宜昌砾石层的沉积环境及地貌意义   总被引：5，自引：0，他引：5       下载免费PDF全文

李庭 李长安  康春国  雷文大杨 建王节涛 《中国地质》2010,37(2):438-445

宜昌砾石层上覆中更新世网纹红土,下伏白垩纪红层,共有22个岩性层组成,总厚超过100m。通过对宜昌地区剖面出露砾石层的沉积相分析表明,善溪窑和云池剖面由下至上出现冲积扇扇中-扇根亚相;李家院剖面与上述两剖面间有沉积间断,由下至上出现冲积扇扇端-扇中亚相。粒度分析也证明了该砾石层中的砂体属冲积扇中的辫状水道沉积,与沉积相分析所得结论一致。研究认为,宜昌砾石层具有典型的冲积扇沉积环境特征,主要为冲积扇扇顶部分。该冲积扇在宜昌东南地区如此大规模的发育,显示其形成时具有强大的水动力条件,通过对其形成的地貌环境意义进行探讨,初步认为,该冲积扇为长江三峡贯通的产物。据前人研究推断,宜昌砾石层的形成时代应该在1.08～0.73MaB.P.,三峡贯通应在1.0MaB.P.之前。  相似文献   

珠江口盆地荔湾井区珠江组深水扇沉积特征   总被引：4，自引：1，他引：3       下载免费PDF全文

王昌勇郑荣才  高博禹朱国金  胡晓庆李 云 《中国地质》2010,37(6):1628-1637

珠江口盆地白云凹陷荔湾深水区为油气勘探有利区域,通过岩石学和古生物组合特征研究,认为该区珠江组下部属于典型的深水扇沉积,可划分为早期盆地扇和晚期斜坡扇两种类型,两类深水扇都以发育颗粒流、砂质碎屑流及低密度浊流等顺坡重力流沉积为主,同时夹有少量内波和等深流等深水牵引流改造沉积。砂质碎屑流为两类深水扇水道砂体的主要沉积类型,发育有逆-正粒序层理、平行层理和水平层理,粒序层内可见各种丰富的液化变形和生物逃逸构造,而水平层内发育有更多的生物钻孔和扰动现象。两类深水扇的沉积构造和古生物特征有明显差异,其中盆地扇水道砂岩中普遍含硅质小砾石,水道间泥岩中含有较多保存完好的抱球虫化石,斜坡扇水道砂岩以富含炭泥屑为典型特征,水道间泥岩含有更丰富的颗石藻和抱球虫化石,其中部分抱球虫和颗石具有遭受海底溶蚀作用的现象,指示斜坡扇相对盆地扇有更大的水体深度。平面上两类深水扇具有相似的重力流沉积的分带性,都具有自陆架坡折向盆地方向由颗粒流沉积逐渐向砂质碎屑流和近源高密度浊流、远源低密度浊流等单向演化的特点。  相似文献   

苏北盆地高邮凹陷深凹带东部古近系戴南组二段沉积相及沉积演化          下载免费PDF全文

姚玉来  林春明  高丽坤  刘玉瑞  马英俊  李艳丽  张霞  张志萍 《沉积与特提斯地质》2010,30(2):1-10

通过岩心观察描述和测井、录井、分析化验资料等综合分析,结合区域地质背景,对高邮凹陷深凹带东部古近系戴南组二段的沉积相类型及其分布、演化特征进行了系统研究。结果表明,戴二段发育扇三角洲、三角洲和湖泊三种沉积相类型,扇三角洲分布在南部陡坡区,三角洲分布在北部缓坡区,湖泊分布在扇三角洲、三角洲侧翼及深凹带中央地带,这种沉积格局受凹陷周边断层和古地形控制。平面上从凹陷边缘至中心,沉积相由扇三角洲相或三角洲相渐变为滨浅湖相;垂向上自下而上,沉积物粒度呈现粗-细-粗的变化规律。戴二段沉积演化可划分为初、早、中、晚和末期五个阶段。各时期的沉积特征、沉积相展布表现各异,总体表现出水体由浅变深,再次变浅,扇三角洲和三角洲先退积后进积的特点。末期湖盆整体抬升,戴二段地层顶部遭受剥蚀,与上覆地层呈不整合接触。  相似文献   

