浙江前寒武纪超基性岩和古构造格局分划     

朱平 《浙江国土资源》1998,(2)

沿浙江诸暨石角、陈察分布的前寒武纪超基性岩分别为绍兴一江山对接带古洋壳下覆含水地促残留作和华夏古地体原始地侵高温底辟侵入体。两地超基性岩结构构造的独特性,与所处古地质构造单元之间推覆超法的运动学性质有关。岩体在地质特征和宕石化学、矿物化学等的明显差异,以及由此引致的特殊的成因条件,是分划两个不同古地质构造单元的依据：石角、陈蔡超基性岩体,应分别属于不同威尔逊旋回,同一俯冲阶段的前寒武纪上地幔深部成因的侵入岩。  相似文献   

电测深在康定白土坎滑坡勘查中的应用   总被引：1，自引：0，他引：1  

唐声海 《四川地质学报》1997,(4)

在白土坎滑坡勘察中，采用电测深来探测滑体结构、滑床形态及古拉裂其效果较好，为正确评价古滑坡的稳定性提供了较为充分的依据。  相似文献   

Paleoceanographic changes at the Jurassic–Cretaceous boundary in the Western Tethys, northeastern Mexico     

Thierry Adatte  Wolfgang Stinnesbeck  Jürgen Remane  Hans Hubberten 《Cretaceous Research》1996,17(6):671-689

Mexico is usually considered to have formed the western end of the Tethys during Late Jurassic and Early Cretaceous times. The circumstances of the opening of the Gulf of Mexico Basin towards the Tethys and the exact stratigraphic timing, however, are not clear. Four sections covering this time interval, located in northeastern Mexico, have been measured and sampled in detail, in order to clarify their stratigraphic position during the Late Jurassic to Early Cretaceous time interval and the paleogeographic and oceanographic changes that accompanied this opening. Our studies include microfacies, micro- and macropaleontology, whole rock and clay-mineral x-ray diffraction and stable isotopes analyses. Our data indicate that the Jurassic-Cretaceous boundary, as defined by the Lyon-Neuchâtel Colloquium of 1973, cannot be determined precisely in northeastern Mexico due to the near-absence of calpionellids and endemism of ammonite taxa. In the lower and upper Berriasian sediments, we detected Mediterranean ammonite taxa so far unknown from Mexico, corresponding to the appearance of typical calpionellid-rich facies. These faunas allow direct biostratigraphic correlation with European ammonite and calpionellid zones.We propose that a major oceanographic change occurred in the upper part of calpionellid Zone B of the Early Berriasian. At this time, sediments in northeastern Mexico present increasingly pelagic facies, a dramatic appearance of Tethyan microfossils (calpionellids) and ammonites, changes in stable isotopic values, whole rock and clay-mineral mineralogy. We suggest that these changes are due to a global sea-level rise that connected directly northeastern Mexico to the European Tethys and ended the endemic, semi-restricted and anoxic environment of the Late Jurassic La Casita and equivalent La Caja and La Pimienta Formations.  相似文献   

东特提斯多弧一盆系统演化模式   总被引：8，自引：2，他引：8       下载免费PDF全文

潘桂棠  陈智樑  李兴振  徐强  江新胜 《沉积与特提斯地质》1996,16(2):52-65

自７０年代以来，以板 构造观点分析特提斯演化已有三种模式，即“剪刀张”、“传送带”和“手风琴运动与开合”模式。所有这些模式都是以一个联合古陆的形成和特提斯是泛大洋中一个海湾的假设为前提，或以冈瓦纳大陆裂离、亚洲大陆增生为基点。随着对东特提斯地质构造演化的认识深化，特提斯演化、造山作用的解释由两陆一洋模式转变为三陆群二洋的特提斯多弧－盆系统洋陆转换演化模式，即多岛弧造山模式。  相似文献   

Ophiolites from the Mianlue Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution     

LAI Shaocong  ZHANG Guowei  LI SanzhongKey Laboratory of Continental Dynamics  Ministry of Education  Department of Geology  Northwest University  Xi''an  Shaanxi  College of Earth Science  Ocean University of Qingdao  Qingdao  Shandong 《《地质学报》英文版》2004,78(1)

