Geochemistry and origin of rare earth elements (REEs) in the Shengli River oil shale, northern Tibet, China

The Shengli River-Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. Twenty-eight samples including oil shale, micritic limestone and marl were collected from the Shengli River area to determine the contents and distribution patterns of rare earth elements (REEs) in marine oil shale. Oil shale samples from the Shengli River area have high ash yield (61.86–67.48%) and TOC content (8.02–13.67%) with low total sulfur (S_t,d) content (0.76–1.39%) and intermediate shale oil content (3.60–16.30%). The total rare earth element (ΣREE) content in oil shale samples is notably depleted (46.79–67.90 μg/g), approximately one third of the mean value of the North American Shale Composite (NASC), and lower than that of world-wide black shales and Chinese coals, but higher than that of world-wide coals and micritic limestone samples (29.21 μg/g) from the Shengli River area. The oil shale samples from the Shengli River area exhibit shale-like Chondrite or NASC-normalized REE patterns similar to those of micritic limestone and marl samples from this area, indicating that REEs of these different lithological samples may have been derived from a similar terrigenous source.REE contents of oil shale samples are highly positive correlated with ash yield and show a positive correlation with Fe and a weakly positive correlation with organic sulfur, and the vertical variations of REEs mainly follow those of Si, Al, K and Ti. All these facts indicate that the REE contents in oil shale seams are mainly controlled by clay minerals and, to a lesser extent, by pyrite, as well as partly associated with oil shale organic constituents. Rare earth elements in the Shengli River oil shale have originated from two sources: a felsic volcanic rock source and a clastic or/and limestone source.     

内蒙古赤峰红花沟原太古宇中的微体化石及其意义探讨

本文报道了在内蒙古赤峰市红花沟石头道村东山，原认为属太古宙的地层中所发现的多门类微体化石群，其大地构造位置的华北地台北缘内蒙地轴东部。化石群包括见于我国南方寒武世梅树阶的软舌螺类，似软舌螺类，棱管壳类，齿形壳类，开腔骨类，原牙形刺类，单板类，球形壳类，口盖化石等；也有本区特有蠕虫管类及藻类化石，共计２０属２０种（其中２新属３新种，１相似种，１０未定种）证明该区原太古宇中的部分地层时代应属晚震旦世一     

长江三峡工程库首区地壳稳定性模糊数学综合评价

地壳稳定性是指一定时期、一定地域内地质体(包括深部地质体和表层岩土体)的稳定程度, 它受地壳结构构造、各种地质作用与工程建设相互作用等的综合影响, 具有综合模糊概念, 本文试图运用模糊数学进行长江三峡工程库首区地壳稳定性定量化综合评价。     

白云鄂博铌、稀土铁矿的成矿地质条件及矿床成因

白云鄂博矿区的铁矿和铌、稀土矿分属两个成矿期和两种不同的成因。铁矿是中元古界蓟县系哈拉霍疙特组内的层控受变质铁矿，赋存在宽沟南侧的层状白云岩中，该白云岩及铁矿层是在两条同生断裂所控槽状泻湖中沉积的。除白云岩外，宽沟南北两侧地层均可对比，同属白云鄂博群。铁矿层的原生矿物为以菱铁矿为主的FeCO3－MgCO3系列矿物，受后期侵入岩的热变质作用转变为磁铁矿及赤铁矿。铌、稀土成矿作用与脉状、瘤状碳酸岩有关。矿区已发现该类脉岩40余条，可分为白云石质及方解石质两类，以前者为主。两类碳酸岩的稀土元素特征均为轻稀土高度富集型，铕弱亏损到富集，其来源较深碳酸岩体沿断裂侵入造成强烈而广阔的碱交代蚀变带，以霓长石化为主，其强度与稀土矿化强度呈正相关关系。推测矿区在不大的深度内赋存有较大的隐伏碳酸岩侵入体。     

Fluvial sequence pattern and its response of geomorphy in depression phase of rift basin: A case study of the Lower Member of Neogene Minghuazhen Formation in Shaleitian Uplift area,Bohai Bay Basin

The sequence classification is a difficulty of sequence stratigraphic study on rivers that are distal to coast area during the depression phase of rift basin. Based on the integrated analysis of logging,cores and seismic data,the case study shows that the Lower Member of Neogene Minghuazhen Formation in the Shaleitian Uplift area in the western Bohai Sea region corresponds to one complete third-order sequence which can be divided into four fourth-order sequences(i.e. SQm1-SQm4). Sedimentary hiatus,wide and shallow incised valley and amalgamated channel sand bodies are the main recognition of sequence boundaries in fluvial sequence stratigraphy of the study area. Each fourth-order sequence comprises low and high accommodation systems tracts. According to seismic sedimentological and quantitative geomorphological analysis,low-sinuosity rivers including braided river and low-sinuosity meandering river are well developed in the low accommodation systems tract,whereas the medium- to high-sinuosity meandering rivers are well preserved in the high accommodation systems tract. The change in the new creation of accommodation and the sediment supply exert a significant control on the stacked pattern within different systems tracts.     

