Sediment texture and grain-size implications: the Changjiang subaqueous delta

Sediment cores were collected from the subaqueous delta of the Changjiang Estuary. Sediment grain-size profiles and their fractal dimensions were analyzed, to elucidate responses to long-term sedimentary processes. In addition, the environmental sensitive populations of grain size have been extracted. The sediment cores can be divided into two parts, according to the sedimentary structures present. The upper part (0-12 cm) is interpreted as being the active layer, which is influenced frequently by changes i...     

Late Paleozoic tectonic evolution in northern Korean Peninsula

Since Late Proterozoic era, the Korean Peninsula has been evolved into a state with relatively stable regions and orogenic belts which were developed differently each other. The Late Paleozoie （Late Carboniferous-Early Triassic） sediments are well developed in the Korean Peninsula, and called the Pyongan System. The Pyongan System from Late Carboniferous to Lower Triassic is distributed in the Pyongnan and Hyesan-Riwon Basins, and Rangrim Massif, and divided into Hongjom （ C2 ）, Ripsok （ C2 ）, Sadong （ C2-P1 ）, Kobangsan and Rokam （Taezhawon） （P2-T1） sequences. The sediments of the Tumangang Orogenic Belt are called Tuman System which is composed of the Amgi Series, consisting of elastic formation with mafic effusive material, overlaid by the Kyeryongsan Series, consisting mainly of marie volcano sediments. The Songsang Series which rests on the Kyeryongsan Series mainly consists of elastic formation with minor felsic effusive material. In the Tumangang Orogenic Belt the tectonic movement, called Tumangang Tectonic Movement, occurred in the Lower Permian-Lower Triassic.     

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.     

区域矿产资源规划基础理论研究

区域成矿学是研究特定区域中的成矿环境、成矿条件、成矿过程、成矿类型及成矿演化的一门学科,是进行区域矿产预测、普查找矿和资源潜力评价的理论基础。     

惠民凹陷孔店期盆地原型格架对油气成藏的影响

为了准确评价惠民凹陷古近系孔店组的油气资源,研究盆地原型格架对油气成藏的影响是一个重要的方面.首先对盆地的构造演化进行分析,发现受构造演化的影响,孔店组不同时期的厚度(或残留厚度)在凹陷不同部位有所不同,导致主力烃源岩生烃条件发生变化;孔店期原型盆地为北断南超的伸展半地堑,盆地长轴方向整体为近东西向,主要的控制性断层是凹陷北部的边界断层-滋镇断层和阳信断层;通过计算盆地的残余厚度和剥蚀厚度,恢复了原型盆地的厚度,孔二亚段地层向南部斜坡带超覆,发育3个沉降中心,分别位于滋镇和临南洼陷东北部及阳信洼陷,孔一亚段沉积具有继承性,但北东向的滋镇、阳信断层对地层的控制更为明显;沉积中心迁移的结果显示:孔二亚期-孔一亚期沉积中心迁移,对在滋镇和临南洼陷内孔店组地层油气成藏及阳信断层下降盘的储层中成藏有利,但孔一亚期-沙四亚期沉积中心的迁移,对油气在孔一-沙四段储层中成藏不利.     

福建泉州市区域稳定性的探讨

本文对泉州市区域地壳结构、地质构造、构造应力场和地震活动性进行了综合分析.结果表明,泉州市在第四纪中更新世之前位于环太平洋中、新生代构造-岩浆活动带中,地壳运动频繁而又强烈,地质构造复杂;现代处于菲律宾海板块对欧亚板块挤压形成的"台湾动力触角"影响区,但区内的断裂不具全新世活动性,新构造运动不强烈,有史以来未见≥5.0级地震记载,属于地壳相对稳定区,未来遭遇6.0级地震的危险性不大,其地震破坏性影响主要来自周边孕震区,特别是东部海域,与"台湾动力触角"的作用和滨海断裂带的活动有关.     

青藏高原东北缘龙首山晚新生代多阶段构造隆升的盆地记录

龙首山地区位于青藏高原与阿拉善地块的结合部位,其盆山演化过程和断裂带扩展模式的恢复对揭示青藏高原新生代北东向生长具有重要意义。本文基于龙首山南北两麓3个新近系沉积剖面的构造特征和5个砂岩样品的碎屑锆石U-Pb同位素LA-ICP-MS年龄结果,重建了青藏高原东北缘龙首山地区晚新生代的盆山演化过程。研究结果显示,龙首山地区晚新生代沉积-构造演化经历了3个主要阶段：（1）~14Ma,龙首山南缘断裂带活化,阿拉善地块南缘沿此断裂逆冲于张掖盆地之上,张掖盆地开始接收阿拉善地块的物源;（2）~5Ma,龙首山南缘断裂带的次级断裂开始发育,使龙首山南侧山麓白垩系开始剥露并为张掖盆地提供物源,同时,龙首山北缘断裂带活化并导致潮水盆地发生挠曲沉降,接收龙首山的物源;（3）5~2.5Ma,龙首山北缘断裂带的次级断裂开始发育,导致龙首山北麓白垩系开始剥露并为潮水盆地提供物源。通过对龙首山周缘盆地沉积相和物源开展分析,本研究反演了龙首山地区中新世以来的断裂带活动和山体隆升过程,表明在14~2.5Ma,随着龙首山南缘断裂、北缘断裂的活化和次级断裂的发育,龙首山经历了3次强烈的隆升,这对揭示青藏高原北东向的扩展过程具有重要的指示意义。

     

某水电站坝前左岸古滑坡成因机制分析

古滑坡坐落于Ⅱ级阶地台面上,堆积物最大厚度可达50m余。利用FLAC^3D数值模拟得到的滑面在前缘位于基覆界面附近,与野外调查的结果一致。结合雅砻江河谷演化历史,从斜坡演化机制、边坡岩体的变形破坏模式,分析了古滑坡成因机制。研究表明：雅砻江快速下切使岸坡岩体浅表改造程度较为剧烈,不断增加的重力堆积静荷载与崩塌形成的瞬时冲击荷载加速了岩体的弯曲一拉裂变形进程,造成Ⅱ级阶地基座岩体发生突发性折断破坏．从而导致古滑坡失稳。     

柴达木盆地东北缘中中新世以来古气候变化

全球变冷、青藏高原隆升以及特提斯洋海退被认为是控制亚洲大陆新生代气候变化的三大因素,然而由于长时间尺度古气候记录的匮乏,对于三者影响的认识并不清晰。柴达木盆地是青藏高原北部最大的一个封闭盆地,发育巨厚且连续的新生代地层,详细记录了周缘山体构造隆升过程和区域气候演化历史。本文通过柴达木盆地东北缘怀头他拉剖面的中中新世-早更新世沉积物气候代用指标碳酸盐、硫酸根和氯离子含量分析,显示该研究区中中新世以来气候变化经历了15.3~13.0Ma相对湿润、13.0~6.6Ma半干旱-半湿润和6.6~1.8Ma干旱的3个演化阶段。结合生物特征和前人研究成果,认为柴达木盆地干旱化历史可能从中中新世13Ma左右开始逐步发展,而真正意义上的干旱化始于6.6Ma以来。全球变冷是控制柴达木盆地干旱气候形成和发展的主导因素,同时青藏高原晚期持续阶段性的强烈隆升起到了催化剂的作用。