川西高原甘孜黄土地层学   总被引：20，自引：2，他引：20  

蒋复初  吴锡浩  肖华国  赵志中  田国强  刘科 《地球学报》1997,18(4):413-420

本文初步研究了甘孜黄土地层，实测了甘孜县城西南郊新市区和满地两剖面，它们分别厚２３．７ｍ和２６．０ｍ。根据岩性、磁性地层特征、磁化率、ＣａＣＯ３质量分数测定和热释光测年结果，甘孜黄土可划分为冰后期Ｓ０复合古土壤，末次冰期Ｌ１复合黄土和末次间冰期Ｓ１复合古土壤等３个地层单位。布莱克反向极性亚时记录于底部Ｓ１ＬＬ１黄土中。甘孜黄土沉积始于晚更新世早期，大约为１２０ｋａＢＰ。甘孜黄土的磁化率变化反映了最近１２０ｋａ来的高原季风演化和气候环境变迁，６个磁化率高值段指示了６个夏季风环流增强的时段，６个磁化率低值段则  相似文献   

山西大同煤田晚石炭世晚期和早二叠世早期植物群   总被引：3，自引：2，他引：3  

陈芬  王京东 《现代地质》1997,11(2):131-136,T002

对山西大同煤田晚石炭世晚期和早二叠世早期植物化石进行了研究，共鉴定植物化石２１属４８种，划分２个植物组合，讨论了植物群的特征和时代；此外，还论证了本区晚石炭世晚期和早二叠世早期植物群指示的古气候条件  相似文献   

辽宁西部上侏罗统义县组研究新认识   总被引：37，自引：4，他引：37  

任东  郭子光 《地质论评》1997,43(5):449-459,T001

根据丰富的，最新的野外地质资料，对辽宁西部锦州和义县地区晚侏罗世义县组的岩石地层划分和对比中的重要问题进行了补充和修正。以《国际地层指南》的多重地层划分观点为基础，建立了一套完整的义县组岩石岩层单位。根据最新的原始鸟类以及昆虫，鱼，爬行类等生物化石研究结果，认为义县组的形成时期限于晚侏罗世晚期。  相似文献   

Late Paleozoic radiolarians from the Bentong-Raub suture zone, Peninsular Malaysia   总被引：3，自引：0，他引：3  

Frances C. P.  Spiller 《Island Arc》1996,5(2):91-103

Abstract Radiolarians extracted from marine siliceous sediments from the Bentong-Raub suture zone, Peninsular Malaysia have indicated a range of ages for olistostromal blocks of bedded chert, siliceous argillite and tuffaceous argillite, and chert clasts and lenses within the mélange from the suture zone. Late Devonian (Faniennian), Early Carboniferous (Tournaisian and Viséan) and Early Permian (Wolfcampian and Leonardian) ages are represented by seven radiolarian zones from ten localities along the suture zone. In stratigraphic order these include Holoeciscus 2–3 Assemblage Zones, Albaillella paradoxa Zone, Albaillella dejendrei Zone, Albaillella cartalla Zone, Pseudoalbaillella lomentaria Zone, Albaillella sinuata Zone and Pseudoalbaillella longtanensis Zone. Fifteen genera are represented by 35 species. The range of ages from Late Devonian to Early Permian suggests that an ocean existed between the Sibumasu and East Malaya terranes from at least Late Devonian to late Early Permian time and that closure of the ocean between the two terranes could not have occurred until after late Early Permian time. The range of ages and rock types from different depositional environments, indicate that the Bentong-Raub suture zone includes a disrupted accretionary complex.  相似文献   

大别造山带东部燕山晚期区域变质－岩浆活动与区域构造抬升的同位素地质年代学证据   总被引：14，自引：0，他引：14  

简平  马昌前  杨坤光 《地球科学》1996,(5)

应用Ｒｂ－Ｓｒ同位素地质年代学方法，系统地研究了大别山东部两类不同构造环境（同构造花岗岩和非构造花岗岩）成因的花岗岩及大别杂岩混合二长片麻岩的冷却就位和构造－变质时代．结合区域上大别杂岩和花岗岩已有的同位素地质年代学成果分析，结果表明：（１）大别山东部燕山晚期区域变质－混合岩化－岩浆活动是同一构造－热事件的产物；（２）大别杂岩与中生代花岗岩具有相似的热历史，中下地壳大别杂岩的出露是燕山晚期区域构造抬升的结果  相似文献   

