长江三角洲晚第四纪地层沉积特征与生物气成藏条件分析     

林春明  张霞  徐振宇  邓程文  殷勇  承秋泉 《地球科学进展》2015,30(5):589-601

对长江三角洲晚第四纪地层沉积特征进行了精细研究,探讨了研究区层序地层格架,在此基础上分析了浅层生物气成藏条件、特征和分布规律。研究表明,长江三角洲晚第四纪发育3期下切河谷,形成了3套沉积层序;因后期河流的强烈下切破坏,早期沉积层序往往被剥蚀殆尽,仅残留下部的河床相粗粒沉积,造成不同期河床相的叠置;相对而言,末次冰期以来形成的下切河谷沉积层序以相对完整的沉积相组合被保存下来。长江三角洲浅层天然气是未经运移的原生生物气,其主要富集于末次冰期以来的沉积层序内,气藏为自生自储同生型的岩性圈闭。河口湾—河漫滩和浅海相泥质沉积物既是气源岩,又是盖层,后者可作为良好的区域盖层;河口湾—河漫滩和河床相砂质沉积物为主要储集层。因此,研究区晚第四纪多期下切河谷沉积层序有利于浅层生物气藏的形成,特别是晚期下切河谷内河口湾—河漫滩相砂质透镜体以及河床相砂体可作为优先勘探目标。  相似文献   

鄂尔多斯盆地LFP区块长2段沉积相研究     

叶亚坤  苏海伦  薛永康  李阳阳 《地下水》2015,(4)

储层的沉积相研究通常是油气藏勘探开发过程中一项十分重要的任务,它控制着储集砂体的成因类型及宏观分布。在岩芯观察的基础上,结合综合录井资料和野外露头剖面信息,运用沉积学、沉积构造、剖面结构、古生物及测井相等划分沉积相的标志,对研究区内钻井进行单井沉积相划分,对不同钻井之间的沉积相进行综合比对,结果认为LEP区块长2段主要从三角洲前缘高建设的水下分流河道骨架砂体沉积为主。  相似文献   

Methodological comparison for quantitative analysis of fossil and recently derived carbon in mine soils with high content of aliphatic kerogen     

《Organic Geochemistry》2015

In mine soil, quantification of soil organic carbon (OC) derived recently from biomass decomposition is complicated by the presence of fossil (geogenic) C derived from coal, oil shale, or similar material in the overburden. The only reliable method for such measurement is ¹⁴C analysis (i.e. radiocarbon dating) using instrumentation such as accelerator mass spectrometry, which is too expensive for routine laboratory analysis. We tested two previously used and two new methods for recent C quantification and compared them with ¹⁴C AMS radiocarbon dating as a reference using a set of soil samples (n = 14) from Sokolov, Czech Republic: (i) ¹³C isotope ratio composition, (ii) cross polarization magic angle spinning ¹³C nuclear magnetic resonance (CPMAS ¹³C NMR) spectroscopy, (iii) near infrared spectroscopy (NIRS) coupled with partial least squares regression and (iv) Rock–Eval pyrolysis. Conventional methods for OC determination (dry combustion, wet dichromate oxidation, loss-on-ignition) were also compared to quantify any bias connected with their use. All the methods provided acceptable recent carbon estimates in the presence of mostly aliphatic fossil C from kerogen. However, the most accurate predictions were obtained with two approaches using Rock–Eval pyrolysis parameters as predictors, namely (i) S₂ curve components and (ii) oxygen index (OI). The S₂ curve approach is based on the lower thermal stability of recent vs. fossil organic matter. The OI approach corresponded well with ¹³C NMR spectra, which showed that samples rich in recent C were richer in carboxyl C and O-alkyl C. These two methods showed the greatest potential as routine methods for recent C quantification.  相似文献   

A Method for Determining Sedimentary Micro-Facies Belts Automatically     

Linfu Xue  Qitai Mei  Quan Sun 《世界地质(英文版)》2003,6(1)

