江西九江红土生物标志化合物的分布特征及其古气候环境意义     

彭红霞  詹成  马瑞元  顾延生  胡圣虹 《地球学报》2019,40(3):447-455

为了探求江西九江红土地层中所记录的古气候环境信息,论文在对江西九江红土剖面的野外地貌、岩性和相关沉积环境调查分析基础上,利用气相色谱-质谱联用仪对正构烷烃、一元正脂肪酸等生物标志化合物进行了研究,着重分析了正构烷烃和一元正脂肪酸的来源及其碳数分布特征。结果显示:江西九江红土剖面上部均质红土中正构烷烃的CPI、∑C_(21)~–/∑C_(22)~+及一元正脂肪酸的CPI_L值均大于其下部的网纹红土,且波动较为明显,表明网纹红土的形成气候比其上的均质红土形成时期气候暖湿,反映了中更新世中期(600～300kaBP)的极端暖湿期;正构烷烃的∑C_(21)~–/∑C_(22)~+、(C_(15)+C_(17)+C_(19))/(C_(27)+C_(29)+C_(31))、(C_(16)+C_(17)+C_(18))/(C_(29)+C_(31)+C_(33))、C_(17)/C_(31)在剖面上表现出一致的旋回性变化,反应了江西九江中更新世以来气候的冷暖旋回变化。结果表明红土地层中的生物标志化合物具有很好的古气候环境意义。  相似文献   

遥感技术在广东省丰顺县地质灾害详细调查中的应用     

杨羿  刘瑞强  李海崇  李程 《地质灾害与环境保护》2019,30(1):83-90

广东省梅州市丰顺县地处粤东北部地质灾害高发区,是广东地质灾害重点防治区之一。地质灾害的频繁发生,严重影响国家发展和人民生命财产安全。本文以SOPT、ETM+影像和Google Earth Pro软件中的多时相高空间分辨率影像为主要数据,在丰顺县进行遥感地质灾害解译调查,建立了丰顺县地区滑坡、崩塌、不稳定斜坡等地质灾害的解译标志,共解译滑坡52处,不稳定斜坡33处,崩塌10处,地质环境点8处。通过三维多时相高分辨率影像,精细解译地质灾害,分析灾害形成诱因和发育地质环境条件。研究结果表明,遥感技术可以快速、高效地解译出丰顺县地质灾害的种类、规模以及分布特征,完成地质灾害详细调查的前期任务,为地面详细调查提供方向和路线。  相似文献   

西藏八宿吉利地区新发现寒武纪变质花岗岩锆石U-Pb年龄、地球化学特征及其地质意义   总被引：1，自引：1，他引：0       下载免费PDF全文

康朝龙  代克刚  李海波  梁成  陈晓深  扎西  王天泽  李静 《沉积与特提斯地质》2019,39(2):1-13

八宿吉利地区寒武纪变质花岗岩位于曲扎湖-提卡一带,主要由变质二长花岗岩和变质花岗闪长岩组成。这一新发现对于认识和恢复原特提斯构造历史演化具有重要意义。锆石CL图像显示变质花岗岩锆石为岩浆成因。锆石LA-ICP-MS测年得出片理化变质二长花岗岩年龄为503.7±4.7Ma、变质花岗闪长岩年龄为494.7±3.4Ma,表明该岩体形成时代属于寒武纪。通过岩石地球化学分析,变质二长花岗岩SiO2含量介于69.87%~79.89%之间;变质花岗闪长岩SiO2含量介于66.63%~70.15%之间。前者Al2O3含量变化于12.36%~14.82%,Na2O含量为2.54%~7.16%,K2O含量为0.15%~5.95%,K2O/Na2O=0.02~2.34;后者Al2O3含量变化于14.66%~15.41%,Na2O含量为3.60%~5.63%,K2O含量为0.77%~2.78%,K2O/Na2O=0.14~0.77,属于钙碱性-碱性过铝质花岗岩。在侵入岩构造环境Rb-(Y+Nb)判别图解、Rb-(Yb+Ta)判别图解中,样品均落入“火山弧花岗岩”区域中,表明其形成于大陆边缘火山弧环境。结合锆石测年结果及区域地质背景分析,认为吉利地区变质花岗岩形成于冈瓦纳大陆裂离卡穷微陆块阶段,同时表明原特提斯洋形成最早时限可追溯至寒武纪。  相似文献   

Ore Genesis and Tectonic Significance of the Xiaojiashan Tungsten Deposit,Eastern Tianshan,Xinjiang, China: Evidence from Geology,Fluid Inclusions,and Stable Isotope Geochemistry     

