Bioistratigraphical and sedimentological study of Upper Senonian–Lower Eocene sediments of Tripolitza Platform in central Crete (Greece)     

A. Zambetakis-Lekkas  F. Pomoni-Papaioannou  A. Alexopoulos 《Cretaceous Research》1998,19(6):715-732

The stratigraphic and palaeoenvironmental implications of a section in the Upper Senonian to Lower Eocene carbonates of the Tripolitza Platform in central Crete are discussed in this paper. The lower part (upper Campanian–lower Maastrichtian) of the succession consists of about 75 m of thickly bedded, light to dark grey limestones, dolomitic limestones and dolomites that were deposited on an inner carbonate platform. It is characterized by stratified bioclastic rudist facies (shelly limestone) associated with foraminifera and especially with species of the Rhapydioninidae family. These are overlain by 35 m of crystalline light grey dolomites that were deposited on a very restricted internal platform, characterized by intertidal-supratidal facies. The overlying 75-m-thick light grey dolomitic limestones and dolomites are characterized by the presence ofRhapydionina liburnicaStache, and in the uppermost part byNeobalkhania bignotiCherchi, Radoicic & Schroeder, dating it as Late Maastrichtian. The facies, cryptalgal laminites with fenestrae of varying dimensions, suggest relatively extensive subaerial exposure. Possible pedogenic textures are common in this sequence and especially in the uppermost part, which coincides with the K/T boundary. The presence ofPseudonummoloculina heimi(Bonet) at two levels in the Maastrichtian succession suggests transportation of Middle-Late Cenomanian sediments from emergent blocks of the platform during this period. A gap is suspected, for regional stratigraphic reasons, between this horizon and the next which containsSpirolinasp. and “Pseudochrysalidina” sp., dating it as Early-Middle Eocene.  相似文献   

华山——熊耳山地块早前寒武纪绿岩及其形成构造背景     

刘红樱  陈衍景 《地质论评》1998,44(3):233-242

华北地台南缘华山－熊耳山地块早前寒武纪绿岩带中存在有晚太古代第一期绿岩和古元古代早期第二期绿岩。它们的地质地球化学特征的研究表明：第一期绿岩为一套大洋型基性－中酸性火山岩和科马提岩类夹少量典型太古宙深海沉积建造,形成于硅镁质地壳拉开背景下的洋中脊环境,代表当时的洋壳;第二期绿岩为一套岛弧型基性－中基性火山岩夹中酸性火山岩、下部的太古宙型沉积岩和上部的后太古宙型沉积岩,形成于第一期绿岩硅铝化而成的岛  相似文献   

New Paleomagnetic Study on Early Triassic Liujiagou Formation of North China Block *     

Tian Wuhong Faculty of Earth Sciences  China University of Geosciences  Wuhan Niu Xiukai Hebei Bureau of Geology  Mineral Resources  Shijiazhuang 《中国地质大学学报(英文版)》1998,(3)

ＩｔｉｓｋｎｏｗｎｔｏｕｓｔｈａｔｔｈｅｔｉｍｅａｎｄｓｔｙｌｅｏｆｃｏｌｉｓｉｏｎｏｆＮｏｒｔｈＣｈｉｎａｂｌｏｃｋ（ＮＣＢ）ｗｉｔｈＹａｎｇｔｚｅｂｌｏｃｋ（ＹＢ）ａｒｅｒｅｌａｔ－ｅｄｔｏｔｈｅｔｅｃｔｏｎｉｃｅｖｏｌｕｔｉｏｎｏｆＱｉｎｌｉｎ...  相似文献   

临夏盆地早更新世东山古湖沉积的高分辨率气候记录   总被引：3，自引：0，他引：3  

王建力  李吉均 《地理科学》1998,18(4):349-354

临夏盆地东山古湖（２．３５～１．６５ＭａＢ．Ｐ．）沉积厚达８４ｍ,是六盘山以西早更新世湖相沉积的典型代表。以２．５ｍ的间隔对其进行系统采样,以ＣａＣＯ３含量变化为指标建立高分辨率的气候变化曲线,对曲线进行周期分析表明,东山古湖所反映的气候波动具有明显的４１０００ａ主导周期;其中２．２８ＭａＢ．Ｐ．和１．７５～１．８０ＭａＢ．Ｐ．时段为两个明显的冷湿时期,表明东亚季风在建立初期具有不稳定性。  相似文献   

湘桂早海西期构造层序地层与板内构造运动   总被引：2，自引：0，他引：2  

杨明慧 《湖南地质》1998,17(1):14-18

该文在分析地层界面性质的基础上建立了湘桂地区早海西阶段的构造层序地层格架,并据此探讨了研究区早海西阶段的板内伸展裂陷活动及晚期的板内软碰撞以及软碰撞带对湘中同沉积外生矿产的控制意义。  相似文献   

胜利海上埕岛油田下古生界潜山高产因素分析   总被引：1，自引：0，他引：1  

高喜龙  杨鹏飞 《海相油气地质》1998,3(4):51-56

埕岛油田是我国浅海－极海海域发现的第一个大型整流油气田,四周环凹,油源条件十分优越,全区可划分为西排山,中排山,东排山三个潜山带构造单元,油气运移通道主要是断裂和风化壳不整合面,区域盖层发育良好,储集条件是油气富集高产控制因素,纵向上潜山带储层主要集中在潜山的风化壳;平面上主要沿断层分布,沿断层发育的奥陶系在潜山是本区古生办潜山勘探的最有利目标。  相似文献   

