湘鄂赣二叠纪岩相古地理研究   总被引：4，自引：0，他引：4  

牟传龙  丘东洲  王立全  万方 《沉积与特提斯地质》1997,17(6):1-21

湘鄂赣二叠纪沉积盆地是在华南陆块基础上发育而成，具有扬子克拉通北缘被动大陆边缘盆地，扬子克拉通盆地，湘赣板内拉张盆地和华夏克拉通边缘盆地等四类。根据古暴露等标志，建立了各类盆地的沉积层序，并进行了区域对比。  相似文献   

燕山地区印支期构造相研究     

陈正乐  杨农  陈宣华 《地球学报》1997,18(1):11-17

本文简单回顾了构造相的研究概况，分析了构造相的控制因素；笔者从岩石的能干性出发，提出了地层能干性的新概念，计算了燕山地区前中生代各地层的能干性和印支期变形的温压条件，并对燕山地区印支期构造相进行了系统的划发，建立了印支期的相结构。提出了本区印支期构造相以变流相为主的观点。  相似文献   

Timing and exhumation of eclogite facies shear zones, Musgrave Block, central Australia   总被引：2，自引：0，他引：2  

A. CAMACHO  W. COMPSTON  M. McCULLOCH  & I. McDOUGALL 《Journal of Metamorphic Geology》1997,15(6):735-751

Timing constraints on shear zones can provide an insight into the kinematic and exhumation evolution of metamorphic belts. In the Musgrave Block, central Australia, granulite facies gneisses have been affected, to varying degrees, by mylonitic deformation, some of which attained eclogite facies. The Davenport Shear Zone is a dominant strike-slip system that formed at eclogite facies conditions ( T  ≈650  °C and P ≈12.0  kbar). Sm–Nd mineral isochrons obtained from equilibrated high-pressure assemblages, as well as ⁴⁰Ar–³⁹Ar data, show that the eclogite and greenschist facies high-strain overprints were coeval, at c .  550  Ma. Mylonitic processes do not appear to have reset the U–Pb system in zircon, but may have partially disturbed it. The thermal gradient in the Musgrave Block crust at c .  550  Ma was c .  16  °C  km⁻¹ and at c .  535  Ma was c .  18  °C  km⁻¹, based on P – T  estimates of eclogite and greenschist facies shear zones, respectively. These estimates are similar to present-day geothermal gradients in many stable continental shield areas, suggesting that the region did not undergo a significant transient perturbation of the geotherm. Therefore, in the Musgrave Block, cooling subsequent to eclogite facies metamorphism appears to have been controlled by exhumation, rather than by the removal of a heat source. Estimated exhumation rates in the range 0.2 to ≥1.5  mm year⁻¹ are comparable with other orogenic belts, rather than cratonic areas elsewhere.  相似文献   

Comparison of source rock geochemistry of selected rocks from the Schei Point group and Ringnes formation, Sverdrup basin, arctic Canada     

P. K. Mukhopadhyay  F. Goodarzi  M. A. Kruge  M. H. Alimi 《International Journal of Coal Geology》1997,34(3-4)

Organic-rich from the Schei Point group (middle to late Triassic in age) and the Ringnes formation (late Jurassic) from the Sverdrup basin of the Canadian arctic archipelago have been geochemically evaluated for source rock characterization. Most samples from the Schei Point group are organic-rich (> 2% TOC and are considered as immature to mature oil-prone source rocks [kerogen types I, I–II (IIA) and II (IIA)]. These kerogen types contain abundant AOM1, AOM2 and alginite (Tasmanales, Nostocopsis, Leiosphaeridia, acritarch and dinoflagellate) with variable amounts of vitrinite, inertinite and exinite. Samples from the Ringnes formation contain dominant vitrinite and inertinite with partially oxidized AOM2, alginite and exinite forming mostly immature to mature condensate- and gas-prone source rocks [kerogen type II–III (IIB), III and a few II (IIA)]. Schei Point samples contain higher bitumen extract, saturate hydrocarbons and saturate/ aromatic ratio than the Ringnes samples. Triterpane and sterane (dominant C₃₀) distribution patterns and stable carbon isotope of bitumen and kerogen suggest that the analyzed samples from the Schei Point group are at the onset of oil generation and contain a mixture of sapropelic (algal) and minor terrestrial humic organic matter. Sterane carbon number distributions in the Ringnes formation also suggest a mixed algal and terrestrial organic matter type. There are some variations in hopane carbon number distributions, but these are apparently a function of thermal maturity rather than significant genetic differences among samples. Pyrolysis-gas chromatography/mass spectrometry of the two samples with similar maturity shows that the Schei Point sample generates three times more pyrolyzate than the Ringnes sample. Both samples have a dominant aliphatic character, although the Ringnes sample contains phenol and an aromaticity that is higher than that of the Schei Point sample.  相似文献   

