岱崮地貌的基本特征、成因和演化

岱崮地貌是一种寒武系碎屑岩之上的平顶灰岩地貌,为中国五大地貌之一,对其研究具有地质学、古地理环境等科学意义。本文通过野外地质调查及室内研究,分析研究了岱崮地貌的特征、成因和演化,得出以下结论：1） 岱崮镇的崮主体呈NW向展布,由崮体和崮基组成。崮体包括崮顶、崮腰和崮底,崮顶为灰岩,崮腰和崮底以碎屑岩为主,崮基为前寒武系岩浆岩或太古宇泰山群;2） 近水平岩层是岱崮地貌发育的基础;3） NNW向、NW向和近EW向断层是岱崮地貌形成的根本因素,NW向和NE 向节理是主控因素,控制了岱崮地貌的走向、密度;4） 岱崮地貌古生代以来经历了多个时期的演化,经过加里东运动、海西运动和印支运动留存的寒武系-中奥陶统、上石炭统-二叠系是岱崮地貌形成的基础,燕山期中侏罗世末-晚侏罗世（162～149.8 Ma）、白垩纪（140～90 Ma）及喜马拉雅早期（65～43 Ma）产生的断层及节理是岱崮地。     

Geology and geochemistry of fault-hosted hydrothermal and sedimentary manganese deposits in the Oakover Basin,east Pilbara,Western Australia

Manganese mineralisation in the Oakover Basin is associated with Mesoproterozoic extension, basin formation and deposition of the Manganese Group. The underlying basement architecture of the Oakover Basin (a local half-graben geometry), inherited from the Neoarchean rifting event, plays an important role on the distribution, style and timing of manganese deposits. Fault-hosted manganese deposits are dominant along the ‘active’ faulted eastern margin, whereas flat-lying sedimentary deposits are dominant along the western ‘passive’ margin reflecting differences in ore-forming processes. The large number of significant manganese deposits in the Oakover Basin, previously thought to reflect a spatial association with Carawine Dolomite, more likely reflects the restricted nature of the Mesoproterozoic basin and development of a large reservoir of Mn²⁺ and Fe²⁺ in an anoxic zone of a stratified basin. Low O₂ conditions in the basin were caused by a paleotopographic high forming a barrier to open ocean circulation. The western margin sedimentary deposits formed later than the fault-hosted hydrothermal deposits along the eastern margin, once a significant reservoir of Mn²⁺ and Fe²⁺ had developed, and when there was sufficient subsidence to allow migration of the redox front onto the shallow shelf, with Mn precipitation on and within the seafloor sediments. The sedimentary manganese deposits are not uniformly distributed along the western edge of the basin; instead they are concentrated into discrete areas (e.g. Mt Cooke–Utah–Mt Rove, Bee Hill, Skull Springs and the Ripon Hills districts), suggesting a degree of structural control on their distribution. Fault-hosted manganese is observed beneath and adjacent to many of the sedimentary deposits. Marked geochemical differences are observed between the Woodie Woodie hydrothermal deposits and the sedimentary deposits. Woodie Woodie deposits display higher Ba, U, Mo, As, Sn, Bi, Pb, S and Cu than the sedimentary deposits, reflecting the composition of the hydrothermal fluids. The Al₂O₃ values of the Ripon Hills and Mt Cooke deposits are much higher than the Woodie Woodie deposits, reflecting the composition of the dominant host rock, as Al₂O₃ is typically <5 wt% in the Carawine Dolomite, but is >10 wt% in basal shale units of the Manganese Group. Highly variable Mn:Fe ratios (?5:1) in the hydrothermal manganese at Woodie Woodie reflects rapid deposition of Mn in and around fault zones. In contrast, slower accumulation of Mn oxides on and within the seafloor to form the large sedimentary deposits results in Mn:Fe ratios closer to 1:1 and elevated Co + Ni and REE values.     

柴达木盆地马海钾盐矿床沉积环境与开发

马海钾矿床是柴达木盆地内重要的盐类矿床之一。从盐类矿床沉积物的物相分析入手,着重揭示该成盐盆地沉积环境和古地理变迁特征,论述湖盆由形成、发展至老化衰亡的演变规律,反映了从上新世末期以来新构造运动在矿区地质构造上的典型表现,由这些成矿因素构建的矿床地质构造特征也得到总结。依照持续稳定发展的要求,就矿床开发过程中出现的急功近利局面,提出调整产品结构和重新布局开采对象的新策略,对企业生产实践具有指导意义。     

西昆仑-塔西南坳陷晚古生代以来的沉积构造演化

自柯克亚深层油气勘探取得突破以来,塔西南坳陷一直受到各类地质学家的广泛关注,有关该盆地的形成和演化历史及其油气资源评价近年来更是成为人们的研究热点.本文在总结前人资料的基础上,探讨塔西南和西昆仑地区自晚古生代以来所经历的构造及沉积格架的演变过程,对塔西南坳陷性质及其演化阶段划分所存在的争议进行了归纳,分析了塔西南-西昆仑这一盆山体系形成和演化中的构造变形和沉积记录.总体来说,根据现有沉积和构造变形资料,中生代之前西昆仑和塔西南坳陷分别处于同一构造背景下的不同沉积单元;二者之间盆山体系的形成主要自晚侏罗世-早白垩世,中-上新世是造盆造山作用机制发生重大转折的时期,或者说早更新世末的构造运动基本上奠定了西昆仑.塔里木盆地南缘现今的盆-山构造格架.     

上海地区第四承压含水层沉积环境及结构特征

上海地区第四承压含水层是地下水开发利用的主要层次,对其沉积环境、成因、结构特征进行深入研究有利于更好地开展地下水资源开发利用及地质环境保护工作.本文在对上海地区大量钻孔资料深入分析的基础上,对第四承压含水层形成时期即早更新世中、晚期沉积环境及含水层的成因进行了深入剖析,对含水层结构特征进行了详细刻画,为三维地质结构的建立奠定了基础.     