Yunfei Zhou  Jiuhua Xu  Lihua Shan  Xihui Cheng  Yueping Deng  Wenhuan Feng  Lingxiao Qiao 《Resource Geology》2019,69(1):43-64

The Xiaojiashan tungsten deposit is located about 200 km northwest of Hami City, the Eastern Tianshan orogenic belt, Xinjiang, northwestern China, and is a quartz vein‐type tungsten deposit. Combined fluid inclusion microthermometry, host rock geochemistry, and H–O isotopic compositions are used to constrain the ore genesis and tectonic setting of the Xiaojiashan tungsten deposit. The orebodies occur in granite intrusions adjacent to the metamorphic crystal tuff, which consists of the second lithological section of the first Sub‐Formation of the Dananhu Formation (D₂d ₁²). Biotite granite is the most widely distributed intrusive bodies in the Xiaojiashan tungsten deposit. Altered diorite and metamorphic crystal tuff are the main surrounding rocks. The granite belongs to peraluminous A‐type granite with high potassic calc‐alkaline series, and all rocks show light Rare Earth Element (REE)‐enriched patterns. The trace element characters suggest that crystallization differentiation might even occur in the diagenetic process. The granite belongs to postcollisional extension granite, and the rocks formed in an extensional tectonic environment, which might result from magma activity in such an extensional tectonic environment. Tungsten‐bearing quartz veins are divided into gray quartz vein and white quartz veins. Based on petrography observation, fluid inclusions in both kinds of vein quartz are mainly aqueous inclusions. Microthermometry shows that gray quartz veins have 143–354°C of T_h, and white quartz veins have 154–312°C of T_h. The laser‐Raman test shows that CO₂ is found in fluid inclusions of the tungsten‐bearing quartz veins. Quadrupole mass spectrometry reveals that fluid inclusions contain major vapor‐phase contents of CO₂, H₂O. Meanwhile, fluid inclusions contain major liquid‐phase contents of Cl^?, Na⁺. It can be speculated that the ore‐forming fluid of the Xiaojiashan tungsten deposit is characterized by an H₂O–CO₂, low salinity, and H₂O–CO₂–NaCl system. The range of hydrogen and oxygen isotope compositions indicated that the ore‐forming fluids of the tungsten deposit were mainly magmatic water. The ore‐forming age of the Xiaojiashan deposit should to be ~227 Ma. During the ore‐forming process, the magmatic water had separated from magmatic intrusions, and the ore‐bearing complex was taken to a portion where tungsten‐bearing ores could be mineralized. The magmatic fluid was mixed by meteoric water in the late stage.  相似文献   

In Situ U‐Th‐Pb Dating and Sr‐Nd Isotope Analysis of Bastnäsite by LA‐(MC)‐ICP‐MS     

Yue‐Heng Yang  Fu‐Yuan Wu  Qiu‐Li Li  Yamirka Rojas‐Agramonte  Jin‐Hui Yang  Yang Li  Qian Ma  Lie‐Wen Xie  Chao Huang  Hong‐Rui Fan  Zi‐Fu Zhao  Cheng Xu 《Geostandards and Geoanalytical Research》2019,43(4):543-565

Bastnäsite is the end member of a large group of carbonate–fluoride minerals with the common formula (REE) CO₃F·CaCO₃. This group is generally widespread and, despite never occurring in large quantities, represents the major economic light rare earth element (LREE) mineral in deposits related to carbonatite and alkaline intrusions. Since bastnäsite is easily altered and commonly contains inclusions of earlier‐crystallised minerals, in situ analysis is considered the most suitable method to measure its U‐Th‐Pb and Sr‐Nd isotopic compositions. Electron probe microanalysis and laser ablation (multi‐collector) inductively coupled plasma‐mass spectrometry of forty‐six bastnäsite samples from LREE deposits in China, Pakistan, Sweden, Mongolia, USA, Malawi and Madagascar indicate that this mineral typically has high Th and LREE and moderate U and Sr contents. Analysis of an in‐house bastnäsite reference material (K‐9) demonstrated that precise and accurate U‐Th‐Pb ages could be obtained after common Pb correction. Moreover, the Th‐Pb age with its high precision is preferable to the U‐Pb age because most bastnäsites have relatively high Th rather than U contents. These results will have significant implications for understanding the genesis of endogenous ore deposits and formation processes related to metallogenic geochronology research.  相似文献   

