孟加拉湾晚第四纪的碳酸盐溶解旋回     

丁旋  郝诒纯  万晓樵  方念乔 《沉积学报》2001,19(2):192-198

孟加拉湾由于陆源物质大量输入产生稀释效应,使碳酸盐含量表现为冰期时减小、间冰期时增大的“大西洋型”旋回。通过对该区四支活塞岩芯的有孔虫溶解指数、浮游有孔虫沉积通量、CaCO₃ 沉积通量和 >16 0 μm粗组分沉积通量的分析发现,研究区碳酸盐溶解作用强烈,表现出冰期减弱而间冰期增强的总趋势,且溶解作用滞后于浮游有孔虫壳的氧同位素旋回,尤以氧同位素 4、5期的高溶解度情况与印度洋和太平洋氧同位素 5期晚期至 4期为CaCO₃溶解高峰一致。因此,孟加拉湾地区的CaCO₃ 旋回是大西洋型稀释作用与太平洋型溶解作用两者叠加的产物.  相似文献   

碳酸盐岩红土风化壳主要特征及红土成因探讨—以贵州典型剖面为例   总被引：12，自引：0，他引：12  

李景阳  朱立军  梁风 《水文地质工程地质》2001,28(5):7-11,16

本文总结提出了碳酸盐岩风化壳成因证据及其演化特点，对风化壳红土成因进行了讨论。  相似文献   

滨海岩溶区过渡带碳酸盐岩溶浊作用的试验研究   总被引：3，自引：0，他引：3  

邹胜章  陈鸿汉  朱远峰  刘菲 《水文地质工程地质》2001,28(5):17-20

滨海岩溶具有内陆一般岩溶区不同的发育机理，其过渡带混合溶蚀作用是控制滨海岩溶发育的最主要因素之一。通过七组不同淡水与海水配比的混合溶蚀实验（封闭CO2－H2O系统），初步得出了过渡带混合溶蚀作用的基本结论：（1）滨海岩溶区过渡带岩溶发育的基本规律与内陆一般岩溶区岩溶发育规律的基本一致，即岩性，结构是控制滨海岩溶发育的最主要因素；（2）滨海岩溶区混合过渡带内碳酸盐岩的混合溶蚀速率大于纯淡水或纯海水中同种岩石的溶蚀速率；（3）在不同的CO2分压条件下，滨海岩溶区混合过渡带内碳酸盐岩的混合溶蚀机理不同。  相似文献   

重质碳酸钙表面改性及充填丁苯橡胶试验研究     

杨眉  沈上越  蒋鹏 《矿物岩石》2001,21(4):19-22

重质碳酸钙是一种重要的无机矿物填料，经过表面改性，可以将其由普通填料变成性能优越的功能填料。本次研究选用鄂西优质重质碳酸钙为试验样品，采用干法表面化学改性方法对重质碳酸钙实施了改性，通过测定改性重质碳酸钙的活化率、湿润接触角、固液悬浮体的粘度、白度及表面化学成分对其性能进行考察，并对改性效果进行评价。在丁苯橡胶中的应用试验显示，改性重质碳酸钙充填丁苯橡胶的性能良好，其应用前景广阔。  相似文献   

川东地区碳酸盐岩超压与天然气富集关系研究   总被引：7，自引：2，他引：7  

李仲东 《矿物岩石》2001,21(4):53-58

地层流体超压的形成、演化及分布与油气成藏的主要石油地质过程有着千丝万缕地联系。由于碳酸盐岩本身的复杂性，其超压的成因及研究方法不能简单地借用“欠压实”的原理。本文从对比砂泥岩和碳酸盐岩在成压机理上的差异性入手，详细探讨了川东地区碳酸盐岩成压的各种机理，指出成烃作用是造成区域性超压的最主要因素；并结合该区超压平面上的分区性及纵向上的分带性，论述了各区、带超压与气藏分布的内在联系，总结出该区超压与天然气富集的关系。  相似文献   

