泥石流平面形态的统计分析

泥石流扇的平面形态可用规划的几何图形来模拟。在研究了中国西南地区小江流域和意大利东北部阿尔卑斯山区的５２个泥石流扇的基础上，本文提出了两种泥石流扇的平面形态：中国西南地区的“等腰三角形＋半圆形”泥石流扇和意大利东北部的“几何扇”。用统计分析建立了两组泥石流扇和泥石流流域之间的形态度量关系。通过两个研究区域的对比，两个流域参数：流域面积和主沟比降确定为影响泥石流扇平面形态和面积的最重要的因素。     

试论东海陆架盆地的基底构造演化和盆地形成机制

本文主要根据东海陆架盆地和周边的地质、地球物理资料,分析盆地的基底岩性特征、结构特征。认为东海陆架盆地的基底除元古界片麻岩外,还分布有一定范围的中生界及古生界。基底构造特征是纵向上多层次,横向上不均一,南北有别,东西分带。构造演化上经历了张、合、压、扭等复杂过程。     

海洋沉积地质过程模拟:性质与问题及前景

探讨了海洋沉积地质数值模拟的功能问题.地球科学研究以正演方法(以数值模拟为代表)和反演方法(以地层记录分析为代表)的结合为特征.数值模拟作为一种重要的研究工具,具有获得过程和机理分析结果、形成工作假说、指导现场观测和采样的作用.与此同时,在正反演交融中模型本身也得到了提高和完善.在海洋沉积地质领域,数值模拟在沉积物输运...     

Modelling the wave-current interactions in an offshore basin using the SWAN model

The theoretical background of the wave-current interactions, including the transformation of the wave spectrum and breaking waves due to currents, are first presented in this work. In the next part of the work, experimental data resulted from studies performed in an offshore wave basin of the Danish Hydraulic Institute concerning the wave-current interactions were presented in parallel with some wave model simulations performed in similar conditions. SWAN, which is presently the state-of-the-art spectral model for the wave transformations, was adopted for performing numerical simulations. In general, a good agreement was encountered between the experimental data and the simulation results.     

In-situ stress state in the Linxing region,eastern Ordos Basin,China: Implications for unconventional gas exploration and production

The Carboniferous and Permian sedimentary rocks (mainly the Shanxi and Taiyuan formations) in the Linxing region, eastern Ordos Basin, China, host a significant volume of unconventional gas resources (coalbed methane, shale gas and tight sandstone gas). Currently, the in-situ stress state is poorly understood but knowledge of this is extremely important for a range of applications, such as gas exploration and production, fracture stimulation and wellbore stability. The maximum horizontal stress (S_Hmax), minimum horizontal stress (S_hmin) and vertical stress (S_v) magnitudes, and the S_Hmax orientation in the Linxing region were systematically analyzed for the first time in the present study, which can provide a reference for subsequent numerical simulation and hydraulic fracturing design. Based on borehole breakouts and drilling-induced tensile fractures interpreted from borehole imaging logs, the S_Hmax orientation rotates from ∼NEE-SWW-trending in the southern part to ∼ NWW-SEE-trending in the northern part of the Linxing region. Both conventional logs and extended leak-off tests were used for stress magnitude determination. The results revealed three types of in-situ stress fields (S_v > S_Hmax > S_hmin, S_Hmax > S_v > S_hmin and S_Hmax > S_v ≈ S_hmin), and a dominant strike-slip stress regime (S_Hmax > S_v ≥ S_hmin) was found for the entire well section in the target Shanxi Formation and Taiyuan Formation in the Linxing region. In addition, differential stress increased with depth in the Linxing region, which indicates that wellbore instability might be a potentially significant problem when drilling wells that are vertical or ∼ N-S-trending.     

山地冰川演化与冰湖发育相互作用机制北大核心CSCD

冰川-冰湖耦合过程是冰冻圈物质与能量循环的重要组成部分,系统刻画冰川演化与冰湖发育过程的相互作用机制,对于完善冰冻圈科学理论体系和认知冰川作用区变化规律、水循环模式和灾害效应具有重要意义。本文立足山地冰川演化和冰湖发育过程,系统归纳了冰川-冰湖相互作用研究进展,剖析了冰川作用与冰湖发育耦合机制及相关模型的应用,并对现有冰川演化与冰湖发育过程耦合机制研究存在的不足与挑战进行解析和总结。冰川-冰湖耦合过程的深入研究有助于提高数值模拟的可信度与精度,为评估冰川-冰湖耦合过程影响、建立灾害监测预警体系和采取适应性措施提供数据与理论基础。     

