量(ΣREE)较低,为35.305μg/g;ΣLREE/ΣHREE比值为7.769～9.046,轻重稀土分馏明显,且稀土总含量(ΣREE)与SiO2和Al2O3含量呈正相关,与CaO含量呈负相关,说明沉积期有大量陆源碎屑注入。δCe平均值为0.966,基本无异常,但不同地层中有一定变化,布曲组到索瓦组一段、二段沉积水体氧化性显示为强-弱-强演化过程。LaN/YbN比值为1.124～1.493,其中索瓦组二段数值最小,沉积时期水体酸性最弱。表明研究区沉积水体具弱还原性,沉积时期有大量陆源碎屑注入,为近岸碳酸盐岩沉积。     

414矿床和栗木矿田的对比特征研究

通过414矿和栗木矿的含矿岩体及矿床特征的对比性研究表明;含矿花岗岩浆演化的相似性导致矿床特征的相似性;岩浆成分的差异与所处的地质、构造环境的不同是产生矿床之间差异的主要因素.     

西天山特克斯达坂晚古生代若干不整合的厘定及地质意义

地层不整合接触是研究地质发展历史及鉴定地壳运动特征和运动时期的重要依据。通过1：5万区域地质调查,在西天山特克斯达坂一带晚古生代地层中厘定出6个不整合面,证实区内乃至天山地区曾有过至少6幕褶皱运动,丰富了研究区的幕式褶皱内容。新确立了特克斯运动（东图津河组与科古琴山组之间的角度不整合）,证实了天山主褶皱幕是鄯善运动,是记录塔里木板块与准噶尔板块碰撞缝合的重要构造运动。特克斯运动等6幕褶皱运动为天山地区构造演化研究提供了更为详尽的幕式演化信息。     

砂岩中的凝灰质填隙物分异特征及其对油气储集空间影响--以鄂尔多斯盆地西北部二叠系为例

运用铸体薄片、扫描电镜、能谱分析及溶蚀实验等多种测试手段对鄂尔多斯盆地西北部二叠系砂岩填隙物进行了成份和成岩演化分析,认为砂岩中的填隙物主要为凝灰质填隙物,而不是普通意义上的粘土矿物。在有残余粒间孔隙或裂缝沟通的较开放性水环境里,凝灰质填隙物蚀变程度强,Si、Al、K、Na及Ca等离子因活性不同而发生分异,蚀变为“脏”高岭石及硅质团块等产物;封闭环境下,凝灰质填隙物保存完好,偏光显微镜下显示出似非晶态波状消光,活性强的K、Na元素含量仍然很高。凝灰质填隙物分异过程中,可以产生一定数量的溶蚀孔隙及晶间孔隙,砂岩储集性能得到了明显改善。对声波时差异常带砂岩进行大量的铸体薄片观察,证实了本区砂岩粒间溶蚀孔隙发育,凝灰质填隙物发生了强烈溶蚀。综合分析26口井的资料,发现垂向上凝灰质填隙物溶蚀强度呈箱型展布,箱内“脏”高岭石及溶蚀孔隙发育,箱顶部凝灰质填隙物含量高,保存好,并缺少“脏”高岭石团块出现。     

西准噶尔包古图地区地层火山岩锆石LA-ICP-MS U-Pb年代学研究

包古图地区位于西准噶尔东南部,区内出露地层主要为石炭系太勒古拉组、包古图组和希贝库拉斯组,为一套巨厚的半深海相-大陆坡相火山-火山碎屑沉积建造。这套地层的时代归属和地层层序长期以来一直存在争议。本文报导了包古图地区实测地层剖面,并从太勒古拉组玄武岩和包古图组及希贝库拉斯组凝灰岩中分别选出锆石,进行了LA-ICP-MS U-Pb年代学研究,获得²⁰⁶Pb/²³⁸U加权平均年龄分别为357.5±5.4Ma、332.1±3.0Ma和336.3±2.5Ma。由此确定这套地层属于早石炭世的杜内阶到维宪阶,由下到上依次为太勒古拉组、包古图组和希贝库拉斯组。