西天山阿吾拉勒一带侏罗纪生物组合和沉积环境

西天山阿吾拉勒一带侏罗系地层根据其岩石组合、生物组合面貌等特征,可分为下侏罗统八道湾组（J1b）、下侏罗统三工河组（J1s）和中侏罗统的西山窑组（J2x）,并在此基础上对侏罗纪地层的沉积环境进行分析,其为大陆裂谷衰亡之后河湖相沉积环境。     

兴文侵蚀型天坑的形成演化过程研究

According to the first-hand investigation and study on Xingwen Global Geopark,the results and the data show that apart from Dayanwan and Xiaoyanwan collapsed karst Tiankeng,there are other karst landforms in Bowang Mount scenic spot such as Feiwu Cave,Dao Cave,Cangshuiyan Gorge,Nanxing TanKeng and so on.These typical karst landforms could be regarded as different vestiges of erosive karst Tiankeng of Xingwen Global Geopark,which stand for the evolutional processes of erosive karst Tiankeng separately.Moreover,the evolutional processes of erosive karst Tiankeng could be divided into the following continuous processes:an erosive karst Tiankeng develops from the processes of eroding and dissolving & extending of silo Sinkhole,and subsequently degrades to a large gorge or doline.It is worth pointing out that except for erosion of flowing water,at the same time,collapse effect has been playing extremely important role in the forming processes of these special erosive landforms.     

Pacific superplume-related oceanic basalts hosted by accretionary complexes of Central Asia, Russian Far East and Japan

Plume-related oceanic magmatism form oceanic islands, seamounts and plateaus (hereafter “seamounts” or “paleoseamounts”), which are important features in geological history. The accretion of oceanic seamounts to active continental margins significantly contributed to the formation of the continental crust. This paper reviews occurrences of Late Neoproterozoic–Mesozoic seamounts of the Paleo-Asian and Paleo-Pacific oceans, which are hosted by accretionary complexes (ACs) of Russian Altai, East Kazakhstan, Mongolia, Russian Far East and Japan. The paleoseamounts commonly consist of Ti–LREE–Nb-enriched plume-related basalts (OIB-type or intraplate basalts) capped with massive limestone and associated with other units of oceanic plate stratigraphy (OPS): oceanic floor basalts (MORB), pelagic chert, epiclastic slope facies, etc. The paper presents available geochemical data on the plume-related basalts including the first geochemical data on the Middle Paleozoic OIB-type basalts of the Paleo-Asian Ocean hosted by the Ulaanbaatar AC of Mongolia. An emphasis is made for the structural setting of OPS units, specific geochemical features of intraplate basalts, problems of their identification, and distinguishing from magmatic units of a different origin such as MORB, island-arc and back-arc basalts. Finally, we propose a continuous, though periodical, evolution of the Pacific superplume-related magmatism, which can be more reliably proved by studying Middle Paleozoic OPS units hosted by ACs of Mongolia and Tien Shan, and discuss prospects of future studies.     

Tectonic and climatic controls on late Quaternary bajada sedimentation along Narmada-Son Fault(NSF),Gujarat,Western India

An alluvial bajada has been recognized along a part of the active Narmada-Son Fault(NSF) and confined by the Karjan River on the eastern side and by the Madhumati River on western side.The bajada sequence exposed along the incised cliffs of various north flowing parallel streams has been studied in their proximal,medial and distal part. The sediments are characterized on the basis of grain size,fabric,sedimentary structures,bed geometry and sorting, and lithologs prepared from the mapped cliff sections.Detailed study of sedimentary characteristics,lithofacies analysis and facies associations indicate that sediments are mainly of three types-sediments that were deposited by debris flows and sediment gravity flows,and as extensive bar deposits.Three major aggredational sequences are recognized.Each sequence is composed of coarsening-upward sequence of proximal facies overlain by fining-upward sequence of distal facies.Coarsening upward sequence record periods of tectonic activity related to uplift along the NSF and fan progradation,whereas fining-upward sequence results from tectonic quiescence periods.The presence of rhizocretions,calcium carbonate nodules and calcite sheets within the basal debris flow and sediment gravity flow indicate semi-arid climate,whereas the formation of pedoginized paleosol indicate relatively wetter climate prevailing in the study area.Tectonic activity along the NSF has played dominant role by controlling the geometry and volume of bajada sediments.Climate is found to be responsible for compositional and temporal distribution of bajada sediments.OSL dating suggests that the bajada sediments were deposited during the later part of late Pleistocene.The incision of the sediments is attributed to uplift due to inversion of the lower Narmada basin during the early Holocene.     

Mesh grading approach for wave propagation in high velocity-contrast media

A mesh grading approach based on investigated lump method has been presented for simulating wave propagation in high velocity-contrast media. Unstructured fine grids are used to discretize the low wave-velocity medium in order to ensure the accuracy of numerical computation, and unstructured coarse grids are used for the high wave-velocity medium in order to substantially reduce the computational cost. On the interface, one coarse grid can match the fine grids of arbitrary odd number. The key feature of the proposed method is the constructions of investigated lumps on the interfaces of media. The transition zone, which is commonly used in the discontinuous grid scheme based on the staggered-grid finite-difference method, will not be used any more. Moreover, the computational instability that the discontinuous grid schemes frequently encountered does not arise in the proposed method. The comparisons with the analytical solutions and the application in studying the effects of sedimentary basin demonstrated that the mesh grading approach is a valid, accurate, convenient and flexible algorithm in simulating wave propagations in high velocity-contrast media with irregular interfaces.