The Mianlue suture extends from Derni-Nanping-Pipasi-Kangxian to the Lueyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melange associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianliie paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.  相似文献   

祁连党河南山北坡中-基性火山岩地质特征及时代   总被引：3，自引：0，他引：3  

李厚民  王崇礼  刘继庆  刘志武  沈远超 《矿物岩石》2003,23(1):1-4

根据地质研究、区域对比，结合首次获得的Rb-Sr等时线年龄数据，从祁连党河南山(又称乌兰达坂山）北坡原中奥陶统地层中厘定出晚震旦纪中－基性火山岩系。根据这一新成果，认为该区中基性火山岩，斜长角闪岩基底以及侵入其中的扎子沟等花岗闪长岩岩基在大地构造分区上应划归中祁连地块；晚震旦纪该区无疑有过扩张、地壳减薄的地质事件，震旦纪晚期有过挤压闭合事件。  相似文献   

方解石和白云石溶蚀实验热力学模型及地质意义   总被引：15，自引：0，他引：15  

肖林萍  黄思静 《矿物岩石》2003,23(1):113-116

通过碳酸盐（方解石、白云石）溶蚀作用实验室模拟研究，建立了溶蚀作用的热力学模型方程，对埋藏成岩的3种不同温压条件下（348．15K，Mpa ,373．15K，25Mpa，403．15K，30MPa）碳酸盐溶蚀作用进行了定量研究。提出随着温度和压力的升高，碳酸盐溶解反应的吉布春播由能降低，因而溶解反应增强；在相同温度和压力的地质条件下，白云石较方解石更易溶蚀并形成次生孔隙，这为油气生成运移提供了有利的地下空间和通道。  相似文献   

新金厂金矿床地球化学异常模式   总被引：1，自引：0，他引：1  

韦学团  赵秉玲 《地质与勘探》2002,38(2):33-36

初步探讨了新老金厂矿床地质地球化学，地球化学异常及其垂向分带特征，归纳出该矿床的地球化学异常模式和找矿标志。  相似文献   

Cretaceous volcanic rocks of the South Tethyan suture zone, Pakistan: implications for the Réunion hotspot and Deccan Traps   总被引：1，自引：0，他引：1  

J.J. Mahoney  R.A. DuncanW. Khan  E. GnosG.R. McCormick 《Earth and Planetary Science Letters》2002,203(1):295-310

The location, ages, and geochemical characteristics of marine volcanic rocks preserved in the South Tethyan suture zone of Pakistan suggest that the Réunion hotspot was active off northwestern Greater India well before the emplacement, far to the south, of the Deccan flood basalts, the great bulk of which were erupted at 65-66 Ma and are widely believed to be associated with the hotspot’s plume-head phase. Most of the suture zone samples have Nd-Pb-Sr isotopic ratios (e.g. age-corrected ?_Nd(t)=+3.0 to +4.6) close to those expected for modern-type Réunion source mantle in the Late Cretaceous, and their incompatible element patterns resemble those of recent Réunion shield lavas. ⁴⁰Ar-³⁹Ar incremental heating yields ages of 73.4-72.0 Ma. Nevertheless, unless even older ages are discovered among the suture zone rocks, a pre-Deccan marine phase of Réunion hotspot activity on the Tethyan side of Greater India can be accommodated within the framework of the plume-head model.  相似文献   

Was there a wind-driven Tethys circumglobal current in the Late Cretaceous?     

N.M.M. Cousin-Rittemard  H.A. DijkstraT. Zwagers 《Earth and Planetary Science Letters》2002,203(2):741-753

The problem of the existence of a Tethys circumglobal current (TCC) in the Late Cretaceous continental geometry (Campanian) is addressed. Within an ocean model which is expected to strongly overestimate the wind-driven TCC volume transport, a relatively weak TCC is found for the reconstructed Campanian paleogeography used. As a measure of the strength of the TCC, a circumglobal flow index is introduced. This index is based on volume fluxes through meridional sections within the equatorial part of the domain. The impact of changes in the paleogeography on the TCC is considered by computing steady flows for different shapes of Eurasia. The results on the extent of Eurasia such that a strong TCC appears provide support that no strong wind-driven TCC has existed during the Campanian.  相似文献