娄底地区环境地质灾害问题初探     

周治国 《湖南地质》1993,12(1):47-50

娄底地区环境地质灾害较严重。主要有地震、地裂、塌陷、滑坡、水土流失和水污染等。这些灾害的形成除受天然状态下的第一地质环境影响外,主要与第二环境即开矿、建厂、修路及兴修水和等人类活动有关。针对各类灾害及其危害性,提出了防治对策与建议。  相似文献   

海南岛红树林泥炭中硫及其成因研究   总被引：4，自引：2，他引：4  

桑树勋  刘焕杰 《煤田地质与勘探》1993,21(1):12-17

海南岛红树林泥炭普遍富硫。黄铁矿、硫酸盐和有机硫是泥炭中硫的三种主要赋存形态,其中,以黄铁矿硫高为特征。利用形态硫分析、硫同位素分析等手段结合硫的时空变化特征,研究了泥炭中硫的形成机理。泥炭中硫的富集与泥炭坪环境具紧密的成因联系,全硫和形态硫的时空变化受微环境的控制;潮坪水介质中的硫酸盐是泥炭中硫的最初来源;泥炭中硫的加入,主要发生于准同生价段,在加入过程中还原硫细菌起了决定性作用。定量沉积环境分析是查明古代富硫煤田硫分布的主要途径。  相似文献   

镇江市运河滑坡机理分析     

梁敬方  唐末林 《上海国土资源》1993,(4):19-25

镇江市古运河边岸滑坡干扰了城市交通、航运和河道整治工程的正常运行。本文研究了城市边岸的工程环境、滑坡形态、特有的城市地质环境恶化所诱发的边岸破坏机制及其稳定性,它对我同城市水陆交通发展所导致的斜坡地质灾害及其治理有实用价值。  相似文献   

包气带黄土环境研究与放射性废物处置     

许兆义  赵英杰 《水文地质工程地质》1993,20(5):42-46

黄土中的粘粒含量较高、比表面积较大、吸附性较强、阳离子交换容量也较高,这些因素对迟滞放射性核素的迁移有利。而且黄土的非饱和渗透系数K(θ)远远低于它的饱水渗透系数K_(?)。使得放射性核素在黄土中的迁移很慢。因此,包气带黄土作为中、低放射性废物处置库的环境屏障是可行的。  相似文献   

能源基地晋陕蒙接壤地区地质环境质量定量研究     

何荣文 《陕西地质》1993,(2)

本文基于地质环境是由诸多因素有机组合而成,其质量也是各因素质量的复杂组合,是一种模糊现象,难以精确评价,但又存在明显差异的认识,采用模糊数学理论,即以环境地质亚区为单元,考虑多因素的综合影响。采用数量化的动态聚类法,对晋陕蒙接壤地区地质环境质量进行了评价:包括自然条件下地质环境质量评价和煤炭、水资源开发后地质环境质量的相对变化评价。  相似文献   

关于火山岩型铀矿床成矿规律中一些问题的讨论   总被引：5，自引：2，他引：5  

俞时清  邸瑞姞 《铀矿地质》1993,(2)

火山岩型铀矿常位于大的地质构造单元界线附近,特别是稳定区与活动区之间的过渡带上。矿区的基底不仅需有较高的成熟度而且是在火山岩形成前或长期处于隆起状态者。负向火山构造,上叠式或拗凸型上叠式火盆是铀矿田的有利构造形式。红盆对成矿的作用不是古气候方面的而是构造方面的。火山岩型铀矿成矿深度可以较大,而且在垂向上不只一个富集高峰。铀及其主要伴生组份不是来源于赋矿围岩,而是来自基底或更深处。  相似文献   

New radiolarian ages from the Troodos ophiolite and their tectonic implications   总被引：3，自引：0，他引：3  

Soichi  Osozawa Makoto  Okamura 《Island Arc》1993,2(1):1-6

Abstract Newly obtained radiolarian biostratigraphic age combined with previous isotopic age of the Troodos ophiolite shows that the ophiolite becomes systematically younger from east to west: Turonian, early Campanian, and late Campanian. The youngest late Campanian part of the ophiolite is directly covered by the volcaniclastic sediment derived from an active island arc, whereas the older part is covered by pelagic radiolarite. These facts constitute evidence that the Troodos ophiolite was probably emplaced during the subduction of an active spreading ridge.  相似文献   

Differences between Mean Sea Levels for the Pacific,Atlantic and Indian Oceans From Topex/Poseidon Altimetry     

Burša  Milan  Kouba  Jan  Müller  Achim  Raděj  Karel  True  Scott A.  Vatrt  Viliam  Vojtíšková  Marie 《Studia Geophysica et Geodaetica》1999,43(1):1-6

