塔中北坡中-下奥陶统碳酸盐岩缝洞方解石充填物地球化学特征差异及其对储层的指示意义

方解石胶结充填孔洞及裂缝是破坏塔中北坡中-下奥陶统碳酸盐岩储层储集空间最主要的成岩作用,工区单井取心段发育的孔洞和裂缝中存在大量的方解石充填物。通过对中石化塔中北坡矿权区8口单井的孔洞及裂缝方解石充填物取样,基于镜下薄片、阴极发光、碳氧同位素、包裹体以及稀土元素等特征的综合分析表明,一间房组孔洞方解石充填物在保留原始海源流体信息的同时遭受了大气淡水的影响,指示一间房组存在较为典型的(准)同生期大气水溶蚀作用,形成了早期溶蚀孔洞,储集空间为早期充填残余孔;鹰山组裂缝方解石充填物基本不具有同期海相方解石的特征,地球化学特征显示其属于热液成因,反映鹰山组储集空间分布受构造热流体控制,且在彼此相邻、性质相似的2条走滑断裂带内部,构造热流体具有同源性。     

黄骅坳陷三马地区中-深部储层成岩作用及主控因素分析

黄骅坳陷三马地区储集岩样品的显微特征及成岩矿物的组合关系分析结果表明，三马地区下第三系中深层储层主要处于晚成岩A期，成岩现象包括石英、长石的次生加大、碳酸盐矿物胶结作用、矿物交代作用、溶解作用和粘土矿物转化作用等。其中石英次生加大于2700m左右开始出现，随埋深增大，石英增生加强；长石次生加大现象不十分普遍；碳酸盐胶结作用包括早期自生泥晶方解石胶结作用、连晶方解石和晚期白云石(或铁方解石)的胶结作用。在扫描电镜下可见到方解石与含铁方解石集合体充填在粒间孔隙中或与石英、钠长石及粘土矿物共生，白云岩多呈菱形粒状分布于粒间；常见的交代现象主要有方解石交代长石、石英及粘土矿物，粘土矿物交代长石、石英等；溶解作用主要有长石的溶解、碳酸盐颗粒的溶解和方解石胶结物的溶解等，粘土矿物的转化主要为蒙脱石、高岭石向伊利石(或绿泥石)转化。还讨论了储层岩相、岩性特征、孔隙水中有机酸含量、早期方解石的充填、烃类早期注入等因素对储层成岩演化的控制作用。     

塔里木盆地北部下奥陶统碳酸盐岩孔洞充填物特征及其成岩环境分析

为了正确分析和评价碳酸盐岩溶蚀孔洞在埋藏成岩环境中的发育和保存条件,对塔里木盆地北部露头剖面中下奥陶统白云岩及其溶蚀孔洞的充填物进行了详细的矿物学和地球化学研究,试图对这类孔洞充填物沉淀时的成岩环境进行恢复。大型洞穴充填物的矿物学特征和微孔洞充填物扫描电镜的分析表明,此类孔洞的环带状充填物具有明显的世代性,由基岩向孔洞中心,至少可识别出4期充填物,即第1期的乳白色白云石,第2期的铁质浸染的杂色高镁方解石,第3期的无色透明白云石和第4期的自形石英。碳、氧同位素分析结果表明,孔洞充填物形成于高温条件,结合微量元素、稀土元素所示的成岩信息可进一步推断其形成于高温埋藏环境,而非现代表生暴露期的充填物;第1期和第3期白云石充填物形成在相对还原且高盐度的流体性质条件下,而第2期高镁方解石充填物沉淀时相对偏氧化,盐度也偏低。据下奥陶统此类4期充填物的特征分析可知,第2期高镁方解石充填物的发育可能与构造抬升导致成岩环境的改变有关。     