陡坡复杂扇体油藏评价思路与方法     

徐兵  刘惠民  周爱华 《上海国土资源》2010,31(Z1)

本文以东营凹陷北部陡坡带为例论述了陆相断陷盆地陡坡复杂扇体油藏评价思路与方法。分析了陡坡带特殊性及复杂性,针对复杂扇体油藏精细等时地层对比、控砂机制、有效储层划分和油气分布的纵向分带性提出了有效的研究方法,并形成了一整套有针对性的勘探技术流程,在东营凹陷乃至济阳坳陷具有较好的推广前景。  相似文献   

黔东南与黔西南浊积岩中两种不同类型金矿的比较     

王甘露  赵万飞  苏杭  卞华鹏  张峰玮  李青枫 《世界地质(英文版)》2014,(3)

黔西南和黔东南是贵州的两个主要产金地区,大部分金矿都产于浊积岩中。但黔西南的金矿主要是含金蚀变岩型（或称卡林型、微细浸染型）,以不可见金为主;黔东南的金矿却是含金石英脉型,以明金为主。这两种金矿都产在造山带,赋矿围岩是浊积岩,区内岩浆侵入作用不显著,成矿受背斜与断裂控制,成矿温度不高,矿石物质成分基本一致。研究表明,产生不同类型矿化的原因主要在于：黔东南地区的容矿岩石是浅变质的硅质碎屑岩,碳酸盐矿物很少;而黔西南地区是未变质的富钙硅质碎屑岩,碳酸盐矿物多。前者形成石英脉型金矿床,后者形成蚀变岩型金矿床。  相似文献   

南海琼东南盆地深水区储层类型及研究意义   总被引：1，自引：1，他引：0       下载免费PDF全文

王艳 《沉积与特提斯地质》2014,34(3):82-87

通过对琼东南盆地钻井及典型地震相分析,认为琼东南盆地深水区发育两种类型的储层:第一类为形成于浅水环境的储层,包括扇三角洲砂体、滨浅海相滩坝砂体和台地碳酸盐岩;第二类为形成于深水环境的储层,包括盆底扇和峡谷水道等低位砂体。其中,深水区广泛分布的海底扇、峡谷水道砂体和台地碳酸盐岩具有良好的深水油气勘探潜力。  相似文献   

Matrix‐rich and associated matrix‐poor sandstones: Avulsion splays in slope and basin‐floor strata     

Viktor Terlaky  Robert William Charles Arnott 《Sedimentology》2014,61(5):1175-1197

A common facies observed in deep‐water slope and especially basin‐floor rocks of the Neoproterozoic Windermere Supergroup (British Columbia, Canada) is structureless, coarse‐tail graded, medium‐grained to coarse‐grained sandstone with from 30% to >50% mud matrix content (i.e. matrix‐rich). Bed contacts are commonly sharp, flat and loaded. Matrix‐rich sandstone beds typically form laterally continuous units that are up to several metres thick and several tens to hundreds of metres wide, and commonly adjacent to units of comparatively matrix‐poor, scour‐based sandstone beds with large tabular mudstone and sandstone clasts. Matrix‐rich units are common in proximal basin‐floor (Upper Kaza Group) deposits, but occur also in more distal basin‐floor (Middle Kaza Group) and slope (Isaac Formation) deposits. Regardless of stratigraphic setting, matrix‐rich units typically are directly and abruptly overlain by architectural elements comprising matrix‐poor coarse sandstone (i.e. channels and splays). Despite a number of similarities with previously described matrix‐rich beds in the literature, for example slurry beds, linked debrites and co‐genetic turbidites, a number of important differences exist, including the stratal make‐up of individual beds (for example, the lack of a clean sandstone turbidite base) and their stratigraphic occurrence (present throughout base of slope and basin‐floor strata, but most common in proximal lobe deposits) and accordingly suggest a different mode of emplacement. The matrix‐rich, poorly sorted nature of the beds and the abundance and size of tabular clasts in laterally equivalent sandstones imply intense upstream scouring, most probably related to significant erosion by an energetic plane‐wall jet or within a submerged hydraulic jump. Rapid energy loss coupled with rapid charging of the flow with fine‐grained sediment probably changed the rheology of the flow and promoted deposition along the margins of the jet. Moreover, these distinctive matrix‐rich strata are interpreted to represent the energetic initiation of the local sedimentary system, most probably caused by a local upflow avulsion.  相似文献   