Lateglacial and early Holocene dynamics of adjacent valley glaciers in the Western Swiss Alps     

Inga Schindelwig  Naki Akçar  Peter W. Kubik  Christian Schlüchter 《第四纪科学杂志》2012,27(1):114-124

The Alps play a pivotal role for glacier and climate reconstructions within Europe. Detailed glacial chronologies provide important insights into mechanisms of glaciation and climate change. We present 26 ¹⁰Be exposure dates of glacially transported boulders situated on moraines and ice‐moulded bedrock samples at the Belalp cirque and the Great Aletsch valley, Switzerland. Weighted mean ages of ～10.9, 11.1, 11.0 and 9.6 ka for the Belalp, on up to six individual moraine ridges, constrain these moraines to the Egesen, Kartell and Schams stadials during Lateglacial to early Holocene times. The weighted mean age of ～12.5 ka for the right‐lateral moraine of the Great Aletsch correlates with the Egesen stadial related to the Younger Dryas cooling. These data indicate that during the early Holocene between ～11.7 and ～9.2 ka, glaciers in the Swiss Alps seem to have been significantly affected by cold climatic conditions initiated during the Younger Dryas and the Preboreal Oscillation. These conditions resulted in glacier margin oscillations relating to climatic fluctuations during the second phase of the Younger Dryas – and continuing into Boreal times – as supported by correlation of the innermost moraine of the Belalp Cirque to the Schams (early) Holocene stage. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Early Pleistocene palaeoenvironments at the time of the Homo antecessor settlement in the Gran Dolina cave (Atapuerca,Spain)     

HUGUES‐ALEXANDRE BLAIN  GLORIA CUENCA‐BESCÓS  FRANCESC BURJACHS  JUAN MANUEL LÓPEZ‐GARCÍA  IVÁN LOZANO‐FERNÁNDEZ  JORDI ROSELL 《第四纪科学杂志》2013,28(3):311-319

  相似文献   

Zircon ages and geochemical compositions of the Manlay ophiolite and coeval island arc: Implications for the tectonic evolution of South Mongolia     

《Journal of Asian Earth Sciences》2014

Numerous small dismembered ophiolite fragments occur in South Mongolia, but they are very poorly studied. The lack of age data and geochemical analysis hampers our understanding of the Paleozoic tectonic evolution of the region. We conducted detailed studies on the Manlay ophiolitic complex and Huree volcanic rocks south of the Main Mongolian Lineament (MML) to provide some constraints on these rocks. The Manlay ophiolite consists of dunite, harzburgite, pyroxenite, gabbro, plagiogranite, basalt and chert, locally with chromite mineralization in dunite. The gabbro and plagiogranite yielded SHRIMP zircon weighted mean ²⁰⁶Pb/²³⁸U ages of 509 ± 5 Ma and 482 ± 4 Ma, respectively. The basalt and dolerite samples of this complex show enrichment in LREE and LILE and negative Nb, Ta and Ti anomalies, and the chrome spinel from the chromitite lens in the dunite is characterized by high Cr^# and low TiO₂ contents. These features suggest a supra-subduction zone (SSZ) origin for the ophiolitic complex. The Huree volcanic rocks, ranging from basalt to dacite, display enrichment in LREE and LILE, weak Eu anomalies and distinctly negative Nb, Ta and Ti anomalies, consistent with those of typical magmas in a subduction environment. An andesite sample from this arc yielded a SHRIMP ²⁰⁶Pb/²³⁸U zircon age of 487 ± 5 Ma, which is the oldest reliable age for an island arc in South Mongolia. Recognition of an Early Paleozoic ophiolitic complex and a coeval island arc indicates that South Mongolia underwent a period of active volcanism during Late Cambrian to Ordovician. Additionally, the tuff overlying the ophiolitic complex and a granite intruding the ophiolite have SHRIMP zircon U–Pb ages of 391 ± 5 Ma and 304 ± 4 Ma, respectively. Combining the available data, we propose that the Early Paleozoic subduction–accretionary complexes likely constitute the basement of the Late-Paleozoic arc formations and correlate with the Lake Zone in western Mongolia.  相似文献   

一次早台风暴雨的湿位涡分析     

罗艳艳  黄丽娜 《海洋预报》2008,25(1):102-110

0601号强台风"珍珠"是1949年以来5月份登陆我国最强的台风之一,与西风带系统在低纬度相互作用是早台风的预报要点.通过台风暴雨过程的湿位涡(MPV)分析,从湿位涡和湿位涡平流的的角度探讨西风带系统在早台风暴雨中的作用.结果表明:对流层中高层冷空气以漏斗状高MPV1柱的形式在江淮地区的维持及漏斗底部正MPV1向南入侵强台风环流,触发不稳定能量储存和释放,是此次早台风暴雨强度大的重要原因,同时也是台风登陆后迅速填塞,降水快速减弱的重要因素之一.正MPV2中心与暴雨中心有较好的对应.MPV2平流与MPV1平流量级相当,湿斜压作用与正压作用同样重要.  相似文献