什么控制了华北克拉通东部在新近纪的构造活动?

在新近纪初期(约23 Ma)的时候,在当时中国大陆周边板块构造环境没有发生重大变化的情况下,华北克拉通东部构造活动性质仍发生了明显的变化.比如,华北克拉通东部的岩石圈增厚了,唐山-邢台断裂开始活动的同时太行山山前断裂却变得不活跃了,华北局部构造变形性质发生了变化等.虽然在古近纪和8 Ma以后,有证据显示印度-欧亚大陆的...     

中国高分辨气候记录与全球变化

2001年第一届全国高分辨率气候记录会议提出,用3～5年时间,建立几个较长的可靠的高分辨气候记录。文章介绍了经过几年的努力工作已经获得的数个千年及更长的记录,这些记录数据多已在世界数据中心向科学家公开并很快为科学界引用,从而结束了国际高分辨气候记录数据库极少中国千年气候重建数据的历史;通过对比最近2000年来中国的高分辨气候记录和北半球其他高分辨记录,发现数个世纪的缓慢变冷紧随世纪尺度快速变暖的气候变化模式至少在半球范围是准千年重现的,这一结果指出,我们应该从更长时间跨度的气候旋回自然背景来诊断20世纪的快速变暖     

塔里木盆地轮南奥陶系古潜山油气成藏与分布

轮南奥陶系碳酸盐岩古潜山形成于晚加里东-海西期,经过多期构造运动的改造,形成了现今的构造格局;经过了多期成藏过程,形成了现今复杂的油气水分布特征.轮南奥陶系古潜山油气主要分布在潜山围斜部位,潜山面以下约150 m范围内,原油分布不受局部构造影响.总体看来,轮南奥陶系古潜山油气分布主要与储集空间的分布、水动力作用和差异聚集作用有关;轮南奥陶系古潜山油水界面是倾斜的,油气藏具有一定的水动力特征,可能是一个大型的水动力圈闭油气藏.     

四川盆地下寒武统龙王庙组浅水碳酸盐岩台地沉积相特征及模式*

准确建立四川盆地龙王庙组沉积模式和精细刻画颗粒滩时空分布规律,是提高天然气勘探成功率的关键。依据野外露头、钻井、测井和地震等资料,综合分析四川盆地及周缘下寒武统龙王庙组沉积相类型及特征;以四级层序为单元,精细刻画等时地层格架内沉积相时空展布特征,建立沉积模式,揭示颗粒滩发育规律,指出下一步天然气勘探方向。结果表明: (1)四川盆地及周缘龙王庙组发育典型浅水碳酸盐岩镶边台地沉积体系,自盆地西缘向东依次发育混积潮坪、局限台地(颗粒滩、云坪和咸化潟湖等微相类型)、开阔台地(颗粒滩、灰坪等微相类型)、台地边缘和斜坡—盆地等沉积相类型;(2)建立了“一凹两隆,双滩成带”的沉积模式,颗粒滩的发育主要受控于古地貌和相对海平面升降,具体表现为垂向上主要发育于四级层序海退时期,平面上沿台地边缘带和围绕咸化潟湖的相对隆起区呈带状分布。由于颗粒滩是优质储集层发育的有利相带,因此该结果可为四川盆地寒武系龙王庙组下一步天然气勘探提供沉积地质基础。     

鄂尔多斯奥陶纪古构造

用野外露头剖面、钻井剖面和地震剖面相结合的研究方法,对鄂尔多斯地区奥陶系213条共长8317 km的地震剖面行了重新处理和地层解释,这大大提高了解释精度。以此为基础,把鄂尔多斯奥陶系划分为10个地层单位,即冶里组、亮甲山组、马家沟一组、马家沟二组、马家沟三组、马家沟四组、马家沟五组、马家沟六组、平凉组和背锅山组,并绘制了它们的等厚图。从这些图可以看出,冶里期和亮甲山期的古构造格局为“一隆三凹”,即西缘凹陷、南缘凹陷和东缘凹陷呈“U”字形包围着一个中部隆起。到马家沟一期至六期,“一隆三凹”的古构造格局仍然基本上保持着,尽管其隆起和凹陷的形状、大小和位置均有所变化。到平凉期,古构造格局为“一隆二凹”,即西缘凹陷和南缘凹陷呈“L”形镶嵌在一个巨大的鄂尔多斯隆起的西缘和南缘。到背锅山期,古构造格局为“一隆一凹”,即一个残留的西南缘凹陷位于一个更加庞大的鄂尔多斯隆起的西南缘一隅。到奥陶纪末,鄂尔多斯地区以及整个的华北地台均变为隆起区,从而结束了鄂尔多斯地区隆起与凹陷并存的古构造格局。