东营凹陷古近系成岩层序特征与储集差异性分析

根据对东营凹陷油气储层成岩规律的分析,结合层序地层单元的分布构架,发现成岩演化过程所决定的成岩相特征与层序地层分布有密切相关性。阐述了在层序界面附近和层序体内部成岩作用发生的一般规律,认识到油气储层的储集性受成岩相和成岩层序控制。认为东营凹陷古近系近期勘探所取得的一系列成果,与成岩作用的差异性有关。将储层储集特征和成岩层序特征有机结合,合理地解释了凹陷内油气富集规律。说明该区油气勘探工作必须有的放矢,科学布局,循序追踪,才能获得最佳勘探效果。     

赣东北鹅湖岭组的再认识

在分析赣东北鹅湖岭组及有关地层的地质特征、地层划分现状及产生分岐的原因的基础上,提出以岩性、岩相为划分依据,将鹅湖岭组与喷发相相对应,将其下界、上界分别置于沉积喷发相与喷发相、喷发相与喷发沉积相的相变界面上。从而将北京地质学院指定的打鼓顶组建组剖面上的"打鼓顶组"并入鹅湖岭组;将赣东北其它地区的鹅湖岭组下界由安山岩层顶界处上移至安山岩层之上灰绿色砂岩层的顶界处,将铅山一上饶一带鹅湖岭组上界下移至原鹅湖岭组上部的底界处。     

海州式磷矿床地质特征及其成矿模式

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。     

北黄海盆地东部坳陷中生界沉积特征及演化

北黄海盆地是我国近海勘探及研究程度均较低的中新生代叠合断陷盆地, 而东部坳陷是其内最具油气勘探前景的二级构造单元。通过岩芯观察与测井相分析, 结合三维地震资料, 认为东部坳陷中生界主要发育扇三角洲、辫状河三角洲、三角洲与湖泊沉积。受构造演化阶段的制约, 不同时期具有不同的沉积演化特征。其中中侏罗世处于湖盆的初期断陷期, 半深湖-深湖亚相发育, 仅在坳陷边缘见少量小规模的扇三角洲沉积。晚侏罗世处于断陷扩展期, 整体为一个完整的湖进-湖退旋回, 早期北部缓坡发育三角洲沉积, 南部及东部陡坡见扇三角洲沉积, 中后期则由于湖平面上升, 发育暗色泥岩为主的湖泊沉积, 晚期北部缓坡见小规模三角洲前缘沉积。早白垩世处于断陷萎缩期, 垂向发育2个正旋回沉积序列, 其中旋回下部以扇三角洲、辫状河三角洲相为主, 向上渐变为滨浅湖沉积。     

A sequence stratigraphic model for an intensely bioturbated shallow-marine sandstone: the Bridport Sand Formation, Wessex Basin, UK

The Bridport Sand Formation is an intensely bioturbated sandstone that represents part of a mixed siliciclastic‐carbonate shallow‐marine depositional system. At outcrop and in subsurface cores, conventional facies analysis was combined with ichnofabric analysis to identify facies successions bounded by a hierarchy of key stratigraphic surfaces. The geometry of these surfaces and the lateral relationships between the facies successions that they bound have been constrained locally using 3D seismic data. Facies analysis suggests that the Bridport Sand Formation represents progradation of a low‐energy, siliciclastic shoreface dominated by storm‐event beds reworked by bioturbation. The shoreface sandstones form the upper part of a thick (up to 200 m), steep (2–3°), mud‐dominated slope that extends into the underlying Down Cliff Clay. Clinoform surfaces representing the shoreface‐slope system are grouped into progradational sets. Each set contains clinoform surfaces arranged in a downstepping, offlapping manner that indicates forced‐regressive progradation, which was punctuated by flooding surfaces that are expressed in core and well‐log data. In proximal locations, progradational shoreface sandstones (corresponding to a clinoform set) are truncated by conglomerate lags containing clasts of bored, reworked shoreface sandstones, which are interpreted as marking sequence boundaries. In medial locations, progradational clinoform sets are overlain across an erosion surface by thin (<5 m) bioclastic limestones that record siliciclastic‐sediment starvation during transgression. Near the basin margins, these limestones are locally thick (>10 m) and overlie conglomerate lags at sequence boundaries. Sequence boundaries are thus interpreted as being amalgamated with overlying transgressive surfaces, to form composite erosion surfaces. In distal locations, oolitic ironstones that formed under conditions of extended physical reworking overlie composite sequence boundaries and transgressive surfaces. Over most of the Wessex Basin, clinoform sets (corresponding to high‐frequency sequences) are laterally offset, thus defining a low‐frequency sequence architecture characterized by high net siliciclastic sediment input and low net accommodation. Aggradational stacking of high‐frequency sequences occurs in fault‐bounded depocentres which had higher rates of localized tectonic subsidence.     