Crack-filling clays and weathered cracks in the DPRI 1800 m core near the Nojima Fault, Japan: Evidence for deep surface-water circulation near an active fault     

Shin-Ichi Uda  Aiming Lin  Keiji Takemura 《Island Arc》2001,10(3-4):439-446

Abstract Crack-filling clays and weathered cracks were observed in the Disaster Prevention Research Institute, Kyoto University (DPRI) 1800 m cores drilled from the Nojima Fault Zone, which was activated during the 1995 Hyogo-ken Nanbu earthquake (Kobe earthquake). The crack-filling clays consist mainly of unconsolidated fine-grained materials that fill opening cracks with no shear textures. Most of the cracks observed in the DPRI 1800 m cores are yellow-brown to brown in color due to weathering. Powder X-ray diffraction analyses show that the crack-filling clays are composed mainly of clay minerals and carbonates such as siderite and calcite. Given that the top of the borehole is approximately 45 m above sea level, most of the core is far below the stable groundwater table. Hence, it is suggested that the crack-filling clays and weathered cracks in the cores taken at depths of 1800 m were formed by the flow of surface water down to the deep fractured zone of the Nojima Fault Zone during seismic faulting.  相似文献   

Storm deposits and storm-generated coarse carbonate breccias on a pelagic outer shelf (South-East Basin, France)   总被引：2，自引：0，他引：2  

Michel Seguret  Alexis Moussine-Pouchkine  Guilherme Raja Gabaglia  & Frederic Bouchette 《Sedimentology》2001,48(2):231-254

Uppermost Jurassic limestones of the South‐East Basin (France) are organized into four facies associations that were deposited in four distinct zones: (1) peritidal lagoonal limestones; (2) bioclastic and reefal limestones; (3) pelagic lime mudstones; (4) lime mudstones/calcarenites/coarse breccias. Calcarenite deposits of zone 4 exhibit sedimentary structures that are diagnostic of deposition under wave‐induced combined flow. In subzone 4a, both vertical and lateral transitions from lime mudstone/calcarenite to breccia indicate in situ brecciation under wave‐cyclic loading. Breccias were produced by heterogeneous liquefaction of material previously deposited on the sea floor. Deposits in subzone 4a record relatively long periods (>400 kyr) of sedimentation below wave base, alternating with periods of deposition under wave‐induced currents and periods of in situ deformation. In this zone, storm waves were attenuated by wave–sediment interaction, and wave energy was absorbed by the deformation of soft sediment. With reference to present‐day wave attenuation, water depths in this zone ranged between 50 and 80 m. Landwards of the attenuation zone, in zone 3, storm waves were reduced to fair‐weather wave heights. Storm wave base was not horizontal and became shallower landwards. As a consequence, water depth and wave energy were not linearly related. On a small area of the seaward edge of subzone 4a, cobbles were removed by traction currents and redeposited in subzone 4b. There, they formed a 100‐m‐thick wedge, which prograded over 3 km and was built up by the stacking of 5‐ to 20‐m‐thick cross‐stratified sets of coarse breccia. This wedge records the transport and redeposition of cobbles by a high‐velocity unidirectional component of a combined flow. The increase in flow velocity in a restricted area is proposed to result from flow concentration in a channel‐like structure of the downwelling in the gulf formed by the basin. In more distal subzone 4c, the hydrodynamic effect of wave‐induced currents was quasi‐permanent, and brecciation by wave–sediment interaction occurred only episodically. This indicates that, seawards of the attenuation zone, hydrodynamic storm wave base was deeper than mechanical storm wave base. Uppermost Jurassic carbonates were deposited and soft‐sediment deformed on a hurricane‐dominated ramp of very gentle slope and characterized by a zone of storm wave degeneration, located seawards of a zone of sedimentation below wave base.  相似文献   

