Evidence for anisotropy in the super-thick sedimentary basin,Bay of Bengal     

James N. Brune  Govardhan Mekala  Yuehua Zeng 《Journal of Earth System Science》1995,104(1):L147-L155

Evidence for anisotropy in the super-thick sedimentary basin under the northern Bay of Bengal is presented. Surface wave group velocity data given by Brune and Singh (1986) is better fit by an anisotropic model than an isotropic one. This lends support to the hypothesis that the mid-crustal rocks are metasediments and that the section of sediments and metasediments is more than 20 km thick.  相似文献   

拉萨地块林周盆地下白垩统塔克那组：新特提斯洋活动陆缘伸展阶段沉积记录     

刘航宇  石开波  刘波  宋本彪  刘卓 《地质学报》2022,96(3):783-804

拉萨地块林周盆地下白垩统塔克那组沉积于新特提斯洋壳向拉萨地块俯冲的弧后伸展环境，对重构该时期古地理格局、理解活动陆缘伸展构造对沉积的控制作用具有重要意义。基于野外露头描述和薄片观察，总结塔克那组岩石地层、岩石学和古生物特征，对比同期新特提斯被动陆缘阿拉伯板块Shuaiba组，讨论塔克那组沉积演化和活动陆缘沉积特征。塔克那组发育碎屑岩、硅质碎屑- 碳酸盐混积岩、碳酸盐岩三大类沉积岩十种岩石类型，纵向上划分为四个岩性段，是一个三级相对海平面变化旋回的沉积层系。塔一段砂岩—混积岩—灰岩岩性变化、沉积构造和生物类型均指示潮间- 潮下带潟湖环境；塔二段沉积于海平面快速上升期，主要为风暴浪基面之下厚层泥灰岩；塔三段在玛行西剖面首次识别出代表风暴浪基面之上的风暴成因生物富集层，往西南在甲绒东剖面相变为浅滩相生屑/鲕粒颗粒灰岩；塔四段沉积期海平面持续下降，海水逐渐退出盆地，沉积滨岸和泛滥平原环境的泥页岩夹粉砂岩。与阿拉伯板块同期生物种属对比表明，塔克那组沉积期，南拉萨地块林周盆地与新特提斯洋沟通性好。活动陆缘伸展背景下，具有基底快速差异沉降、陆源沉积物持续输入的特征，导致纵、横向相变快，混积岩发育，厚壳蛤、Lithocodium- Bacinella等浅海喜净水生物和深水浮游生物欠发育。  相似文献   

The smallest of the largest: a new look at possible dwarfing in sauropod dinosaurs     

Jianu  Coralia-Maria  Weishampel  David B. 《Geologie en Mijnbouw》1999,78(3-4):335-343

Franz Baron Nopcsa recognised that the Late Cretaceous titanosaurid sauropod from Transylvania, Magyarosaurus dacus, was much smaller than the better known sauropods from the Upper Jurassic of the United States and even from Late Cretaceous deposits elsewhere in the world. In keeping with his biogeographic interpretations, Nopcsa viewed this difference as a consequence of body-size effects via island habitation. We present a preliminary re-evaluation of Nopcsa's claims and their heterochronic consequences using two approaches, viz. (1) regression analysis of humeral data as a means of establishing patterns in body size among titanosaurids, and (2) optimisation of humeral data onto titanosaurid cladograms to evaluate evolutionary trends within the clade. Our regression analysis is based on twenty species distributed among fourteen genera of neosauropods and uses length and mid-shaft mediolateral width of the humerus of presumed fully adult forms, and of growth samples that consist of postnatal to adult individuals. Linear regression analysis suggests that, among adult neosauropods, M. dacus appears to be represented by the smallest individuals; that M. dacus humeri appear to be more similar to those of subadults than to adults of other taxa; and that this juvenile morphology may constitute dwarfing in M. dacus by paedomorphosis. In order for these regressions to reflect their evolutionary context more fully, we also present optimisation analyses of humeral form within Titanosauroidea. Although many aspects of the phylogeny of this clade are relatively poorly resolved, preliminary results of our analyses are consistent with the conclusion that M. dacus was a heterochronic dwarf.  相似文献   