鄂尔多斯盆地中东部奥陶系储层控制因素分析

鄂尔多斯盆地中东部奥陶系呈现出宽缓的盆缘含硬石膏白云岩坪与盆缘硬石膏白云岩坪相带，为孔洞型储层的成层发育、大面积展布创造了良好的条件。中部地区储层物性明显好于东部地区。本文从古岩溶地貌、古沟槽展布、压释水分布以及孔洞充填物类型的差异，系统分析了储层分布的控制因素。进而利用电子探针分析、同位素分析及包裹体测温，探讨了孔隙充填物的类型及形成环境。充填物中的白云石主要包括微成水微晶白云石、淡水白云石及马鞍状白云石三种类型，方解石主要包括微咸水粉细晶方解石、淡水方解石及铁方解石三种类型。微咸水微晶白云石和微成水粉细晶方解石主要形成于同生期层间岩溶发育期，淡水白云石及淡水方解石主要形成于裸露期风化壳岩溶发育期，马鞍状白云石及铁方解石主要形成于中深埋藏环境。     

鄂尔多斯盆地古隆起东北侧马五_4~1储层膏模孔类型及充填过程分析

利用岩芯和薄片资料,通过薄片孔隙描述、铸体薄片图像分析等方法,在对研究区马五14储层孔隙类型划分的基础上,详细划分了膏模孔充填类型,并对其充填过程进行了阐述。研究结果表明,研究区马五14储层主要发育溶蚀孔(膏模孔和其他溶孔)、晶间孔、晶间溶孔、微裂缝4种类型的孔隙,且以膏模孔为主。通过镜下薄片对膏模孔内不同充填物观察发现,充填物主要为白云石、方解石、硬石膏,其中半充填的膏模孔中主要充填物为白云岩粉砂、白云岩粉砂+石英、白云岩粉砂+铁白云石3种类型,而全充填的膏模孔中主要充填物为白云岩粉砂+方解石、白云岩粉砂+石英+方解石、白云岩粉砂+硬石膏3种类型。综合分析认为膏模孔是含膏云岩中石膏等易溶晶体溶蚀后,晶体轮廓保留而形成的,首先裸露风化壳期先充填白云岩粉砂和深灰色方解石,其次深埋藏期充填自生石英、白色亮晶方解石、铁白云石及硬石膏。     

方解石充填物对于深层古岩溶洞穴保存的独特意义--以塔河地区奥陶系为例

塔河油田奥陶系古岩溶洞穴埋藏深度之大在世界范围内罕见,但对其为何没有垮塌殆尽的原因却知之甚少。为了探究其保存机制,对比了Fort Worth盆地奥陶系深埋洞穴,发现大量缝、洞充填方解石是塔河地区洞穴中常见且特有的充填物。在统计和综合分析缝洞方解石充填物地球化学数据的基础上,以洞穴充填方解石成因类型为切入点,详细分析了构造运动背景、热液活动、油气充注、方解石的产状以及洞穴受力情况,通过与Fort Worth盆地深埋洞穴埋藏史的对比和分析,提出塔河地区深埋岩溶洞穴的一种保存机制。研究区岩溶洞穴方解石主要是长期浅埋阶段,以大气淡水成因为主,海水成因为辅形成,深埋过程还受到了溶蚀性流体（岩浆热液和有机酸）后期改造。方解石充填物增加了洞穴的抗压性,岩溶洞穴内部充填的方解石在埋藏过程中支撑了洞穴;岩溶洞穴顶部裂纹中充填的方解石还“愈合”了洞穴周边的裂纹,强化了洞穴的顶板,增加了洞穴整体的稳定性。充填的方解石在垮塌前占据了部分洞穴空间,在埋藏后,高温有机酸、CO₂、H₂S和岩浆热液沿着深大断裂等通道对奥陶系碳酸盐岩改造溶蚀作用明显,也对处于优势通道和良好储集性能的洞穴充填方解石进行了改造,恢复了部分洞穴空间。因而认为地表、近地表方解石充填过程是碳酸盐岩洞穴型储层的“保持性成岩作用”。     