Geopotential values W of the mean equipotential surfaces representing the mean ocean topography were computed on the basis of four years (1993 - 1996) TOPEX/POSEIDON altimeter data: W = 62 636 854.10m ² s ^–2 for the Pacific (P), W = 62 636 858.20m ² s ^–2 for the Atlantic (A), W = 62 636 856.28m ²s^–2 for the Indian (I) Oceans. The corresponding mean separations between the ocean levels were obtained as follows: A – P = – 42 cm, I– P = – 22 cm, I – A = 20 cm, the rms errors came out at about 0.3 cm. No sea surface topography model was used in the solution.  相似文献   

Englacial vs lacustrine origin of volcanic table mountains: evidence from iceland     

Reinhard Werner  Hans-Ulrich Schmincke 《Bulletin of Volcanology》1999,60(5):335-354

Detailed facies analysis of hyaloclastites and associated lavas from eight table mountains and similar "hyaloclastite volcanoes" in the Icelandic rift zone contradict a rapid and continuous, "monogenetic", entirely subglacial evolution of most volcanoes studied. The majority of the exposed hyaloclastite deposits formed in large, stable lakes as indicated by widespread, up to 300-m-thick, continuous sections of deep water, shallow water and emergent facies. Salient features include extensively layered or bedded successions comprising mainly debris flow deposits, turbidites, base surge and fallout deposits consisting of texturally and compositionally variable, slightly altered hyaloclastites, as well as sheet and pillow lavas. In contrast, chaotic assemblages of coarser-grained, more poorly sorted and more strongly palagonitized hyaloclastite tuffs and breccias, as well as scoria and lava are interpreted to have formed under sub- or englacial conditions in small, chimney-like ice cavities or ice-bound lakes. Irregularly shaped and erratically arranged hyaloclastite bodies produced at variable water levels appear to have resulted mainly from rapid changes of the eruptive environment due to repeated build-up and drainage of ice-bound lakes as well as the restricted space between the ice walls. We distinguish a "deep water" facies formed during high water levels of the lake, a hydroclastic shallow water and emergent facies (leakage of the lake or growth of the volcano above the water surface). Our model implies the temporary existence of large, stable lakes in Iceland probably formed by climatically induced ice melting. The highly complex edifices of many table mountains and similar volcanoes were constructed during several eruptive periods in changing environments characterized by contrasting volcanic and sedimentary processes. Received: 10 June 1997 / Accepted: 28 July 1998  相似文献   

卡尼期湿润幕：气候- 环境变化与海洋生态效应研究新进展     

曾建理  张廷山  杨巍  马知恒  李世鑫  张喜 《地质学报》2022,96(3):729-743

晚三叠世卡尼期湿润幕（Carnian Pluvial Episode, CPE）是近年来最受瞩目的地质事件之一。此次事件以卡尼中期全球不同纬度环境湿度显著上升为主要标志。CPE的发生不仅对全球各地沉积格局产生重大改变，也对三叠纪生物演化产生了深远影响。海洋生物群在跨越CPE期间发生了不同程度的灭绝与演替，大部分海洋无脊椎动物和部分脊椎动物的多样性在CPE之后出现明显的降低，著名的关岭生物群也受到了CPE的明显影响，并开始显现出危机。CPE之后，恐龙类群开始逐步占据陆地生态的主导地位，早中生代和现代生物的先祖开始在这一时期纷纷出现。CPE的发生揭开了现生生物演化史新的一页，并最终开创了早中生代和现生生物黎明。有关CPE的触发机制主要包括以下2个方面：① 晚三叠世巨型季风环流在卡尼期达到鼎盛并区域上影响了大气降水量；② 板块活动造成大规模火山喷发引发全球气候扰动。由于上述2种解释还未能与我国其他地质记录较好匹配，因而CPE在特提斯东缘的发生次序和发展过程并不清晰。这其中，对CPE触发机制的探讨，需要将全球板块变化与古气候模拟纳入其研究范畴。不同于晚二叠世生物大灭绝后生物类群缓慢重启和生态逐步复苏，CPE期间的生物演化与革新在短时间内促成了现代生物类群的形成。在我国，上三叠统卡尼阶分布广泛、发育齐全，且保存有各门类丰富的动植物化石，是开展卡尼期气候- 环境变化与生态效应研究的重要场所。然而目前国内有关CPE研究还十分有限，一些基础的地质工作仍然有待开展。位于特提斯东缘的我国地质记录有助于深刻理解CPE过程和环境- 生物协同演化关系，尤其在现代生物多样性起源和当代生态系统结构成型的研究过程中需要提供更多中国的对比方案。  相似文献