动物碎屑反射率作为源岩成熟度指标的有效性和局限性探讨

综述了笔石,几丁虫,虫牙等动物碎屑的时空分布、光性特征及影响动物碎屑反射率的因素。由于下古生界源岩中缺乏能表征成熟度指标的镜质体,使得动物碎屑反射率无法与目前国际上公认的成熟度指标－－镜质体反射率直接进行对比,而得利用ＣＡＩ、红外参数及沥青反射率等中间媒介质间接地与镜质体反射率进行对比,由此建立起的动物碎屑反射率与镜质体反射率的对应关系的准确程度就受到一定影响。同时由于动物碎屑分布层位有限及本身光     

新疆中生代煤中半镜质组特征及其研究意义

通过分析显微图像的光学性质和测定煤的反射率等方法,研究了新疆中生代煤中半镜质组特征。结果表明:新疆中生代煤中含有一定量的半镜质组;均质半镜质体占总体(均质镜质体与均质半镜质体之和)的49%~64%,均质半镜质体的最大反射率(R_max)比均质镜质体的高0.08%~0.13%;均质半镜质体的R_max介于均质镜质体和结构镜质体之间,结构半镜质体的R_max比结构镜质体的高0.28%~0.34%。由此可以得出:在三大组分划分方案中,应将均质半镜质体归入镜质组的均质体中,同时认为,按显微组分三大组分划分方案中,将结构半镜质体归入惰质组的半丝质体中更合理;在测定煤的反射率时,不能将均质半镜质体作为反射率的测定对象。本项研究结果对于指导本地区煤炭的炼焦配煤、煤炭液化和深加工利用等具有重要意义。      

海侵对镜质体反射率值的影响

在成熟度研究中,镜质体反射率是应用最广泛的参数。但是,也有越来越多的文章指出,反射率值还受沉积区地热历史以外的其它因素所影响。对反射率这种变化的解释,包括类脂物(细菌、藻类)在镜质体基质中的存在、原始植物组成的差异及沉积微环境的差异。煤和泥炭中     

镜质体反射率测定结果的影响因素

简要回顾了镜质体反射率测定的发展过程,概括了镜质体反射率在石油地质中的应用及存在的问题,重点探讨影响镜质体反射率测定的因素。这些因素既有地质的,也有人为的,包括:镜质体本身的局限,烃源岩有机质类型、岩性,样品采集与处理过程以及测定环节4个方面。镜质体反射率测定结果正是这些因素相互作用的体现。针对上述影响因素,提出几点建议,供有关研究人员参考。      

准噶尔盆地北部燕山中期古地温梯度恢复

运用磷灰石裂变径迹(AFT)法和镜质体反射率(Ro)法恢复了准噶尔盆地北部燕山中期的古地温梯度。研究结果显示,磷灰石裂变径迹(AFT)恢复的古地温梯度分布在3.5~3.9℃/hm;镜质体反射率(Ro)恢复的古地温梯度接近4.0℃/hm;平均接近3.7℃/hm,明显高于2.3℃/hm的现今地温梯度。准噶尔盆地北部燕山中期较高古地温场背景不仅对烃源岩热演化研究具有重要意义,同时也指示了准噶尔盆地北部存在一次燕山中期构造热事件。     

镜质体、海相镜质体和镜质体反射率及其研究实例

镜质体是一种由高等植物木质素经过生物化学降解作用和凝胶化作用形成的胶状体,在煤和炭质泥页岩中含量高,仅出现在志留纪及其以后的地层中。此外,还有一种海相镜质体,主要由海洋低等生物(藻类、菌类及某些海洋低等动物)经腐殖化作用而形成,主要存在于早古生代及晚古生代页岩和碳酸盐岩地层中。研究表明,海相镜质体反射率(R~o_m)可作为成熟度指标加以应用。海相镜质体成熟作用轨迹不同于镜质体,二者存在一定的相关关系,使用时需把海相镜质体反射率换算为镜质体反射率(R_o)。镜质体反射率是一个寻找隐伏岩体的好方法,作者采用镜质体反射率方法对铜陵地区开展了研究,初步结果表明,铜陵地区全部数值均超过地热增温率理论曲线,说明铜陵地区深部可能有较大的隐伏岩体,深度大约在4~5 km左右。此外,在ZK113号钻孔深度200~260 m处R_o很高(2%~3%),可能预示钻孔旁侧有规模较小的隐伏侵入体,推测距钻孔距离不超过100 m,但具体方位不详。上述研究表明采用镜质体反射率方法寻找隐伏岩体是可行的,它的最大优点是解释的唯一性,R_o数值仅与温度有关,不受其他因素的干扰。     