It is important to understand the distribution of sedimentary facies, especially the distribution of sand body that is the key for oil production and exploration. The secondary oil recovery requires analyzing a great deal of data accumulated within decades of oil field development. At many cases sedimentary micro-facies maps need to be reconstructed and redrawn frequently, which is time-consuming and heavy. This paper presents an integrated approach for determining the distribution of sedimentary micro-facies, tracing the micro-facies boundary, and drawing the map of sedimentary micro-facies belts automatically by computer technique. The approach is based on the division and correlation of strata of multiple wells as well as analysis of sedimentary facies. The approach includes transform, gridding, interpolation, superposing, searching boundary and drawing the map of sedimentary facies belts, and employs the spatial interpolation method and "worm" interpolation method to determine the distribution of sedimentary micro-facies including sand ribbon and/or sand blanket. The computer software developed on the basis of the above principle provides a tool for quick visualization and understanding the distribution of sedimentary micro-facies and reservoir. Satisfied results have been achieveed by applying the technique to the Putaohua Oil Field in Songliao Basin, China.  相似文献   

南秦岭主要类型热水沉积岩的REE地球化学   总被引：1，自引：0，他引：1  

薛春纪  马国良  隗合明  曾章仁 《地球科学与环境学报》1996,(3)

南秦岭泥盆纪沉积柱中产有多种类型海底热水沉积岩．它们的ΣＲＥＥ偏低（平均６３．０９×１０－６），ＲＥＥ配分曲线平缓右倾，Ｌａ／Ｙｂ＝２～８，Ｃｅ亏损，总体上与海水相似。产于Ｓｅｄｅｘ含矿层中的热水沉积岩具有正Ｅｕ异常，与现代海底热液及红海热液沉积物可比；而产在Ｓｅｄｅｘ含矿层以下地层中的热水沉积岩Ｅｕ亏损，与ＥＰＲ热液沉积物相似。ＲＥＥ地球化学研究和岩石学研究结果一致，支持热水沉积岩ＲＥＥ来源于海水及部分下伏沉积柱（包括基底），含矿热水沉积岩是盆地热演化到一定阶段具有一定深度和规模的循环对流体系在海底的化学沉积，而Ｓｅｄｅｘ含矿层以下地层中的热水沉积岩则是浅部热水对流循环的海底显示．成岩和变质作用对岩石的ＲＥＥ未造成影响。  相似文献   

河南卢氏—西峡地区小寨组的沉积相     

叶俭  李荣西 《地球科学与环境学报》1993,(4)

石界河群小寨组主要为砂、泥质碎屑沉积,按岩性可分为四个组合,下部黑云母石英片岩与变质杂砂岩组合及变质副砾岩与变质杂砂岩组合为浊流及碎屑流沉积,上部的变质砾岩与变质含砾砂岩组合及变质杂砂岩、千枚岩组合为扇三角洲沉积。综合上述沉积相组合,提出小寨组并非大洋或深海盆地,而应为靠近陆源地的断陷盆地中的碎屑沉积。  相似文献   

Organic carbon and nitrogen stable isotopes in the intertidal sediments from the Yangtze Estuary, China   总被引：2，自引：0，他引：2  

Liu M  Hou LJ  Xu SY  Ou DN  Yang Y  Yu J  Wang Q 《Marine pollution bulletin》2006,52(12):1625-1633

The natural isotopic compositions and C/N elemental ratios of sedimentary organic matter were determined in the intertidal flat of the Yangtze Estuary. The results showed that the ratios of carbon and nitrogen stable isotopes were respectively −29.8‰ to − 26.0‰ and 1.6‰–5.5‰ in the flood season (July), while they were −27.3‰ to − 25.6‰ and 1.7‰–7.8‰ in the dry season (February), respectively. The δ¹³C signatures were remarkably higher in July than in February, and gradually increased from the freshwater areas to the brackish areas. In contrast, there were relatively complex seasonal and spatial changes in stable nitrogen isotopes. It was also reflected that δ¹⁵N and C/N compositions had been obviously modified by organic matter diagenesis and biological processing, and could not be used to trace the sources of organic matter at the study area. In addition, it was considered that the mixing inputs of terrigenous and marine materials generally dominated sedimentary organic matter in the intertidal flat. The contribution of terrigenous inputs to sedimentary organic matter was roughly estimated according to the mixing balance model of stable carbon isotopes.  相似文献   

Late Pleistocene sea-level oscillations (MIS 10–2) recorded in shallow marine and coastal plain sediments of the southern Wanganui Basin, New Zealand     

