温湿气候区结晶岩与碎屑岩腐岩特征及其发育过程

发育于斜坡非饱和带的结晶岩与碎屑岩腐岩多夹于残坡积土层和风化岩带之间,保留有裂隙及层理等构造,但质地松软。腐岩结构体与母岩色差显著,保留原岩结构和构造特征,矿物成分以次生粘土矿物、次生石英及褐铁矿最为常见。腐岩次生微孔隙发育,具有低密度、高孔隙度、高渗透率、高容水度及高持水度特征。腐岩发育是通过低渗透岩石结构体风化前锋的渐进性扩展实现的,非饱和带高湿度空气形成的凝结水和降水入渗形成的非饱和渗流是该过程的核心动力。气态水分子能够扩散到低渗透岩石结构体表面内侧一定宽度范围内的孔隙系统之中凝结为液态水并溶蚀造岩矿物。雨季入渗降水在结构体表面形成的薄膜水流通过分子扩散机制接受其内侧结构体粒间溶液中的溶出组分并将其携入饱水带,同时恢复粒间溶液的侵蚀动力。当上述过程循环到一定程度时,结构面内侧便形成一定厚度的腐岩壳。腐岩壳在雨季直接吸收、贮存流经其表面的液态渗入水,在核心石外侧形成富水结构层并在旱季向包气带或其内侧的风化前锋提供水汽。随着时间推移,腐岩壳越来越厚,核心石最终消失;当某一范围内的岩石结构体全部演变为腐岩结构体时,该范围内的岩体也就完成了向腐岩体的转变。     

斜坡非饱和带低渗透岩石结构体风化前锋扩展过程

非饱和带低渗透岩石结构体风化前锋扩展是斜坡灾害孕育过程中的关键环节之一。到目前为止,化学风化领域的研究成果主要集中在高水-岩比的饱和环境下单矿物及矿物成分单一的碳酸盐岩的风化动力学方面,非饱和环境下的岩石风化研究还主要限于风化产物的特性描述方面。斜坡非饱和带低渗透岩石结构体风化前锋扩展是一种高度复杂的THMC过程。由于在溶解对象、溶解液及溶解过程的水动力-水化学环境等方面存在的显著差异,既有的地质材料风化动力学成果为探索这一复杂过程提供了理论储备,但还不能阐明其核心机理。斜坡非饱和带低渗透岩石结构体风化前锋的扩展过程研究不仅可以加深人们对斜坡灾害孕育的理解,为灾害预报-预警及其控制提供理论依据,同时可以促进岩石-岩体力学及浅表生水文地球化学等相关学科的交叉与发展。     

硅酸盐岩斜坡水岩化学作用

综合采用现场调查、结构体物理-水理参数的高精度测试及室内试验等研究方法,对硅酸盐岩斜坡的水岩化学作用问题进行了探讨。结果表明,新鲜硅酸盐岩结构体结构致密、孔隙度低、孔隙细小,多属不透水介质。硅酸盐岩斜坡区的水岩化学作用主要发生于非饱和带和水位变动带,地下水多年最低水位以下的饱和带所占份额很小。饱和带内的水岩化学作用只能发生于结构体表面,是一种结构面开度逐渐增大、结构体逐渐变小的缓慢溶解过程。非饱和带及水位变动带水岩化学作用初期的溶解液主要是水气转化的凝结水,所形成的腐岩保留原岩结构、构造和体积,是一种等容转换过程。旱季时,气态水分子扩散到硅酸盐岩结构体表面内侧一定宽度范围内的微孔隙系统之中凝结为液态水并溶蚀造岩矿物;雨季时,入渗降水在结构体表面形成的薄膜水流接受结构体粒间溶液中的溶出组分并将其携入饱水带。当上述过程循环到一定程度时,结构体就会转变为腐岩结构体。覆盖有一定厚度的残坡积土层和植被盖层的硅酸盐岩斜坡有利于水岩化学作用的发生。     

