陕北典型地区乡村聚落水蚀泥沙规律的初步研究

通过定位观测资料的分析,发现陕北多沙粗沙区乡村聚落的平均年侵蚀强度达5434.3t/km2,户间道路、户间空地、庭院的平均侵蚀强度分别达7348t/km2.6873.2 t/km2,2081.7t/km2.除庭院属轻度级侵蚀外,其它已达强度级侵蚀.同时延安的户间道路(14190.8t/km2),榆林的户间空地(13547.4t/km2),已达极强度侵蚀.应加强研究和防治.水蚀泥沙的粒度以0.01～0.05 mm的粗粉沙和0.001～0.005 mm的粘粒为主,分别占到43.98%和19.81%,≥0.05mm的粗泥沙含量明显小于聚落以外的坡面,而且区域变化比较明显,从南到北,细粒成分愈来愈少,粗粒成分越来越多;与土壤粒度相比,粗泥沙水蚀系数在庭院、户间道路、户间空地分别达到0.54,0.55,0.75,平均为0.61.     

重力驱动作用——滦平盆地下白垩统西瓜园组沉积时期主要的搬运机制

通过对冀北滦平盆地下白垩统西瓜园组沉积地层的实地考察,发现盆地内发育丰富的重力驱动作用沉积物。文中描述西瓜园组发育的滑动和滑塌现象,指出露头剖面中存在的挤压变形现象并非构造成因,而是由于滑动块体和滑塌块体前端的挤压应力环境造成的。在介绍西瓜园组重力流沉积发育环境的基础上,对露头中存在的若干重力流沉积进行了描述,并使用砂质碎屑流这一概念对这些现象进行了较为合理的成因解释。通过对滑动和滑塌(重力块体运动)和砂质碎屑流—浊流(重力流)沉积物研究,结合前人对该地区冲积扇—扇三角洲的研究成果,认为重力驱动作用是滦平盆地下白垩统西瓜园组沉积时期主要的搬运机制。     

大兴安岭巴雅尔吐胡硕地区碎斑熔岩锆石U-Pb年龄、地球化学特征及其地质意义

在大兴安岭中南段巴雅尔吐胡硕地区发现一套碎斑熔岩。根据野外调查,可分为中心相的细微粒斑状石英二长岩(-石英二长斑岩)和边缘相的英安流纹质碎斑熔岩。通过SHRIMP锆石U-Pb测年,获得细微粒斑状石英二长岩的年龄加权平均值为137.4±0.9Ma(MSWD=1.13),英安流纹质碎斑熔岩的年龄加权平均值为135.2±0.8Ma(MSWD=1.17),二者的形成时代均属于早白垩世早期。由元素地球化学分析可知,6件样品均属于过铝质的高钾钙碱性A型花岗岩,且具有完全一致的微量元素蛛网图和稀土元素配分曲线,均具有明显的负Eu异常,均富集大离子亲石元素Rb、Pb和轻稀土元素,亏损高场强元素Nb,Th较富集,Ba、Sr、Eu具有一定亏损,Pb强烈富集,表明岩石来源于地壳部分熔融。在构造环境判别分析的基础上,提出研究区碎斑熔岩属于碰撞后或造山期后的张性构造环境花岗岩(A2型花岗岩),形成于拉张环境,代表了伸展的大地构造背景。结合大兴安岭地区的大地构造演化特征,其形成与蒙古-鄂霍茨克闭合造山后的岩石圈伸展作用有关。     

柴达木盆地北缘侏罗系不同沉积环境烃源岩生物标志物特征及其应用

柴达木盆地北缘地区侏罗系(中下侏罗统)的优质烃源岩主要发育于湖相与三角洲相环境。研究了不同时代、不同沉积环境中烃源岩的生物标志物组成特征,结果发现,有3类化合物的分布与组成差异显著,包括三环萜烷(C19、C20、C21)的分布型式、重排藿烷的丰度以及规则甾烷的相对组成。其中,不同时代的差异主要体现在规则甾烷组成上;而不同沉积环境的差异主要体现为三环萜烷(C19、C20、C21)的分布型式及重排藿烷的丰度。分析认为,这些差异与烃源岩的沉积环境及其生源组成有密切关系。据此,初步将这些参数应用于两方面研究,一是为划分地层沉积环境提供“生物标志物相标志”,二是研究油源对比,取得良好效果。因此,本文研究结果具有重要实用价值与参考意义。     

Rb–Sr dating of sulfides and S–Pb isotopic study of the Bayanbaolege Ag polymetallic deposit,Inner Mongolia,NE China

The large-scale Bayanbaolege Ag polymetallic deposit is situated in the Tuquan–Linxi Fe-Sn-Cu-Pb-Zn-Ag metallogenic sub-belt in eastern slopes of the southern Great Xing’an Range, NE China. The sulfide-quartz vein-type orebodies in the deposit are hosted primarily in the Early Cretaceous granodiorite porphyry and Late Permian strata. Three primary paragenetic stages of veining have been identified: (I) arsenopyrite- pyrite-quartz stage, (II) pyrite-sphalerite-quartz stage, and (III) galena-silver minerals (pyrargyrite, argentite, and pearceite)-calcite stage. The Rb–Sr dating of sulfides yielded an isochron age of 129.9 ± 2.9 Ma (MSWD = 2.1) for the sphalerite, which constrains the mineralization age to the Early Cretaceous. Rb and Sr concentrations in the sulfides ranged from 0.0940 to 1.0294 ppm and 0.0950–3.3818 ppm, respectively. The initial ⁸⁷Sr/⁸⁶Sr value of the sphalerite was 0.70852 ± 0.00018, indicating that the mineralized materials were derived from the mixed crust-mantle source area. S isotope analysis showed that the δ³⁴S values of the sulfide samples varied in a narrow range, from −1.5‰ to +1.3‰ (mean −0.65‰), indicating a magmatic S source. Pb isotopic ratios of the sulfides (²⁰⁶Pb/²⁰⁴Pb = 18.306–18.416, ²⁰⁷Pb/²⁰⁴Pb = 15.524–15.605, ²⁰⁸Pb/²⁰⁴Pb = 38.095–38.479) and the granodiorite porphyry (²⁰⁶Pb/²⁰⁴Pb = 18.341–18.933, ²⁰⁷Pb/²⁰⁴Pb = 15.539–15.600, ²⁰⁸Pb/²⁰⁴Pb = 38.134–38.944) reflect that the ore-forming materials originated from contemporaneous magma with Early Cretaceous granodiorite porphyry. This study of the Bayanbaolege deposit and other hydrothermal deposits in the area provides compelling evidence that the widespread Mesozoic magmatism and mineralization in the southern Great Xing’an Range occurred in an intracontinental extensional tectonic setting, which was associated with the westward subduction of the paleo-Pacific plate.     