Glenn R. Hughes  David M. Kennedy   《Quaternary Research》2009,71(3):477-489

The northern Wanganui Basin, New Zealand, is one of the key global sites for understanding marine cyclic sedimentation during the Quaternary. This paper presents the first evidence of marine cyclic sedimentation from its central-southern parts. Sedimentological, micropalaeontological and palynological analyses on a 280-m-deep borehole encountered units dating back to MIS 10. The sequence includes four marine cycles spanning MIS 9–5, which are overlain by terrestrial fluvial aggradation surfaces dating from MIS 4–2. Each marine unit represents a progressively shallowing depositional environment from the mid-shelf to coastal plain. This is overlain by a terrestrial sequence of lowstand fluvial terraces. Localized fault movements appear to have influenced the sedimentary character of the sequence during MIS 7a and 5e producing basement highs which provided protection to the shoreline. The cyclothems described in this paper now extend the already extensive, previously described record from MIS 17–10 to produce a combined eustatic record of Quaternary sea level change within the basin to MIS 5. They also provide an excellent example of the sedimentary response of a coastal basin to a progressive loss of sedimentation accommodation space.  相似文献   

Stratigraphy, depositional environments and level reconstruction of the last interglacial Lake Samra in the Dead Sea basin   总被引：1，自引：0，他引：1  

N. Waldmann  M. Stein  A. Starinsky 《Quaternary Research》2009,72(1):1-185

In this paper we describe the stratigraphy and sediments deposited in Lake Samra that occupied the Dead Sea basin between ∼ 135 and 75 ka. This information is combined with U/Th dating of primary aragonites in order to estimate a relative lake-level curve that serves as a regional paleohydrological monitor. The lake stood at an elevation of ∼ 340 m below mean sea level (MSL) during most of the last interglacial. This level is relatively higher than the average Holocene Dead Sea (∼ 400 ± 30 m below MSL). At ∼ 120 and ∼ 85 ka, Lake Samra rose to ∼ 320 m below MSL while it dropped to levels lower than ∼ 380 m below MSL at ∼ 135 and ∼ 75 ka, reflecting arid conditions in the drainage area. Lowstands are correlated with warm intervals in the Northern Hemisphere, while minor lake rises are probably related to cold episodes during MIS 5b and MIS 5d. Similar climate relationships are documented for the last glacial highstand Lake Lisan and the lowstand Holocene Dead Sea. Yet, the dominance of detrital calcites and precipitation of travertines in the Dead Sea basin during the last interglacial interval suggest intense pluvial conditions and possible contribution of southern sources of wetness to the region.  相似文献   

青藏高原大型走滑断裂带晚新生代构造地貌生长及水系响应   总被引：5，自引：0，他引：5       下载免费PDF全文

付碧宏  时丕龙  贾营营 《地质科学》2009,44(4):1342-1363

大型走滑断裂带对调节印度板块和亚洲板块碰撞后产生的陆内构造变形和地貌生长起着非常重要作用。本文分析了沿青藏高原北缘主要大型左旋走滑断裂带：东昆仑、康西瓦和鲜水河-小江断裂带发育的错断地质体、大型错断水系或水系拐弯等新构造地貌特征,表明这些大型走滑断裂带在晚新生代以来发生了大规模的左旋走滑运动：前新生代地质体错位距离为80～120 km,大型水系累积的位移量可达80～90 km。根据这些走滑断裂带的长期走滑速率为8～12 mm/a,估算上述大型走滑断裂带的左旋走滑运动开始于中新世晚期：东昆仑和康西瓦断裂带左旋走滑运动开始于10±2 Ma; 鲜水河-小江断裂带甘孜-玉树段的左旋走滑运动的开始时间约为8～115 Ma。同样,如果大型水系的沿断裂带出现的大型错位或拐弯能够代表断裂带累积错位的上限,表明发源于青藏高原的黄河、金沙江、喀拉喀什河和玉龙喀什河等一级水系上游大致开始形成于9～7 Ma±。西昆仑山前盆地中河流相沉积的最早响应时间为8～6 Ma,与喀拉喀什河和玉龙喀什河等西昆仑山地区一级水系的形成时间基本一致,表明这些大型水系初始形成时间与左旋走滑构造运动的开始时间准同时。这表明中新世中晚期青藏高原构造演化发生了重要转变。  相似文献