两种典型碳酸盐岩红土风化剖面的物理化学特征

通过对贵州遵义和平坝两种典型碳酸盐岩风化剖面的系统采样,在室内进行了岩土工程上常用的13项物理指标的测试和12项常量化学元素的全分析,在此基础上论述了它们在风化剖面上的分布及变化特征。指出土层孔隙率(孔隙比)由表层土到深处由高到低的变化,导致岩(土)层透水率逐渐降低和含水量的增加,是土层物理性质及相关力学性质变化的主因; 表层土以粘土粒组为主,到靠近基岩附近变为以粉土粒组为主,说明后期红土化作用可使土粒变细; 靠近岩石界面土层的粒径与组成石灰岩和白云岩矿物颗粒大小相当,这可能是地下水溶蚀- 交代矿物颗粒继承发育的结果; 通过分析界面各层(基岩- 溶滤层- 杂色粘土层)化学成分的变化可以看出,由岩石到土层可溶性组分( CaO、MgO)大量的被水溶蚀带走,成土元素( SiO2、Al2O3、Fe2O3 等)呈突跃式增加,而且两类岩石溶蚀成土的初期阶段(由岩石到溶滤层)可溶元素被溶蚀及成土元素的积累有很大的差别。      

东秦岭陕西聂家沟剖面二叠纪—三叠纪之交沉积特征及其古环境意义*

东秦岭陕西镇安聂家沟地区二叠纪—三叠纪之交发育一套海相碳酸盐岩沉积序列,较完整地记录了二叠纪末生物大灭绝事件前后浅海碳酸盐岩台地相生物群落演替及环境变化等信息,是研究二叠纪末生物大灭绝事件前后生态环境变化与沉积响应的理想区域。通过碳酸盐岩微相分析方法,对陕西镇安聂家沟剖面二叠系—三叠系界线附近的碳酸盐岩生物组合和微相类型进行了详细分析,共识别出11个微相类型: 斑点状凝块石、叠层石灰岩、鲕粒—纹层状叠层石灰岩、有孔虫颗粒灰岩、藻—海百合泥粒灰岩、含有被包壳和被磨蚀骨屑颗粒的粒泥灰岩、鲕粒颗粒灰岩、集合颗粒灰岩、含鲕粒的粒泥灰岩、泥晶灰岩和泥岩。根据碳酸盐岩微相特征及沉积相标志,在二叠系—三叠系界限附近划分出台地边缘、开阔台地和局限台地3种沉积相,其反映了二叠纪—三叠纪之交频繁的沉积相带变更的特点。该剖面碳酸盐岩微相反映的古生态和生物群落演替特征与中国华南同时期其他剖面具有较好的一致性,即二叠纪末生物大灭绝事件之后,早三叠世正常浅水碳酸盐岩台地生物类型和丰度极低,仅含有少量的双壳类、海百合等,灭绝事件界线附近以微生物碳酸盐岩等特殊微生物沉积构造占主导,之后微生物岩等消失,又出现了以双壳类为首的生物碎屑石灰岩。研究结果为了解二叠纪末生物大灭绝事件中生物和环境的协同演化提供了新的材料和认识。     

东秦岭陕西聂家沟剖面二叠纪—三叠纪之交沉积特征及其古环境意义*

东秦岭陕西镇安聂家沟地区二叠纪—三叠纪之交发育一套海相碳酸盐岩沉积序列,较完整地记录了二叠纪末生物大灭绝事件前后浅海碳酸盐岩台地相生物群落演替及环境变化等信息,是研究二叠纪末生物大灭绝事件前后生态环境变化与沉积响应的理想区域。通过碳酸盐岩微相分析方法,对陕西镇安聂家沟剖面二叠系—三叠系界线附近的碳酸盐岩生物组合和微相类型进行了详细分析,共识别出11个微相类型: 斑点状凝块石、叠层石灰岩、鲕粒—纹层状叠层石灰岩、有孔虫颗粒灰岩、藻—海百合泥粒灰岩、含有被包壳和被磨蚀骨屑颗粒的粒泥灰岩、鲕粒颗粒灰岩、集合颗粒灰岩、含鲕粒的粒泥灰岩、泥晶灰岩和泥岩。根据碳酸盐岩微相特征及沉积相标志,在二叠系—三叠系界限附近划分出台地边缘、开阔台地和局限台地3种沉积相,其反映了二叠纪—三叠纪之交频繁的沉积相带变更的特点。该剖面碳酸盐岩微相反映的古生态和生物群落演替特征与中国华南同时期其他剖面具有较好的一致性,即二叠纪末生物大灭绝事件之后,早三叠世正常浅水碳酸盐岩台地生物类型和丰度极低,仅含有少量的双壳类、海百合等,灭绝事件界线附近以微生物碳酸盐岩等特殊微生物沉积构造占主导,之后微生物岩等消失,又出现了以双壳类为首的生物碎屑石灰岩。研究结果为了解二叠纪末生物大灭绝事件中生物和环境的协同演化提供了新的材料和认识。     

