Upper bound finite element analysis of slope stability using a nonlinear failure criterion

In this study, upper bound finite element (FE) limit analysis is applied to stability problems of slopes using a nonlinear criterion. After formulating the upper bound analysis as the dual form of a second-order cone programming (SOCP) problem, the stress field and corresponding shear strength parameters can be determined iteratively. Thus, the nonlinear failure criterion is represented by the shear strength parameters associated with stress so that the analysis of slope stability using a nonlinear failure criterion can be transformed into the traditional upper bound method with a linear Mohr–Coulomb failure criterion. Comparison with published solutions illustrates the accuracy and feasibility of the proposed method for a simple homogeneous slope stability problem. The proposed approach is also applied to a seismic stability problem for a rockfill dam to study the influence of different failure criterions on the upper bound solutions. The results show that the seismic stability coefficients obtained using two different nonlinear failure criteria are similar but that the convergence differs significantly.     

Upper Ocean Response and Feedback Mechanisms to Typhoon

This paper is an introduction to a new project of the national basic research program of China, “Upper Ocean Response Feedback Mechanisms to Typhoon”. The importance and necessity of this project, regarding the national interests, are discussed at the beginning. Then, the ocean typhoon interaction is proposed as a cutting-edge research topic, in terms of the physical mechanism, data assimilation method, and forecast technique. Latest research progresses are reviewed on the oceanic response and feedback to typhoon, the large scale interaction between the ocean and typhoon, the multi source ocean data assimilation related to typhoon, and typhoon forecast model. Finally, the key scientific questions and the major research contents are presented. bstract: This paper is an introduction to a new project of the national basic research program of China, “Upper Ocean Response and Feedback Mechanisms to Typhoon”. The importance and necessity of this project, regarding the national interests, are discussed at the beginning. Then, the ocean typhoon interaction is proposed as a cutting-edge research topic, in terms of the physical mechanism, data assimilation method, and forecast technique. Latest research progresses are reviewed on the oceanic response and feedback to typhoon, the large scale interaction between the ocean and typhoon, the multi source ocean data assimilation related to typhoon, and typhoon forecast model. Finally, the key scientific questions and the major research contents are presented.     

苏北盆地上白垩统—第三系页岩油气成藏层位及有利区带

苏北盆地上白垩统—第三系分布广,地层完整。其中泰州组二段、阜宁组二段和阜宁组四段泥页岩发育,厚度为100～250m,有机质丰富,有机碳一般大于1.0%,演化程度高,并在泥页岩中见到了良好的油气显示,表明苏北盆地具备了泥页岩油气成藏的地质条件。通过对苏北盆地上白垩统—第三系基本石油地质条件分析,指出苏北盆地的金湖凹陷、高邮凹陷、海安凹陷和盐城凹陷的深凹带是泥页岩油气勘探、开发的有利区带。     

Importance of active tectonics during karst formation. A Middle Eocene to Pleistocene example of the Lina Moutains (Irian Jaya,Indonesia)

Abstract

The Lina Moutains show a typical example of karst formation associated to recent and active tectonics. The limestone samples were collected from giant potholes present beneath the heavy rainforest, during speleological expeditions to the Bird’s Head of Irian-Jaya. Micropalaeontological data allow us to give a Middle Pleistocene age for the most recent karst formation. A detailed stratigraphy between the Upper Lutetian and the Middle Pleistocene was recorded, with tectonic events during the Oligocene and Pleistocene. The edge of the resurgence layer was also dated. We also conclude the probable existence of a subterraneous network downhill of the karst within the most recent levels of the Kais Limestone formation. We replace this formation within the tectonic evolution of this area between the Eocene and the Middle Pleistocene, in conjunction with the oblique convergence of the Pacific plate carrying volcanic arc fragments and the Australian margin, which resulted in folding, normal faulting associated with local extension, and wrench motion, which are settings capable of creating uplift of the carbonated platform. © Elsevier, Paris     

甘肃北山地区北部上石炭统火山岩LA—ICP—MS锆石U—Pb年龄及其构造意义

北山地区处于华北板块、塔里木板块和哈萨克斯坦板块的交会带,其晚古生代洋陆转化备受关注,但久有争议。该区晚古生代地层学研究不足,制约了对构造演化的深入讨论。通过LA—ICP—MS锆石U—Pb测年获得北山北部黑鹰山地区原定为下石炭统白山组火山岩的年龄分别为308．6Ma±1．0Ma和299．1Ma±2．4Ma,时代为晚石炭世。研究区内白山组时代的修订可以为该区构造演化提供一定的依据。     

四川盆地上三叠统须家河组烃源岩埋藏史及热演化特征

根据地层分层数据和古热流分析,运用PetroMod-1D软件对四川盆地的51口探井进行模拟,得到了盆地内上三叠统的埋藏史、成熟度演化史及烃源岩受热史,初步划分了上三叠统烃源岩的成熟阶段和生烃期次。结果表明,川北、川中地区须家河组烃源岩分别在中晚侏罗世进入生烃门限;川南地区大约在早白垩世达到生烃门限,此后地层不断埋深,热演化持续进行,在晚白垩世达到最大埋深,之后由于燕山末期及喜山期构造运动,地层发生整体抬升,干酪根的热演化也因此受到了遏制．     