湘东南—赣西地区加里东期沉积演化特征     

李聪  陈世悦  张鹏飞  冯建松  王倩  李旭  史英  左虎 《地质论评》2014,60(5):1167-1174

通过对研究区加里东期沉积物的野外地质调查、剖面横向对比和岩相古地理编图,发现研究区加里东期主要发育五种沉积相类型,分别为碳酸盐岩陆棚相、碎屑岩—碳酸盐岩混积陆棚相、冰海相、欠补偿型硅质岩—页岩盆地相和补偿型浊积岩盆地相。剖面横向对比显示,研究区加里东期沉积物由西向东为连续相变沉积,横向上各种沉积相指状交叉、相互过渡;岩相古地理研究表明,加里东期湘东南—赣西地区主要发育硅质岩—页岩盆地相和浊积岩盆地相两大相带,从南华纪—奥陶纪时期两大相带的发育规模略有差异,在两大相带的结合部往往发育两种沉积相的交叉过渡带。笔者认为该区沉积相的过渡性质对探讨华南洋加里东期属性的问题有重要意义。  相似文献   

柴北缘牦牛山地区牦牛山组沉积相组合特征   总被引：5，自引：0，他引：5  

夏文静  牛漫兰  闫臻  吴齐  郭现轻  付长垒  李继亮 《地质学报》2014,88(5):943-955

柴达木盆地北缘牦牛山地区出露的牦牛山组是一套由冲积扇和扇三角洲相共同构成的陆相沉积组合,冲积扇相砾岩-粗砂岩组合主要分布于研究区SE侧,扇三角洲相砂岩-泥岩组合主要分布于研究区NW侧。古水流分析表明牦牛山组沉积物主要来自其SE侧古隆起,但后期扇三角洲相包含少量来自NW和NE向的沉积物。该套沉积组合序列特征与区域上分布在牦牛山西侧同时期形成的湖泊相、滨浅海相沉积共同表明,柴达木盆地北缘在晚志留-早泥盆世时期存在一NW向倾斜的古斜坡,且晚期北侧发生抬升。砾岩和砂岩碎屑组成与区域岩石组合类型对比表明,牦牛山组沉积碎屑物主要来自于滩间山群。沉积组合序列特征、碎屑组成和区域构造背景综合研究表明,牦牛山组可能为柴达木板块向北俯冲过程中形成的局部断陷盆地的充填物。  相似文献   

The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: stable isotopic evidence from ODP Site 1167     

Kevin M. Theissen  Robert B. Dunbar  Alan K. Cooper  David A. Mucciarone  Dirk Hoffmann 《Global and Planetary Change》2003,39(3-4):227-256

Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based δ¹⁸O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36.9±3.3 ka at 0.45 m below sea floor and correlate suspected glacial–interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The δ¹⁸O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early–mid-Pleistocene (0.9–1.38 Ma). An increase in δ¹⁸O values after 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The δ¹⁸O record in the upper 50 m of the stratigraphic section indicates as few as three glacial–interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16–21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic stratigraphy. Our results suggest the potential for the recovery of useful stable isotopic records in other TMFs.  相似文献