四川晚二叠世煤中硫与成煤环境的关系   总被引：2，自引：0，他引：2  

唐跃刚  姚光华 《沉积学报》1996,14(4):161-167

本文从沉积学、成煤环境、地球化学等方面研究了煤中硫的分布规律，并详细阐明了煤中硫与成煤环境的关系。研究表明:煤中硫的赋存状况，不仅受成煤环境的影响，而且受其顶板沉积环境的影响。成煤环境奠定了煤中硫的分布基础，而顶板环境则是促使煤富硫、高硫的重要因素。微咸水浑水潮坪的顶板沉积环境，导致了下伏煤高黄铁矿硫，而咸水的清水潮坪顶板环境则导致下伏煤高有机硫。  相似文献   

赣东北蛇绿混杂岩带中多处发现含晚古生代放射虫硅质岩   总被引：21，自引：3，他引：21  

何科昭  周正国 《现代地质》1996,10(3):303-307,T001

作者继１９９３年１０月在赣东北蛇绿混杂岩带中首次发现晚古生代深水相放射虫硅质岩之后，经过１９９５年和１９９６年两次野外工作，又在该混杂岩带中及其两侧多处发现了含晚古生代放射虫的硅质岩及其深水相的沉积组合。从而为华南晚古生代或古生代—中生代洋盆的厘定，以及华南大地构造格局的再认识，提供了有力的新论据  相似文献   

四川北川桂溪地区晚志留亚纪地层的发现     

金淳泰  万正权  陈继荣  钱永蓁 《地球学报》1996,17(1):99-104

四川桂溪地区志田纪地层，于１９７０年由四川省地质局第二区调队发现，并根据其中所含腕足类Ｅｏｓｐｉｒｉｆｅｒｔｉｎｇｉ笼统划归中志留统。１９９４年，笔者等在这段地层中发现了以牙形石Ｓｐａｔｈｏｇｎａｔｈｏｄｕｓｃｒｉｓｐｕｓ，腕足类Ｒｅｔｚｉｅｌｌａｕｎｉｐｌｉｃａｔａ，床板珊瑚Ｓｑｕａｍｅｏｆａｖｏｓｉｔｅｓ，Ｏａｃｈｙｆａｖｏｓｉｔｅｓ，Ｐａｃｈｙｃａｎａｌｉｃｕｌａ为代表的晚志留亚纪动物属种，说明该套地层的沉积时限为晚志留亚纪，并可与云南曲靖，四川广元、二郎山、盐边，甘肃迭部等地区相当地层对比。这一发  相似文献   

青藏高原更新世晚期冰川的均衡效应     

汪汉胜  许厚泽 《测绘学报》1997,26(2):148-154

本文基于Ｋｕｈｌｅ关于青藏更新世晚期存在统一大冰盖的假说，构制冰负荷史模型，利用Ｐｅｌｔｉｅｒ（１９７４，１９７６）粘弹地球表面负荷形变理论，计算出冰盖负荷引起的地表垂直位移和重力变化，并将其作为该区冰种均衡效应的最大估计，数值计算结果表明，冰盖负荷的均衡作用对高原隆升有一定的影响。  相似文献   

Cretaceous episodic growth of the Japanese Islands   总被引：1，自引：0，他引：1  

G. Kimura 《Island Arc》1997,6(1):52-68

Abstract The Japanese Islands formed rapidly in situ along the eastern Asian continental margin in the Cretaceous due to both tectonic and magmatic processes. In the Early Cretaceous, huge oceanic plateaus created by the mid-Panthalassa super plume accreted with the continental margin. This tectonic interaction of oceanic plateau with continental crust is one of the significant tectonic processes responsible for continental growth in subduction zones. In the Japanese Islands, Late Cretaceous-Early Paleogene continental growth is much more episodic and drastic. At this time the continental margin uplifted regionally, and intra-continent collision tectonics took place in the northern part of the Asian continent. The uplifting event appears to have been caused by the subduction of very young oceanic crust (i.e. the Izanagi-Kula Plate) along the continental margin. Magmatism was also very active, and melting of the young oceanic slab appears to have resulted in ubiquitous plutons in the continental margin. Regional uplift of the continental margin and intra-continent collision tectonics promoted erosion of the uplifted area, and a large amount of terrigenous sediment was abruptly supplied to the trench. As a result of the rapid supply of terrigenous detritus, the accretionary complexes (the Hidaka Belt in Hokkaido and the Shimanto Belt in Southwest Japan) grew rapidly in the subduction zone. The rapid growth of the accretionary complexes and the subduction of very young, buoyant oceanic crust caused the extrusion of a high-P/T metamorphic wedge from the deep levels of the subduction zone. Episodic growth of the Late Cretaceous Japanese Islands suggests that subduction of very young oceanic crust and/or ridge subduction are very significant for the formation of new continental crust in subduction zones.  相似文献