K–Ar illite dating to constrain multiple events in shallow crustal rocks: Implications for the Late Phanerozoic evolution of NE Asia     

《Journal of Asian Earth Sciences》2014

A recently developed illite-age-analysis (IAA) approach was applied to determine the multiple events for the Chugaryeong fault belt, Korea. Each event was determined by a combined approach of the optimized illite-polytype quantification and the K–Ar age-dating of clay fractions separated from the fault clays. The Late Cretaceous to Paleogene events (76.5 ± 0.8, 69.1 ± 0.6, 59.3 ± 0.7, and 48.2 ± 0.7 Ma) were recognized by calculating the authigenic 1M/1M_d illite ages on the IAA plots of the fault clays. The Early Cretaceous ages (121.7–124.7 and 112.4 ± 1.5 Ma) were also obtained from the convergent intercepts of 100% 2M₁ illite on the IAA plots. The absence of the 2M₁ illites in the host-rock indicates that the Early Cretaceous ages represent the timings of high-T hydrothermal events of >280 °C. The 2M₁ illites in the fault clays should be pre-formed by a fluid-rock interaction under a relatively high-T subsurface condition, and be mechanically reworked into the near surface along the fault by post-tectonic events. This is the first report determining the absolute age constraints of multi-activated tectonic events from a fault. These geochronological determinations of the multiple events recorded in the Chugaryeong fault belt are crucial to establish the tectonic evolution of the Korean Peninsula since the Late Cretaceous.  相似文献   

Use of shredded tyre waste in improving the geotechnical properties of expansive black cotton soil     

Amit Srivastava  Shikha Pandey  Jeeshant Rana 《Geomechanics and Geoengineering》2014,9(4):303-311

In recent years, geotechnical engineers are using tyre waste to alter the properties of soil for providing sustainable solutions to complex engineering problems. It is noted that black cotton soil, which is expansive in nature, covers a major portion of the Indian sub-continent, such as the Deccan plateau, Malwa plateau and a portion of Gujarat and poses challenging problems to infrastructural development in the region. In the present study, authors have characterised the geotechnical properties of black cotton soil, which is partially replaced with 4.75 mm passing – 2 mm retained (coarse fraction) and 2.0 mm passing - 75 micron retained (fine fraction) shredded tyre waste. The results of the experimental studies clearly show that partial replacement of black cotton soil with shredded tyre waste alters the geotechnical properties favourable to engineering applications and greatly reduces the swelling potential of the black cotton soil. It is noted that instead of fine fraction (2.0–0.075 mm), replacement with coarse fraction (4.75–2.00 mm) of shredded tyre waste can better be used for light weight fill behind the retaining walls as well as for embankment construction as it helps in reducing swelling pressure as well as improving the strength properties.  相似文献   

循化盆地晚渐新世-早中新世沉积物中黏土矿物特征及其古气候指示意义   总被引：1，自引：0，他引：1  

殷科  洪汉烈  李荣彪  徐耀明  杜鹃  季军良  张克信 《地质科技情报》2010,29(3)

采用X射线衍射、扫描电子显微镜分析方法,对青海循化盆地晚渐新世-早中新世沉积物中黏土矿物的微观形貌、体积分数、结晶度及其古气候指示作用进行了深入的研究。分析结果表明,晚渐新世盆地沉积物中的黏土矿物主要为蒙脱石、伊利石、坡缕石和绿泥石,以蒙脱石为主,指示循化地区总体为相对温暖潮湿的气候条件,蒙脱石、伊利石和绿泥石相对体积分数及伊利石、蒙脱石结晶度值均出现明显的周期性波动,表明循化地区气候经历了干旱-温暖潮湿交替的变化;早中新世盆地沉积物中的黏土矿物主要为伊利石、蒙脱石和绿泥石,以伊利石为主,各黏土矿物体积分数及伊利石、蒙脱石结晶度值的变化范围不大,表明循化地区气候以相对持续冷干为特征。从晚渐新世到早中新世,气候条件由相对温暖潮湿到相对冷干的转变,揭示其间(约21.3Ma)出现了一次极端的降温事件,可能与青藏高原隆升及亚洲沙漠化密切相关。  相似文献   

Red Clay Type Gold Deposits in China     

SUN Xiang  DENG Jun  WANG Qingfei  GONG Qingjie  YANG Liqiang  WANG Changming 《《地质学报》英文版》2010,84(6):1415-1427

<正>Red clay type gold deposits,located in the south of China,are situated not only in orogenic belts,but also in inner cratons,where climate is tropical-subtropical with clear arid and humid.The lateritic weathering crust often can be divided into five zones,including topsoil,siliceous duricrust zone,multi-color zone(or red clay zone in some deposits),pallid zone and saprolite zone from surface to the base rock,several of which are absent in some deposits.The base rocks are composed mainly of carbonate rocks with minor clastic rocks,intermediate-basic volcanic rocks and intermediate-acid and alkalic intrusions.The orebodies are mainly located in the multi-color zone with part of them in the pallid and saprolite zones.The ore sources include orebodies of Carlin-type gold deposits and porphyry gold deposits,as well as gold-rich base rocks.The red clay type gold deposits experienced early-stage endogenic gold mineralization and laterization during the Tertiary and Quaternary.The areas with endogenic gold deposits,especially Carlin-type gold deposits and porphyry gold deposits in karst depressions on the plateau,structual erosional platforms in the middle-lower mountains,and intermountain basins in southern China are well worth studying to trace red clay type gold deposits.  相似文献   