是地层单元还是构造单元？

古大陆边缘变质地质体性质的确定对于探讨大地构造演化具有十分重要的意义。由于后期变形变质作用的影响,原先不同的构造单元往往被改造成看似完整的一套地层单元,但在同位素年龄、变质程度、岩浆活动与地层的专属组合及其空间延伸等方面则变化很大,这在华北古陆北缘的单塔子群和南缘的太华群中最为典型。因此,笔者建议用“构造－岩相杂岩体带”填图法来取代以地层为骨架的变质岩区地质制图,这有助于确定该地区的大地构造演化进程。     

高陂区童子岩组沉积与聚煤特征

从野外第一手资料入手,分析了本区的童子岩组第三段中亚段的沉积特征。在此基础上,归纳出本区主采煤层沉积环境,并研究了主采煤层的聚煤特征。     

Transformation of garnet epidote amphibolite to eclogite, western Dabie Mountains, China

Omphacite and garnet coronas around amphibole occur in amphibolites in the Hong'an area, western Dabie Mountains, China. These amphibolites consist of an epidote–amphibolite facies assemblage of amphibole, garnet, albite, clinozoisite, paragonite, ilmenite and quartz, which is incompletely overprinted by an eclogite facies assemblage of garnet, omphacite and rutile. Coronas around amphibole can be divided into three types: an omphacite corona; a garnet–omphacite–rutile corona; and, a garnet–omphacite corona with less rutile. Chemographic analysis for local reaction domains in combination with petrographical observations show that reactions Amp + Ab + Pg = Omp +Czo + Qtz + H₂O, and Amp + Ab = Omp ± Czo + Qtz + H₂O may lead to the development of omphacite coronas. The garnet–omphacite–rutile corona was formed from the reaction Amp + Ab + Czo + Ilm ± Qtz = Omp + Grt + Rt + H₂O. In garnet–omphacite coronas, the garnet corona grew during an early stage of epidote amphibolite facies metamorphism, whereas omphacite probably formed by the reactions forming the omphacite corona during the eclogite facies stage. It is estimated that these reactions occurred at 0.8–1.4 GPa and 480–610 °C using the garnet–clinopyroxene thermometer and omphacite barometer in the presence of albite.     

中国东部苏鲁榴辉岩超基性岩褶皱带的演化及其与大别(中国)和柯切塔夫(哈萨克斯坦)杂岩的对比(英文)

苏鲁褶皱带形成于元古宙 (2 2 33～ 185 5Ma)典型优地槽构造环境 ,主要由石榴橄榄岩、石榴辉石岩、榴辉岩等侵入岩 (柯石英深度相地幔岩浆房中形成 )和它们的火山沉积建造围岩一起经褶皱、变质而形成。变质作用经历了先蓝片岩相 (前花岗岩 )后片麻岩混合岩相过程。由于变质作用的不规律性 ,苏鲁褶皱带可分为 2个构造带 :(1)东部构造带 (蓝片岩 )和 (2 )西部构造带 (片麻岩混合岩 )。根据A·都城秋穗所识别的变质带系统 ,可将其作为一个双变质带。东部构造带以出现许多块状、条带状榴辉岩辉石岩橄榄岩组合的残余岩块为特征 ,其中还残留着高压的矿物 (石榴石、绿辉石、柯石英 ) ,而且有被混合岩和各种交代岩替代的显著标志。在中生代 ,苏鲁元古褶皱带受造山作用的影响活化 ,导致许多花岗岩体的侵入 ,使交代岩广泛发育。