赣南—粤北版石群及其地质时代   总被引：11，自引：1，他引：10  

巫建华  张树明  周维勋 《地层学杂志》1999,23(3):226-233

赣南—粤北中生代晚期存在上、中、下3个不同时代的火山岩系,其中上火山岩系称为版石群。根据岩性岩相特征,版石群可进一步划分为两个岩组:下岩组称为合水组,以砾岩、砂岩、页岩等沉积岩为主、夹火山岩,代表火山活动初始期的产物;上岩组称为优胜组,岩性为流纹岩、流纹质凝灰岩、熔结凝灰岩,代表火山活动喷发期的产物。长塘盆地优胜组熔结凝灰岩全岩RbSr等时线年龄为89.5Ma;仁差盆地优胜组流纹岩全岩RbSr等时线年龄为91.9～94Ma,熔结凝灰岩锆石UPb法年龄为86.5Ma,次流纹斑岩锆石UPb法年龄为93.5Ma;菖蒲盆地优胜组流纹岩全岩RbSr等时线年龄为104Ma;版石盆地优胜组流纹岩全岩RbSr等时线年龄为72.2Ma,全岩KAr法年龄为77.6Ma,可见版石群优胜组的地质时代为早白垩世晚期—晚白垩世早期。另外,合水组的生物化石反映出早白垩世的特征,因此,将版石群置于早白垩世—晚白垩世早期是可信的。  相似文献   

化学地层学及其研究进展   总被引：2，自引：0，他引：2  

吴智勇 《地层学杂志》1999,23(3):234-240

化学地层学是利用岩层中化学元素及其化合物的演变规律及含量分布特征进行地层的划分和对比,进而推断地层形成时的地球化学环境的一门地层学分支。根据所采用的化学信号,化学地层学可进一步划分为放射性同位素地层学、稳定同位素地层学、分子化学地层学、有机碳和碳酸盐碳化学地层学和元素化学地层学等。  相似文献   

Discussion of “Challenges in operationalizing the water–energy–food nexus”*     

Olli Varis  Marko Keskinen 《水文科学杂志》2020,65(Z2):1863-1865

ABSTRACT

We greatly enjoyed reading the paper by Liu et al., which is both timely and rich in insight, as it discusses the challenges in operationalizing the water–energy–food security (WEF) nexus. The nexus approach is gaining increasing attention, both in research and in policy documents, as reflected in the number and content of published documents in the past years and highlighted by the authors.  相似文献   

A Palaeomagnetic Study of 143 Ma Kimberlite Dikes In Central New York State     

Mickey C. Van Fossen  Dennis V. Kent 《Geophysical Journal International》1993,113(1):175-185

  相似文献   

内蒙古平庄─元宝山盆地群晚中生代地层   总被引：2，自引：0，他引：2  

商平  王宇林 《地层学杂志》1994,18(4):275-281

平庄─元宝山盆地的晚中生代地层可划分为下白垩统黑水组、元宝山组和杏园组，上侏罗统上那不打组与那不打组。杏园组和元宝山组中含有丰富的植物化石，属于ＲｕｆｆｏｒｄｉａＯｎｙｃｈｉｏｐｓｉｓ植物群的中部组合，可与邻区的主要含煤沉积的植物组合进行对比，时代属早白垩世Ｂｅｒｒｉａｓｉａｎ期至早Ａｐｔｉａｎ期。  相似文献   

论山东东营、惠民盆地油田水与油气聚集关系   总被引：7，自引：2，他引：7  

李春光 《地质论评》1994,40(4):340-346

山东东营、惠民盆地的油源断裂,即沟通生油岩与非生油岩的同生断裂发育区,出现了油田水的高含盐度分布带。它不仅与已知油气藏的分布相一致,而且水的含盐度异常值与石油储量之间呈正相关。笔者以东辛、现河庄和临商油田为例,分析了油田水与油气藏形成的成因和伴生关系,还用相关曲线定量预测了盆地新区石油地质储量,并经钻探证实其可靠性。  相似文献   

福建浦城—三都澳火山喷发带早白垩世火山地层划分对比     

谢家莹  郑惠文 《福建地质》1994,13(1):26-36

本文根据浦城—三都澳火山喷发带早白垩世火山活动产物及其所组成的火山构造的解剖研究，在肯定或重新厘定各火山机构内的火山地层层序基础上，建立火山机构一火山岩相－火山地层模式，进行横向对比，阐明火山活动基本特征。  相似文献