塔河油田溶洞充填物的元素地球化学特征及环境意义

塔河油田位于塔里木盆地塔北隆起阿克库勒凸起的西南部,加里东-海西期强烈抬升导致的大气淡水岩溶作用、早石炭世发生的广泛海侵以及二叠纪大规模的火山活动,对奥陶系岩溶储层产生了不同程度的改造。对塔河地区的地质演化特征以及塔河油田地区溶洞砂泥质充填物镓、铷、锶、钡等微量元素和稀土元素的研究表明,大部分样品表现出淡水岩溶特征,仅T615井等4口井的溶洞充填物却表现出海水成因特征,充填物的元素地球化学特征表现出与早期大气淡水岩溶作用的叠加效应;此外,还有少量样品具有能反映热液作用特征的Eu正异常,说明该区碳酸盐岩地层也受热水溶蚀作用的影响。通过溶洞方解石和溶洞方解石胶结物碳、氧同位素值分布特征的分析也证实了塔河地区除了发育大气淡水岩溶作用外,还存在海水-淡水混合水溶蚀作用和热液溶蚀作用。     

鄂尔多斯盆地古隆起东北侧马五41储层膏模孔类型及充填过程分析

利用岩芯和薄片资料,通过薄片孔隙描述、铸体薄片图像分析等方法,在对研究区马五₄1储层孔隙类型划分的基础上,详细划分了膏模孔充填类型,并对其充填过程进行了阐述。研究结果表明,研究区马五₄1储层主要发育溶蚀孔（膏模孔和其他溶孔）、晶间孔、晶间溶孔、微裂缝4种类型的孔隙,且以膏模孔为主。通过镜下薄片对膏模孔内不同充填物观察发现,充填物主要为白云石、方解石、硬石膏,其中半充填的膏模孔中主要充填物为白云岩粉砂、白云岩粉砂+石英、白云岩粉砂+铁白云石3种类型,而全充填的膏模孔中主要充填物为白云岩粉砂+方解石、白云岩粉砂+石英+方解石、白云岩粉砂+硬石膏3种类型。综合分析认为膏模孔是含膏云岩中石膏等易溶晶体溶蚀后,晶体轮廓保留而形成的,首先裸露风化壳期先充填白云岩粉砂和深灰色方解石,其次深埋藏期充填自生石英、白色亮晶方解石、铁白云石及硬石膏。     

塔里木盆地轮南地区下奥陶统碳酸盐岩岩溶储层特征及形成模式

轮南地区是塔里木盆地重点产油气地区之一,对其下奥陶统碳酸盐岩储层性能及分布的研究具有重要的实际意义。通过对研究区岩溶、裂缝发育、沉积和洞穴充填物分析研究,认为具渗透可溶性碳酸盐岩及温暖潮湿、多大气降水是岩溶储层形成的必要条件,构造裂缝的发育为岩溶储层发育创造了有利条件。根据裂缝性质及充填程度,本区裂缝可分为方解石完全充填张裂缝、方解石半充填张裂缝、泥质充填扭压性裂缝、未充填微细裂缝和缝合线5种,其中方解石半充填裂缝和缝合线对储层岩溶发育起重要作用。本区岩溶具明显的垂直分带性,可分为垂直渗流岩溶带、水平潜流岩溶带和过渡带,其中垂直渗流带底部及水平潜流岩溶带上部储集物性最佳。轮南地区发育的两期岩溶与石炭纪两次较大的海侵时间相一致。作者还研究了充填物的沉积特征,探讨了储层的演化模式。     

准噶尔盆地西北缘石炭—二叠系火山岩裂缝中方解石脉成因

准噶尔盆地西北缘石炭—二叠系火山岩裂缝十分发育, 普遍充填方解石矿物。通过对钻井岩心裂缝类型划分、 方解石脉原生流体包裹体均一温度测试、 方解石地球化学数据测试与分析, 揭示了方解石脉成因。结果表明, 石炭—二叠系火山岩中的裂缝主要包括风化裂缝、 构造裂缝、 成岩裂缝和溶蚀裂缝。裂缝中方解石的原生流体包裹体均一温度分布为40℃～150℃, 变化范围较大, 具有低温、 高温及混合流体特征。方解石的碳、 氧同位素表明, 方解石的形成与大气淡水和埋藏流体有关, 锶同位素和锰元素进一步证实, 埋藏流体为深部热液流体或埋藏流体溶蚀了火山物质。准噶尔盆地西北缘石炭—二叠系火山岩受逆冲推覆构造和风化淋滤作用双重影响, 构造裂缝和风化裂缝彼此连通并沟通了深部热液与大气淡水。在火山岩裂缝中形成了兼具大气淡水与深部热液流体特征的方解石充填物。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861