华南沿海第四纪类网纹红土的赋存层位及其年代问题   总被引：1，自引：0，他引：1  

朱照宇  吴翼  邱世藩  杨超  黄宁生  杨恬  曾敬  张金兰 《地球科学进展》2010,25(4):391-399

根据地质学、地貌学、沉积学、地球化学和年代学的研究,将华南沿海(南岭以南)不同时代的杂色粘土(暂称"类网纹红土")划分为基岩风化壳型和松散沉积风化壳型两种类型;将第四纪松散沉积系列中的杂色粘土划分为第四纪早期(年代为1.8～1.6 Ma BP)、中期(年代为1.0～0.8Ma BP)和晚期(年代为0.07～0.01 Ma BP)3个发育期;主要讨论了发育好、厚度大、分布广的第四纪中期杂色粘土与长江流域和西南丘陵区典型网纹红土之间在赋存层位、剖面结构和发育年代等方面的差别和存在问题,提出了需进一步研究杂色粘土-网纹红土的年代和发育规律及其反映的中国南方地质-气候环境演化规律等重要科学问题.  相似文献   

第四纪作为地质年代和地层单位的国际争议与最终确立     

姚玉鹏  刘羽 《地球科学进展》2010,25(7):775-781

第四纪(Quaternary)是地球科学中广泛使用的术语,代表地质年代中最晚的时段.在探讨全球环境变化趋势时,第四纪研究具有重要地位.但第四纪作为地质年代和地层单位的地位和底界问题,自18世纪提出以来,在国际学术界中就一直存在不同的观点;尤其是2004年部分权威学者和国际组织提出取消第四纪的方案,引发了激烈的国际大辩论.直到2009年,第四纪在地质年代中的正式地位及其底界划分方案,才最终获得了国际地科联的官方批准.回顾第四纪最初命名到正式地位确定的过程,特别强调了中国科学家立足于黄土等地质记录的研究工作,积极地参加了这场讨论,对于第四纪在地质学中的地位确立做出了重要贡献.  相似文献   

冻融作用对饱和粉质黏土抗剪性能的影响   总被引：4，自引：0，他引：4  

于琳琳  徐学燕  邱明国  闫自利  李鹏飞 《岩土力学》2010,31(8):2448-2452

为研究季节冻土地区冻融作用对道路边坡土体抗剪性能的影响规律,在不同冻结和融化温度、不同冻融循环次数、开放和封闭体系条件下对冻融饱和原状粉黏土试样进行了不固结、不排水剪切试验。试验结果表明:饱和原状粉质黏土冻融后,黏聚力降低,内摩擦角增大,冻结温度越低,冻融作用对黏聚力和内摩擦角的影响越小,随着冻融循环次数的增加,5～7次冻结循环后二者的变化逐渐趋于稳定。水分补给会强化冻融作用对试验土抗剪性能的影响;融化温度对试验土的抗剪性能影响很小。  相似文献   

成都粘土基坑支护技术应用研究     

付光强  吕建祥  杨俊 《四川地质学报》2010,30(2):225-228

成都粘土地层是目前基坑支护设计与施工中比较难以采用单独支护方式处理的一种地层。经对成都粘土地层不同深度的基坑进行总结和试验,通过比较提出对成都粘土地层支护的一些建议,可作为以后成都粘土地层支护的参考。  相似文献   

Properties and organic activation of ocean clay in the East Pacific     

Peiping Zhang    Xiaoguo Chi  Chunyan Tian  Baojun Wang  Huahua Lü  Xuefa Shi . College of Material Science  Engineering  Jilin University  Changchun  Jilin  China . College of Earth Sciences  Jilin University  Changchun  Jilin  China .Pivot Laboratory of National Ocean Department on Ocean Sediment  Environment Geology  the First Institute of National Ocean Research  Qingdao  Shandong  China 《东北亚地学研究》2006,9(1):19-29

In order to make use of ocean clay reasonably and excavate its potential applications the properties of ocean clay in Chinese investigating area of the East Pacific have been tested with the chemical analysis, XRFS, ICP/MAS, granulometry and SSA, etc. The results show that the clay sediments of this area are rich in clay minerals, fine granularity, bigger SSA, bigger water absorbability and lower ion changing ability etc. To improve the adaptability of ocean clay and macromolecule materials, using the dry milling method with silane, aluminate, stearic acid coupling agents etc the properties of ocean clay are improved. The effect has been evaluated by testing the water absorbing of the modified ocean clay and their dispersing in paraffin liquid. The result is that KH550 is better than any other active reagents, and the best activation technics is that 1.5 % （volume） of KH550 quantity, 20min of milling time. The DTA, XRD, SEM and IR analyses and SSA testing show that the organic activation can not change the mineral structure but can densify the structure of clay, and activation mechanism is chemical covered mainly and chemical combined secondly.  相似文献   

Red Clay Sediment in the Central Chinese Loess Plateau and Its Implication for the Uplift of the Tibetan Plateau     

Yougui Song  Jijun Li  Xiaomin Fang  Fei Xia  Hongmei Dong 《山地科学学报》2005,2(2):137-145

Introduction A set of reddish clay-silt-sized sediments named red clay underlying the Quaternary loess-paleosol sequence widely distribute in the Chinese Loess Plateau. The thickness of the red clay sediments ranges from decades of meters to over 100 m (Evan et al.1991,Mo and Derbyshire 1991, SUN et al. 1997&1998, DING et al. 1999, GUO et al. 2001, QIANG et al. 2001). Previous studies show that not only loess-paleosol (e.g.LIU et al.1985,AN et al.1990,DING et al.1992),but also red …  相似文献