中国南方晚二叠世乐平煤的成因及成煤物质     

陈能贵 《海相油气地质》1996,1(2):29-33,T001

乐平煤是分布于苏浙皖赣地区龙潭组中的特有煤种(俗称树皮煤),也是一种具良好生烃潜力的烃源岩。乐平煤中,壳质组和可溶有机质含量高,母质类型为高等植物和低等生物双重来源,元素组成具富氢、低氧、高含硫的特征,应属海相成因的泥炭坪沉积。成煤物质主要来源于真蕨、种子蕨和科达类等植物的树皮体。树皮体又可分为茎皮体和根皮体两种亚组分。依据煤的显微组分组成和树皮体富集程度的不同,乐平煤可分为原地型、过渡型和微异地型三种成因类型。乐平煤的研究对整个南方二叠纪煤成烃资源的评价具重要的地质意义。  相似文献   

新疆阿合勒－冲乎尔地区泥盆纪相动力学研究     

牟传龙  刘宝珺  朱晓镇 《沉积与特提斯地质》1996,(3)

阿合勒－冲乎尔火山沉积盆地是一个以火山岩并伴有陆源和内源沉积物的堆积场所，即该区泥盆纪地层是以事件作用的产物为其主要成分特点。显然，对其古地理的恢复、相的划分采用传统的相序分析方法是不合适的。作者认为要阐明该区泥盆纪的古地理面貌，必须在区域地层研究基础上，综合分析各种相标志和沉积物的特点，寻求它们的物理成因和地质成因解。在这一过程中，相的动力学分析显得尤为重要。本文在上述学术思想指导下，把本区泥盆纪的相分为成因相和环境相两大类，并对其中的微相进行了详细的阐述，从而为把沉积学的原理和方法应用了火山岩的搬运机制和堆积环境研究中提供了先期研究实例，同时为研究和恢复该区以至整个新疆北部泥盆纪的古地理格局打下了坚实的基础。  相似文献   

一种分析砂岩沉积相的新方法——测井相分析   总被引：5，自引：0，他引：5  

李军  王贵文 《地质论评》1996,42(5):443-447

本文分析了以地层倾角测井资料为核心的各种测井相标志，提出了应用测井资料进行沉积相分析的方法和步骤，并在塔里木盆地三个油田进行了测井地质相分析。  相似文献   

The Silurian of Gotland (Sweden): facies interpretation based on stable isotopes in brachiopod shells     

Chr Samtleben  A. Munnecke  T. Bickert  J. Pätzold 《International Journal of Earth Sciences》1996,85(2):278-292

The Silurian of Gotland, Sweden, consists of 440 m of carbonate deposits. Repeatedly, uniform sequences of micritic limestones and marls are interrupted by complex-structured reefs and by adjacent platform sediments. Generally, the alteration of facies is interpreted as the result of sea-level fluctuations caused by a gradual regression with superimposed minor transgressive pulses. The purpose of this study is a facies interpretation based on both field observations and stable isotope measurements of brachiopod shells. Approximately 700 samples from stratigraphically arranged localities in different facies areas have been investigated. The carbon and oxygen isotopes show principally parallel curves and a close relationship to the stratigraphic sequence. Lower values occur in periods dominated by deposition of marly sequences. Higher values are observed in periods dominated by reefs and extended carbonate platforms. The oxygen isotope ratios are interpreted to reflect paleosalinity changes due to varying freshwater input, rather than to paleotemperature. Carbon isotope ratios are believed to have been connected to global changes in the burial of organic carbon in black shales during periods of euxinic deep water conditions. Consequently, the facies succession on Gotland results from global paleoclimatic conditions. Changes in terrigenous input due to different rates of weathering and freshwater runoff, rather than sea-level fluctuations, control the carbonate formation of the Silurian on Gotland.  相似文献   

海州式磷矿床地质特征及其成矿模式   总被引：2，自引：0，他引：2  

熊先孝  姚超美 《矿床地质》1996,15(2):171-181

海州式磷矿成矿物质有多种来源。磷元素在地壳发展过程中，随着磷矿成矿作用不同阶段物化条件等改变而变化，将成矿划分为沉积、变质及改造三阶段。中元古代早期海州群锦屏组，肥东群双山 ，宿松群柳坪组和虎踏石组及红安群七角山组下段为其“源”，磷块岩形成后，由于变质、混合岩化交代和风化淋滤作用，使磷质活化，在一定的空间富集成矿。  相似文献   

谈调整构造   总被引：7，自引：1，他引：7       下载免费PDF全文

燕守勋  孟宪刚 《地质科学》1997,32(2):146-155

调整构造是伸展型沉积盆地和造山带中普遍存在的构造,它与走向构造一起,控制了沉积盆地或造山带的基本轮廓与内部结构。调整构造横切走向构造,并与之共同控盆、控岩、控矿,并间隔开两侧不同的构造样式。它以长时期、多阶段活动,具有高渗透性为主要特征,是控制矿带展布与矿床就位的重要构造,也是固定成矿预测区与找矿靶区的重要依据之一,本文以鲁西、中亚及乌拉山-大青山地区、兰坪─思茅盆地区及右江盆地区为例,论述了调整构造的基本特征及控矿作用。  相似文献