Cambrian- Ordovician Deep - Water Deposits in Southwest Jiangxi, China     

Ji LeiNanjing Institute of Geography  Limnology  Academia Sini  Nanjing Jiang Minxi 《《地质学报》英文版》1994,68(4):435-449

The Cambrian-Ordovician rocks in southwestern Jiangxi are mainly composed of deep-water deposits, in which 5 facies have been recognized: sandstone facies, sandstone-mudstone facies, siltstone-mudstone facies, mudstone (slate)facies, and chert facies. They are of turbidity current origin and are related to pelagic and hemipelagic deposits. In the light of facies distribution, the Cambrian-Ordovician deposits can be classified into 3 facies associations formed in middle fan, outer fan and deep-sea plain environments respectively. The 3 different orders of vertical cycles in the stratigraphic sequence are considered to be controlled by factors such as sea-level fluctuation, basin subsidence and submarine fan progradation. The tectonic setting of the sedimentary basin is interpreted as passive continental margin based on the chemical composition analysis of the sandstone.  相似文献   

鄂尔多斯盆地东南部三叠系延长组一段湖相浊积岩特征及意义   总被引：10，自引：1，他引：10       下载免费PDF全文

王起琮  李文厚  赵虹  王岚  屈红军 《地质科学》2006,41(1):54-63,I0003

鄂尔多斯盆地东南部三叠系延长组一段湖相浊积岩主要分布于子长县寺湾和横山县庙沟等地区,位于长一段上部。岩石类型包括:块状砂岩,近基的中细粒砂岩,远基的粉砂岩及细砂岩,不规则砂、泥岩互层和深湖相泥岩。据岩石组合类型将该浊积扇划分为上扇和中扇,其沉积序列为向上粒度变粗、砂层变厚的进积型浊积扇沉积序列。根据底部印模构造指向,物源区大致位于研究区的北东。本文总结了浊积扇的演化,探讨了该浊积扇的发现对于认识区域构造背景及油气勘探的意义。  相似文献   

青海省曲麻莱地区巴颜喀拉山群浊积岩系识别的古遗迹学标志   总被引：1，自引：0，他引：1  

赵小明  焦明路  牛志军 《华南地质与矿产》2006,(3):48-54

青海南部曲麻莱-治多地区位于青藏高原东北部,广泛出露上三叠统巴颜喀拉山群砂板岩,地层厚度巨大,实体化石稀少,遗迹化石丰富.在1/25万区域地质调查过程中,我们收集了大量的基础资料,本文重点研究遗迹化石的保存状态、形态类型、生态习性及其在地层序列中的分布特征,结果表明:研究区内巴颜喀拉山群为半深海-深海环境下形成的浊积岩系,这与沉积学、岩石学的研究结果相一致.  相似文献   

Lithofacies and origin of late Quaternary mass transport deposits in submarine canyons, central Scotian Slope, Canada   总被引：2，自引：1，他引：2  

KIMBERLEY A. JENNER  DAVID J. W. PIPER  D. CALVIN CAMPBELL  DAVID C. MOSHER 《Sedimentology》2007,54(1):19-38

Mass transport deposits, up to 3·9 m thick, have been identified from piston cores collected from canyon floors and inter-canyon ridges on the central Scotian Slope. These deposits are characterized by four distinct mass-transport facies – folded mud, dipping stratified mud, various types of mud-clast conglomerate, and diamicton. Commonly, the folded and stratified mud facies are overlain by mud-clast conglomerate, followed by diamicton and then by turbidity current deposits of well-sorted sand. Stratified and folded mud facies were sourced from canyon walls. Overconsolidation in clasts in some mud-clast conglomerates indicates that the source sediment was buried 12–33 m, much deeper than the present cored depth, implying a source in canyon heads and canyon walls. The known stratigraphic framework for the region and new radiocarbon dating suggests that there were four or five episodes of sediment failure within the past 17 ka, most of which are found in more than one canyon system. The most likely mechanism for triggering occasional, synchronous failures in separate canyons is seismic ground shaking. The facies sequence is interpreted as resulting from local slides being overlain by mud-clast conglomerate deposits derived from failures farther upslope and finally by coarser-grained deposits resulting from retrogressive failure re-mobilizing upper slope sediments to form debrisflows and turbidity currents.  相似文献   

Sedimentological and marine eogenetic control on porosity distribution in Upper Cretaceous carbonate turbidites (central Albania)   总被引：1，自引：0，他引：1  