辽西义县组叶肢介化石在冀北滦平盆地西瓜园组中的系统发现及其意义

冀北滦平县西瓜园南李营剖面是西瓜园组的命名剖面,自下而上可划分为西瓜园组一至四段,为一套单一岩相的沉积岩。在火斗山乡马圈子,西瓜园组以一层水下分流河道砾岩与其下伏大店子组四段为连续沉积,拉海沟马圈子剖面为西瓜园组与大店子组的界线层型。西瓜园组自下而上可连续划分为5个叶肢介化石带,与辽西义县组尖山沟层、老公沟层一金刚山层的叶肢介组合完全可以对比．义县阶的单位层型应以西瓜园组为层型剖面,原定义县阶的单位层型马神庙一宋八户标准地层剖面仅能作为义县阶的副层型。由于辽西义县组尖山沟层至金刚山层的叶肢介化石在冀北西瓜园组中的系统发现,冀北地区西瓜园组与辽西义县组完全可以对比,从而解决了30余年来冀北辽西晚期中生代地层的对比问题,具有重要的地层意义。     

苏北地区老井复查测井综合评价技术及方法研究

随着苏北小油田勘探开发程度的提高,非常规储层日益成为重点勘探开发的对象。苏北地区老井测井资料复查,立足现有的常规测井资料,结合测试等资料,通过扎实的基础工作和测井评价技术和分析方法的进步和提高,重点在干、密、水、无中全方位找油,并对以往相对忽视和评价认识手段方法相对不足的低孔渗储层、特殊含灰低孔渗储层与低阻油层作为重点研究分析对象,对测井资料进行全面复查评价,取得了良好的油气成果。     

Characteristics and evolution of lacustrine turbidite of Chang-7 Member of Yanchang Formation in northern Shaanxi

Lacustrine turbidite of Chang-7 Member in the studied area consists of sihstone and fine sandstone with respect to grain size, which is feldspathic lithie sandstone, syrosem arkose and arkose with respect to mineral constitution affected by provenance. There are such apparent signatures as lithology, sedimentary structure, sedimentary sequence and well logs, to recognize turbidite. During the paleogeographic evolution of Chang-7 Member, lake basin and deep lake are both at their maximum extent during Chang-73 stage, resulting in the deposition of Zhangjiatan shale with widespread extent and of turbidite with fragmental-like. Deep lake line is gradually moving toward lake center and turbidite sand bodies are gradually turning better with better lateral continuity, connectivity and more thickness, from stages of Chang-73, Chang-72 and Chang-7t, which can be favorable reservoir in deep-water.     

新疆北部大地构造研究中几个问题的评述——兼论地质图在区域构造研究中的重要意义

地质图是区域地质和大地构造研究的重要基础资料,认真研读地质图是大地构造学研究的重要途径。以新疆北部几个重要构造带为例,展示了地质图的分析、研读在大地构造研究中的重要意义。基于地质图分析并结合最新的研究资料,认为东准噶尔卡拉麦里造山带的碰撞时限不晚于早石炭世(370~340Ma);西准噶尔达拉布特构造带形成于石炭纪晚期,该带不具有板块边界或者俯冲-缝合带的属性;以巴音沟蛇绿岩带为代表的北天山洋盆的缝合时限在晚石炭世(325~316Ma)。由此推断,新疆北部地区洋盆俯冲和地体拼贴碰撞造山过程应该在晚石炭世之前完成。     

Identification of geologic contrasts from landscape dissection pattern: An application to the Cascade Range, Oregon, USA

This paper demonstrates the plausibility of inferring the spatial variability of geology from topographically derived landscape dissection patterns. This enables surveying large regions for spatial variability in geology, for which direct remote sensing is not feasible, by studying variability in dissection pattern, a feature extracted straight off from digital elevation model data. Dissection pattern is obtained automatically by a novel algorithm, especially designed to delineate the valleys with high accuracy in order to reflect spatial variability in dissection density. The dissection pattern is encapsulated by a continuous map of drainage density, a raster variable best suited for showing spatial variability of dissection. Such a map, constructed for the study area in the Cascade Range, Oregon, USA, shows a sharp discontinuity in the dissection pattern, indicating change in underlying geology. Possible factors controlling the dissection pattern such as climate, local and regional slopes, vegetation, and geology are examined, and geology has been found to be the dominant controlling factor. The dissection contrast coincides with the boundary between the Western and High Cascades, two geologic provinces with different rock ages and types. The older and less permeable Western Cascades are associated with denser dissection pattern, whereas the younger and more permeable High Cascades correspond to less dissected pattern. This new mapping method can be applied to locations where topography is the only readily available data, and the generated map could be used to extract previously unknown geologic or environmental information.