大兴安岭北段巴升河岩体锆石U-Pb年代学及其地质意义     

陈会军  崔天日  钱程  李林川  陈井胜  李伟  吴新伟  江斌  司秋亮  秦涛  唐振  张渝金  郭威 《地质与资源》2019,28(5):405-412

大兴安岭北段扎兰屯地区巴升河岩体由碱长花岗岩组成.采用LA-ICP-MS方法对碱长花岗岩开展锆石U-Pb测年,结果为297.8±3.6 Ma,岩体形成于早二叠世.该岩体4个样品的全岩地球化学等特征显示：巴升河岩体中碱长花岗岩具有富Si、高K、富碱的特征,属于弱过铝质钾玄岩系列,同时,样品∑REE偏高,Eu负异常明显,富集大离子亲石元素,具有A型花岗岩特征,综合前人研究成果及同位素年代学特征,认为兴安地块与松嫩地块拼合的时间早于298 Ma.  相似文献   

Simulation of long-term thermo-mechanical response of clay using an advanced constitutive model     

Zymnis  Despina M.  Whittle  Andrew J.  Cheng  Xiaohui 《Acta Geotechnica》2019,14(2):295-311

Acta Geotechnica - There is extensive data to show that heating and cooling produces irrecoverable deformations in clays under fully drained conditions. The effects are most pronounced for normally...  相似文献   

Fracture grouting and geonails for soft soil tunnelling     

Y. M. Cheng  S. K. Au  H. Wong 《Geomechanics and Geoengineering》2019,14(2):99-117

To stabilise the tunnel faces and slopes in soft clay for the Airport Link construction in Australia, fracture grouting and glass fibre-reinforced plastic (GFRP) soil nails are proposed for the soil improvement as well as ease of handling. The compensation caused by the fracture grouting and the gain in strength due to consolidation as well as the geonail have stabilised the soft clay during construction. Only a small amount of ground settlement during soft clay box-jacking operation is generated so that the railway traffic above the embankment can be maintained without interference. The design method of the fracture grouting ground improvement study for this difficult project is discussed in this paper. Extensive laboratory and field tests were employed to verify the design assumptions and to fine-tune the ground improvement studies. The success of this project in poor ground conditions results from combined efforts of extensive field tests, an improved ground improvement design method and a realistic numerical analysis to assess the unstable/highly stressed zones for the placement of soil reinforcement.  相似文献   

Microbially induced calcite precipitation along a circular flow channel under a constant flow condition     

Wu  Chuangzhou  Chu  Jian  Wu  Shifan  Cheng  Liang  van Paassen  Leon A. 《Acta Geotechnica》2019,14(3):673-683

Biogrouting is a new ground improvement method that has been studied in recent years. This method involves mainly the use of a microbially induced calcite precipitation process to bind soil particles to increase the strength or to fill in the pores of soil or joints of rock for seepage control. There are two major challenges in the use of biogrout for seepage control through rock joints. The first is how to inject the biogrout solutions, and the second is to understand the mechanisms for the formation of calcite under seepage flow. In this paper, a study on the injection of biogrout solution and the formation of precipitates along a circular 1D flow channel is presented. To minimize the influence of flow, a new one-phase injection method to inject bacterial solution and cementation agents simultaneously was adopted in this study. Factors affecting the formation and distribution of precipitates along the flow channel such as flow velocity, flow rate, and aperture of flow channel were investigated. The experimental results indicated that less calcite was precipitated at locations further away from the injection point due to depletion of the reactants’ concentrations along the flow path. Using the one-phase injection method, the bacterial activity had a major effect on the accumulation of the calcite on the inner surface of the flow channel. The total calcite precipitated on the surface of the flow channel increased slightly with increasing bacterial activity or flow rate. An equation to predict the distance travelled by the biosolution has been derived based on the testing results.

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史灌河流域水量平衡研究   总被引：3，自引：0，他引：3  

彭顺风  钱名开  徐时进  徐慧  程兴无 《气候与环境研究》2001,6(2):234-239

建立了一个水量平衡模型,并用1998、1999年淮河流域能量和水循环试验(HUBEX)期间获得的史灌河流域(HUBEX水文试验区)加密观测资料来率定模型中的参数.结论表明:(1)水量平衡的要素计算合理;(2)梅山、鲇鱼山、蒋集土壤含水量的平均值系列基本上反映了流域蓄水量的变化过程;(3)流域蓄水量的衰减系数、蒸发能力的折算系数比较稳定,不应通过调整这些系数来实现水量平衡.  相似文献