B. DEWEVER  L. BREESCH  A. MEZINI†  R. SWENNEN 《Sedimentology》2007,54(2):243-264

Results of a detailed petrographic and stable isotope study illustrate that sedimentological differences and eogenetic dissolution/precipitation processes controlled porosity distribution within carbonate turbidites of the Ionian basin (central Albania). Based on lithology characteristics and porosity distribution observed in outcrop, individual turbidite beds can be subdivided into four distinct intervals, i.e. from base to top: (A) a non‐porous wackestone/floatstone or packstone followed by (B) porous packstone–grainstone that grades into (C) wackestone and (D) non‐porous mudstone with pelagic foraminifera. Wackestone interval C is characterized by an alternation of porous and non‐porous laminae. Changes in turbidity current flow regime controlled the initial presence of matrix micrite giving rise to both matrix‐ and grain‐supported lithologies within turbidite sequences. These are non‐porous and porous, respectively. Four eogenetic diagenetic processes (dissolution, cementation, neomorphism and compaction) acted shortly after deposition and modified primary porosity characteristics and distribution. Alteration by meteoric water is excluded based on the continuous burial until the Oligocene of the studied deep marine carbonates. Moreover, the stable isotope data with values between −2·1‰ and +0·7‰ for δ¹⁸O_V‐PDB and between +1‰ and +3‰ for δ¹³C_V‐PDB, favour alteration by marine‐derived pore‐waters. Compaction and aggrading neomorphism occurred dominantly in intervals characterized by higher matrix micrite content, i.e. the floatstone base and the wackestone–mudstone upper turbidite part. Framework‐stabilizing cementation occurred dominantly in the packstone–grainstone middle part of the turbidite beds. In the latter porous lithologies, matrix micrite was not compacted because of the grain fabric and the framework‐stabilizing cements. Here, neomorphism of micrite into microrhombic euhedral calcite occurred and microporosity was preserved.  相似文献   

黑龙江省奥陶纪浊积岩及金矿床找矿远景     

浦全生  梁科伟  梁福来 《世界地质》2007,26(2):173-179

以多宝山—罕达气地区为例阐述了黑龙江省奥陶纪浊积岩及特征,并与国外典型浊积岩金矿床对比。指出该区曾处于西伯利亚板块和中朝板块之间的早古生代褶皱带,呼玛县兴隆地区和黑河市罕达气地区处于西伯利亚板块南缘的弧间盆地或弧后盆地,奥陶纪浊积岩十分发育,具有浊积岩型金矿床容矿岩石的典型特征;本文以省内浊积岩分布区金矿为实例,说明该地区将成为奥陶纪浊积岩金矿床的找矿远景区。  相似文献   

Hyperpycnal delivery of sand to the continental shelf: Insights from the Jurassic Lajas Formation,Neuquén Basin,Argentina     

《Sedimentology》2018,65(6):2149-2170

Hyperpycnal currents are river‐derived turbidity currents capable of transporting significant volumes of sediment from the shoreline onto the shelf and potentially further to deep ocean basins. However, their capacity to deposit sand bodies on the continental shelf is poorly understood. Shelf hyperpycnites remain an overlooked depositional element in source to sink systems, primarily due to their limited recognition in the rock record. Recent discoveries of modern shelf hyperpycnites, and previous work describing hyperpycnites deposited in slope or deep‐water settings, provide a valuable framework for understanding and recognizing shelf hyperpycnites in the rock record. This article describes well‐sorted lobate sand bodies on the continental shelf of the Neuquén Basin, Argentina, interpreted to have been deposited by hyperpycnal currents. These hyperpycnites of the Jurassic Lajas Formation are characterized by well‐sorted, medium‐grained, parallel‐laminated sandstones with hundreds of metre extensive, decimetre thick beds encased by organic‐rich, thinly laminated sandstone and siltstone. These deposits represent slightly obliquely‐migrating sand lobes fed by small rivers and deposited on the continental shelf. Hyperpycnites of the Lajas Formation highlight several unique characteristics of hyperpycnal deposits, including their distinctively thick horizontal laminae attributed to pulsing of the hyperpycnal currents, the extraction of coarse gravel due to low flow competence, and the extraction of mud due to lofting of light interstitial fluid. Recognition of shelf hyperpycnites in the Lajas Formation of the Neuquén Basin allows for a broader understanding of shelf processes and adds to the developing facies models of hyperpycnites. Recognizing and understanding the geometry and internal architecture of shelf hyperpycnites will improve current understanding of sediment transfer from rivers to deeper water, will improve palaeoenvironmental interpretations of sediment gravity‐flow deposits, and has implications for modelling potentially high‐quality hydrocarbon reservoirs.  相似文献   