The Tiger Sulfide Chimney,Yonaguni Knoll IV Hydrothermal Field,Southern Okinawa Trough,Japan: The First Reported Occurrence of Pt–Cu–Fe‐Bearing Bismuthinite and Sn‐Bearing Chalcopyrite in an Active Seafloor Hydrothermal System

A sulfide chimney ore sampled from the flank of the active Tiger vent area in the Yonaguni Knoll IV hydrothermal field, south Okinawa trough, consists of anhydrite, pyrite, sphalerite, galena, chalcopyrite and bismuthinite. Electron microprobe analysis indicates that the chalcopyrite contains up to 2.4 wt% Sn, whereas bismuthinite contains up to 1.7 wt% Pt, 0.8 wt% Cu and 0.5 wt% Fe. The Sn‐rich chalcopyrite and Pt–Cu–Fe‐bearing bismuthinite are the first reported occurrence of such minerals in an active submarine hydrothermal system. The results confirm that Sn enters the chalcopyrite as a solid solution towards stannite by the coupled substitution of Sn⁴⁺Fe²⁺ for Fe³⁺Fe³⁺, whereas Pt, Cu and Fe enter the bismuthinite structure as a solid solution during rapid nucleation. The fluid inclusions homogenization temperatures in anhydrite (220–310°C) and measured end‐member temperature of the vent fluids on‐site (325°C) indicate that Sn‐bearing chalcopyrite and Pt–Cu–Fe‐bearing bismuthinite express the original composition of the minerals that precipitated as metastable phases at a temperature above 300°C. The result observed in this study implies that sulfides in ancient volcanogenic massive sulfide deposits have similar trace element distribution during nucleation but it is remobilised during diagenesis, metamorphism or supergene enrichment processes.     

青藏高原晚白垩世地层区划

对青藏高原晚白垩世地层进行了系统的梳理,开展了青藏高原晚白垩世地层区划的初步研究,共划分出3个地层大区、12个地层区、12个地层分区。详细介绍了各个地层区的上白垩统的地层命名系统及发育情况,其中青藏高原北部祁连-柴达木-巴颜喀拉-羌塘地层大区主要为河湖相沉积的陆相地层系统;青藏高原中部班公湖．双湖．怒江地层大区主要为一套陆相磨拉石沉积地层;青藏高原南部冈底斯一喜马拉雅地层大区主要以海相地层、海陆过渡相地层为主。     

Hydrocarbon potential of the Zechstein Main Dolomite in the western part of the Wielkopolska platform,SW Poland: New sedimentological and geochemical data

The results of identification of facies and microfacies of highstand systems tract (HST) deposits in the Zechstein Main Dolomite (Ca2) are presented followed by a critical analysis of the existing views on the paleogeography and facies architecture of the Wielkopolska Platform (eastern part of the Fore-Sudetic Monocline, SW Poland). The authors discuss and question, the existence in zones that have been treated as basinal flat in the analysed area, and an extensive platform margin ooidal barrier. In general, the facies architecture of the study area resembles the block built of the Paleozoic basement.On this background analytical geochemical results are presented and their source nature characterized in the context of a new revised model of the Ca2 basin paleogeography. A new facies classification of carbonates, which has not been applied for the Polish part of the Ca2 basin yet, was presented. The geochemical characteristic of Ca2 rocks indicates that good oil-prone source rocks are present only locally and are connected with calcisiltites and dolomudstones of facies II and dolobindstones of facies IV. These facies are mainly present in the slope and toe-of-slope zones. The microbial-algal facies, abundant in the carbonate platform, have a weaker residual potential. However, the thermal maturity stays within the entire range of the “oil window”, the rocks should be re-labeled as good source rocks. The presence of oil-prone kerogen Type II, and locally even Type I, makes the Ca2 beds in this part of the Wielkopolska Platform a very efficient source rock, the character of which is confirmed by numerous hydrocarbon accumulations, related to the course of tectonic zones and morphology of the basement. The proposed characteristic of source rocks in the new paleogeographic-facies system, enables their better petroleum evaluation and shall enable future prospecting of the perspective zones.     

高空槽强度指数的构建及其定量化研究

利用2002~2010年25°N~35°N,110°E~120°E范围内的NCEP 1°×1°500 hPa高度场、涡度场和风场6 h再分析资料,运用层次分析法,构建出高空槽强度指数TSI。结果表明,TSI的大小与槽强度有很好的一致性,即TSI越大槽越强。TSI不仅对槽有较好的指示意义,对脊也有一定的指示意义。其中当TSI0.6时,高空槽在该区域较明显;0.35≤TSI≤0.6时,槽脊都不明显,即主要表现为一致的西风环流;TSI0.35时,高空脊较为明显。利用2011年的数据对该指数进行检验,检验效果较好。另外,定量分析较强高空槽(TSI≥0.6)的月分布规律发现,较强槽冬季较多而夏季较少。