河北省物理地层界线厘定

以现代地层学多重划分为理论依据,以岩石地层单元组的密度、磁化率、剩余磁化强度及厚度加权算术平均值等物性参数为研究对象,以有序地质量最优分割方法为数学手段,进行河北省全区综合地层柱物理地层界线的厘定,并对其地质意义进行了初步讨论。     

南黄海盆地古潜山分类及构造特征

南黄海是下扬子的主体,奠基于晋宁期变质基底之上,构造演化历经南华纪—早、中三叠世海相地层发育期、晚白垩世—古近纪箕状断陷发育期和新近纪—第四纪坳陷发育期,为一典型地台-断陷-坳陷多层结构的复合盆地。盆地历经多次构造运动改造,古潜山发育,类型多样。在总结前人对古潜山研究的基础上,结合南黄海新近采集的二维地震剖面,对该地区古潜山类型进行了系统划分,并对典型古潜山的构造特征及生储盖匹配关系进行了初步描述。根据成因划分为剥蚀型潜山、拉张型潜山、挤压型潜山和复合型潜山四大类,每一类又可根据形态划分出剥蚀残丘型潜山、拉张翘倾断块型潜山、拉张断阶型潜山、拉张断垒型潜山、挤压褶皱型潜山、拱张褶皱型潜山和褶皱—断块复合型潜山等类型。南黄海盆地古潜山的发育具有分带性,按盆地中潜山的构造位置,分为凸起潜山带、陡坡潜山带、洼陷潜山带和缓坡潜山带,每一构造带发育了不同类型潜山。研究表明南黄海古生界和中生界古潜山数量众多,规模较大,是南黄海地区实现油气突破的一种重要油气藏类型。     

西太平洋富钴结壳超微化石与分子化石地层划分及对比

对具典型三层构造的西太平洋海山群富钴结壳样品进行了钙质超微化石地层学研究,获取了富钴结壳从内层致密层、中间疏松层到外层较致密层的生长时代:CM1D03为晚古新世-早始新世、始新世中期、中中新世-更新世;CM3D06分为晚古新世-早始新世、中始新世-晚中新世、上新世-更新世。对富钴结壳壳层的甾烷系列分子(C27、C28、C29)进行了检测并计算了相对含量,结果表明,两块富钴结壳的甾烷分布构型在结壳生长时代上具有一致性:晚古新世-早始新世,呈反"L"型分布;中始新世呈C27优势的"V"型分布;中新世-更新世呈C29优势的"V"型分布。甾烷分布构型的变化与古海洋环境演化造成的海底甾烷输入波动有关,具有一定的时代特征钙质超微化石和分子化石地层学划分方法在富钴结壳层主要生长时代及生长间断的界定上具有一致性,可以用于富钴结壳的地层划分和对比。     

3D architecture of Quaternary sediment along the NW Atlantic Moroccan Rharb continental shelf: A stratal pattern under the dual control of tectonics and climatic variations

This study focuses on the evolution of the Atlantic NW Moroccan Rharb continental shelf during the Neogene and Quaternary. This region is part of a foreland basin bounded by the Rif mountain belt and thus provides an interesting geological setting to study the interactions between eustasy and tectonics and the driving mechanisms controlling stratigraphic patterns. The results are supported by an interpretation of new data including high-resolution seismic lines coupled with an interpretation of industrial seismic lines and detailed logs of industrial wells completed by micropaleontologic analysis of cuttings. The stratigraphy reveals a succession of three mega sequences related to the transition from an underfilled to an overfilled stage reflecting the long-term evolution of the foreland system. Moreover, evidence of cyclical sea-level changes are visible in the upper megasequence composed of three depositional sequences assumed to be fourth-order sequences generated in response to the most recent 100-ka glacio–eustatic cycles. This study also shows the peripheral deformation of the Rharb shelf responsible for changes in the geometry of the deposits and thicknesses of the sedimentary fill during the Pliocene and Pleistocene. The most important change was triggered by the uplift of the Lallah Zahra Ridge corresponding to a major Quaternary kinematic boundary and the broad uplift of the southern shelf interpreted as a flexural uplift of the forebulge domain. The deformation-controlled sediment dispersal pattern consists of a progressive growth of the shelf accompanied with a progressive shift of depocenters from the North East to the South West and a general progradation to the North West along the southern border. This progressive filling has led to the confinement of the Rharb paleo-valley across the continental shelf. The complete filling of the palaeo-valley was followed by the development of a more than 70-m thick prodeltaic lobe at the front of the Oued Sebou river mouth during the Holocene.