东营河125断层几何学特征及其对浊积扇和油藏的控制作用   总被引：1，自引：0，他引：1  

王志坤  钟建华  艾合买提江·阿布都热合曼  高玉飞 《地球学报》2008,29(1):95-102

通过对河125断层几何学特征的分析发现弧形断裂平行于断层走向剖面上表现为断槽、断脊组合;垂直于断层走向剖面上断层分为竖滑段、倾滑段和平滑段3段,生长指数规律为弧中大于弧翼,断层倾角规律为弧中小于弧翼.断裂的几何学特征与运动学特征具有相关性.断层几何学特征对浊积扇具有重要的控制作用:平面上,弧中位置浊积扇最发育,弧翼为不同浊积扇的分界线;断槽为浊积砂体的补给通道,断脊为扇体不同补给区的分水岭;垂向上,倾滑段下部发育远岸浊积扇,中上部发育滑塌浊积岩,形成典型的弧扇对应现象.断层对油藏的控制表现为:控制储层展布、改善储层物性、沟通油源和形成生长背斜及断鼻油气藏.  相似文献   

Current‐aligned dewatering sheets and ‘enhanced’ primary current lineation in turbidite sandstones of the Marnoso‐arenacea Formation          下载免费PDF全文

Lawrence A. Amy  Peter J. Talling  Esther J. Sumner  Giuseppe Malgesini 《Sedimentology》2016,63(5):1260-1279

Turbidite sandstones of the Miocene Marnoso‐arenacea Formation (northern Apennines, Italy) display centimetre to decimetre long, straight to gently curved, 0·5 to 2·0 cm regularly spaced lineations on depositional (stratification) planes. Sometimes these lineations are the planform expression of sheet structures seen as millimetre to centimetre long vertical ‘pillars’ in profile. Both occur in the middle and upper parts of medium‐grained and fine‐grained sandstone beds composed of crude to well‐defined stratified facies (including corrugated, hummocky‐like, convolute, dish‐structured and dune stratification) and are aligned sub‐parallel to palaeoflow direction as determined from sole marks often in the same beds. Outcrops lack a tectonic‐related fabric and therefore these structures may be confidently interpreted to be sedimentary in origin. Lineations resemble primary current lineations formed by the action of turbulence during bedload transport under upper stage plane bed conditions. However, they typically display a larger spacing and micro‐topography compared to classic primary current lineations and are not associated with planar‐parallel, finely laminated sandstones. This type of ‘enhanced lineation’ is interpreted to develop by the same process as primary current lineations, but under relatively high near‐bed sediment concentrations and suspended load fallout rates, as supported by laboratory experiments and host facies characteristics. Sheets are interpreted to be dewatering structures and their alignment to palaeoflow (only noted in several other outcrops previously) inferred to be a function of vertical water‐escape following the primary depositional grain fabric. For the Marnoso‐arenacea beds, sheet orientation may be linked genetically to the enhanced primary current lineation structures. Current‐aligned lineation and sheet structures can be used as palaeoflow indicators, although the directional significance of sheets needs to be independently confirmed. These indicators also aid the interpretation of dewatered sandstones, suggesting sedimentation under a traction‐dominated depositional flow – with a discrete interface between the aggrading deposit and the flow – as opposed to under higher concentration grain or hindered‐settling dominated regimes.  相似文献   

Stratal composition and stratigraphic organization of stratal elements in an ancient deep‐marine basin‐floor succession,Neoproterozoic Windermere Supergroup,British Columbia,Canada          下载免费PDF全文

Viktor Terlaky  Jonathan Rocheleau  Robert William Charles Arnott 《Sedimentology》2016,63(1):136-175

Despite a globally growing seismic and outcrop analogue data set, the detailed (centimetre to decametre) internal stratal make up of deep‐marine basin‐floor ‘channelized‐lobe’ strata remain poorly known. An ancient analogue for modern, mixed‐sediment, passive margin, deep‐marine basin‐floor fans is the well‐preserved Neoproterozoic Upper and Middle Kaza groups in the southern Canadian Cordillera. This succession is a few kilometres thick and comprises six sedimentary facies representing deposition from different kinds of sediment‐gravity flows. Representative lateral and vertical assemblages of one or more of these facies comprise six stratal elements, including: isolated scours, avulsion splays, feeder channels, distributary channels, terminal splays, and distal and off‐axis fine‐grained turbidite units. The internal characteristics of the various stratal elements do not differ from more distal to more proximal settings, but the relative abundance of the various stratal elements does. The difference in relative abundance of stratal elements in the kilometre‐scale stratigraphy of the Kaza Group results in a systematic upward change in architecture. The systematic arrangement of the stratal elements within the interpreted larger bodies, or lobes, and then lobes within the basin‐floor fan, suggests a hierarchical organization. In this article a hierarchy is proposed that is based on avulsion but, also importantly, the location of avulsion. The proposed avulsion‐based hierarchical scheme will be a useful tool to bridge the scalar gap between outcrop and seismic studies by providing a single stratigraphic framework and terminology for basin‐floor stratal elements.  相似文献