甲基双金刚烷成熟度指标讨论与应用

甲基双金刚烷化合物可用于镜质体反射率R在1．0％-2．0％间的原油及烃源岩成熟度的研究,在该成熟度范围内甲基双金刚烷成熟度指标与镜质体反射率之间具有良好的线性关系。对甲基双金刚烷成熟度指标研究成果的分析表明,甲基双金刚烷成熟度指标与镜质体反射率的线性关系明显受烃源岩岩性的影响,对于碳酸盐岩和泥岩,它们的线性关系有较大差别;对于不同地区碳酸盐岩,它们的线性关系十分接近,但对于不同地区泥岩,它们的线性关系则差别较大。资料反映甲基双金刚烷成熟度指标适合用于中-高成熟度原油的成熟度研究,应用范围的Ro下限值为1．0％-1．3％,Ro上限值为2．0％。运用甲基双金刚烷成熟度指标对珠江口盆地番禺低隆起地区轻质原油成熟度的研究表明,该地区轻质原油为高成熟度原油,Ro值在1．3％以上。     

吐哈盆地煤成烃主要贡献组分剖析

吐哈盆地中下侏罗统煤显微组分组成显示了“碎、小、薄”和过渡组分含量高的特点。结合显微和超微层次有机岩石学分析，在显微组分层次生烃组分主要为基质镜质体，碎屑类脂体、薄壁角质体、木栓质体和小孢子体在煤成烃中也有一定的贡献；超微层次生烃组分主要表现为分布于基质镜质体中的超微类脂体。煤中基质镜质体的高含量弥补了其单位生烃潜力低的不足，基质镜质体富氢成因在于生物化学阶段细菌等微生物对其强烈降解改造作用。     

窑街矿区海石湾井田油A层腐泥煤有机质成熟度辨析

在石油、天然气、页岩气和煤层气资源勘探开发方面,镜质体反射率指标被公认是唯一可对比的烃源岩有机质成熟度评价指标。为准确测定窑街矿区海石湾井田油A层腐泥煤的有机质成熟度,采集井田钻孔煤岩样品,开展显微镜下显微成分反射光、荧光光学特征观测。测试发现,油A层腐泥煤中存在2种不同特征镜质组,一种为发荧光的镜质组,反射色低、反射率测值低;另一种为不发荧光镜质体,反射色高、反射率测值相对偏高。油A层沉积环境分层明显,上部为腐泥煤,显微成分以藻类体为主,含有大量的黄铁矿,反映深部沼泽强还原环境;下部显微成分以腐泥基质、基质镜质体、角质体为主,相较于上部,藻类体及黄铁矿含量明显降低,反映出其沉积物源发生变化,藻类等低等生物输入比例降低,高等植物物源比例增高,反映为相对较弱的还原环境。根据井田地层沉积环境、油A层腐泥煤显微组成及其与下部煤二层腐植煤的镜质组成熟度对比分析,认为油A层腐泥煤中不发荧光镜质体的反射率能够反映其真实的成熟度,与下部煤二层处于同一变质阶段。研究认识为开展腐泥煤有机质成熟度分析提供了新的方法、思路,当煤岩层中高等植物含量较少,或者与其相邻地层成熟度差异较大时,建议将局部测试结果与整个煤系各煤/岩层进行比对,同时结合其镜质体荧光特征和沉积环境综合判断分析。      

台湾海岸山脉同造山盆地古热流值的估算:基于镜质体反射率约束下的一维盆地模拟

台湾东部海岸山脉上新世-更新世同造山盆地记录了北吕宋岛弧与欧亚板块之间的斜向碰撞过程。目前关于该盆地的构造属性存在着两种绝然不同的认识,即“热”的弧前盆地和“冷”的碰撞盆地。本文采集了海岸山脉南部泰源向斜西翼更新统八里湾组泥岩样品,测量了其有机质的镜质体反射率(Ro)。Ro测量值的最小值、最大值和平均值与相对埋深之间的相关系数分别是0.76、0.43和0.67,反映出样品中同生镜质体在数量上远超过原生镜质体。由于同生镜质体和原生镜质体无法简单区分,本文将最小值和平均值分别作为原生镜质体平均镜质体反射率的下界和上界,采用一维盆地模拟技术计算出在给定剥蚀厚度和热流值的范围下的理论镜质体反射率。通过对比理论和实测镜质体反射率,我们发现:(1)八里湾组所有地层段与中段、上段在镜质体反射率(R_o)的偏差上具有不同的特征,意味着在中段开始沉积时下段卷入到褶皱冲断带中;(2)对于上段获得盆地剥蚀厚度解的下限是3.2～4.8 km,对应的热流值小于0.68～1.00 HFU(36.84～41.87 mW/m²),表明同造山盆地是一个“冷盆”。     

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

正~~     

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