川南观音场-瓦市地区须家河组六段储层特征及其控制因素

通过对4条野外剖面、40口并岩心样品及84张薄片的观察和测井等资料的分析,对川南观音场一瓦市地区须六段的岩石学特征、孔隙类型、孔隙结构及孔渗特征等进行了深入研究。结果表明：川南地区须六段岩性主要为中-细粒长石岩屑砂岩和岩屑石英砂岩,孔隙度在6％～10％之间,平均孔隙度为7．3％。渗透率为0．03×10^-3μm^2～0．9×1010^-3μm^2平均渗透率为0．177×1010^-3μm^2储层属于典型的低孔低渗储层,储集空间主要为粒间孔和粒内溶孔。在平面上,储层物性受沉积相带的控制;在垂向上,随深度的增加,压实作用和胶结作用使物性急剧变差。绿泥石的环边胶结作用、长石的溶蚀作用对储层物性起建设性作用,构造作用极大地改善了储层的物性。     

黄骅坳陷古近系沙河街组一段下部湖泊碳酸盐沉积相及其对油气分布的控制作用?

黄骅坳陷王徐庄油田古近系沙河街组一段下部厚40-50m，由碳酸盐岩与泥页岩互层组成，为湖泊中的碎屑岩-碳酸盐岩混积台地沉积。碳酸盐岩主要为石灰岩，其中包括亮晶颗粒石灰岩、泥晶颗粒石灰岩和泥晶石灰岩。颗粒主要为腹足类，也有鲕粒和内碎屑。根据沉积特征，混积台地可进一步划分为亮晶颗粒石灰岩滩、泥晶颗粒石灰岩滩和滩间等三种相。亮晶颗粒石灰岩滩为高能持续动荡环境，水深在正常浪基面之上，以亮晶颗粒石灰岩沉积为主；泥晶颗粒石灰岩滩为间歇动荡环境，水深在正常浪基面附近，以泥晶颗粒石灰岩沉积为主；滩间为安静低能环境，水深在正常浪基面之下，以泥晶石灰岩和页岩沉积为主。滩主要分布在台地边缘。同生断层的活动控制了台地的形成及滩的展布。亮晶颗粒滩是最好的储集相带，泥晶颗粒滩次之，滩间最差。油气分布主要受沉积相控制，高产井并不是位于构造高部位的滩间，而是位于低部位的亮晶颗粒石灰岩滩。     

斜长石溶蚀度：一种评价花岗质岩石风化度的新指标

本文提出了以标志性造岩矿物斜长石的显微孔隙变化为特征的风化度评价新指标——斜长石溶蚀度。该指标可以较好地反映全风化带（CDG）残积土风化度的精细变化，特别是风化程度在深度方向上的差异性。通过对香港CDG的实例分析，确定了三处残积土剖面的风化度相对大小。     

安塞油田长2油层成岩作用及其对储层物性的影响

安塞地区长2油层储层以中细粒长石砂岩为主，主要成岩矿物为绿泥石环边、方解石胶结物、石英和长石加大生长、伊利石、伊一蒙混层、钠长石和高岭石等。绿泥石环边的发育对原生粒间孔的保存起到有利的作用。石英加大级别达Ⅲ级，加大边含有丰富的有机包体，均一温度范围48．1～76．5℃，烃类进入储层的时间为早白垩世中期至晚白垩世。储层发育多种孔隙类型，面孔率平均为11．60％．主要类型有粒间孔、骨架颗粒溶孔和微裂缝等。残余粒间孔和骨架颗粒溶孔是本区长2储层的主要孔隙类型。根据成岩作用的矿物岩石学标志、有机质成熟度及古温度，将长2油层砂岩的成岩作用划分为3个成岩阶段：早成岩阶段、晚成岩阶段和表生成岩阶段。储层性质明显地受到沉积微相和成岩作用的影响，沉积物粒度较粗、厚度较大的分流河道储集物性明显优于各种粒度较细、厚度较薄的分流间席状砂体。     

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