Long-distance correlation between tectonic-controlled, isolated carbonate platforms by cyclostratigraphy and sequence stratigraphy in the Devonian of South China   总被引：5，自引：1，他引：5  

Daizhao Chen  Maurice E. Tucker  Maosheng Jiang  & Jingquan Zhu 《Sedimentology》2001,48(1):57-78

During the early Middle Devonian in South China, an extensive carbonate platform was broken up through extension to create a complex pattern of platforms, and interplatform basins. In Givetian and Frasnian carbonate successions, five depositional facies, including peritidal, restricted shallow subtidal, semi‐restricted subtidal, intermediate subtidal and deep subtidal facies, and 18 lithofacies units are recognized from measured sections on three isolated platforms. These deposits are arranged into metre‐scale, upward‐shallowing peritidal and subtidal cycles. Nine third‐order sequences are identified from changes in cycle stacking patterns, vertical facies changes and the stratigraphic distribution of subaerial exposure indicators. These sequences mostly consist of a lower transgressive part and an upper regressive part. Transgressive packages are dominated by thicker‐than‐average subtidal cycles, and regressive packages by thinner‐than‐average peritidal cycles. Sequence boundaries are transitional zones composed of stacked, high‐frequency, thinner‐than‐average cycles with upward‐increasing intensity of subaerial exposure, rather than individual, laterally traceable surfaces. These sequences can be further grouped into catch‐up and keep‐up sequence sets from the long‐term (second‐order) changes in accommodation and vertical facies changes. Catch‐up sequences are characterized by relatively thick cycle packages with a high percentage of intermediate to shallow subtidal facies, and even deep subtidal facies locally within some individual sequences, recording long‐term accommodation gain. Keep‐up sequences are characterized by relatively thin cycle packages with a high percentage of peritidal facies within sequences, recording long‐term accommodation loss. Correlation of long‐term accommodation changes expressed by Fischer plots reveals that during the late Givetian to early Frasnian increased accommodation loss on platforms coincided with increased accommodation gain in interplatform basins. This suggests that movement on faults resulted in the relative uplift of platforms and subsidence of interplatform basins. In the early Frasnian, extensive siliceous deposits in most interplatform basins and megabreccias at basin margins correspond to exposure disconformities on platforms.  相似文献   

Cyclic strength and deformation of crushable carbonate sand     

Masayuki Hyodo  Noritaka Aramaki  Masayuki Itoh  Adrian F.L. Hyde 《Soil Dynamics and Earthquake Engineering》1996,15(5):331-336

Cyclic triaxial tests have been carried out on a skeletal carbonate sand from the west coast of Eire. Results are presented for undrained cyclic shear tests on samples with 80% of relative density consolidated under both isotropic and anisotropic conditions. Failure was defined as a 5% double amplitude cyclic strain and a 5% peak axial strain for stress-reversal and non-reversal stress conditions, respectively. Using this definition the cyclic strength for isotropically consolidated samples was affected by the confining pressure although the angular platey nature of the sand resulted in higher cyclic strengths than for a comparable silica sand. For anisotropically consolidated samples the cyclic strength increased with increasing initial static shear stress while on the other hand the cyclic strength normalised in the usual way with respect to the initial confining pressure decreased as this pressure increased.  相似文献   

碳酸盐矿物的阴极发光性与其Fe,Mn含量的关系   总被引：40，自引：2，他引：40  

黄思静 《矿物岩石》1992,12(4):74-79

根据不同地区和时代84件碳酸盐样品的阴极发光和Fe,Mn元素分析,在本次研究使用的仪器和实验条件下,方解石和白云石的阴极发光性与其Fe,Mn含量之间存在如下关系:Mn<40μg/g(ppm)时,其阴极发光性主要受Mn的绝对含量控制,当Mn<20μg/g时,不具阴极发光;Fe>5000μg/g时,其阴极发光性与Fe的绝对含关系更为密切,当Fe>10000μg/g时,不具阴极发光;Mn>40μg/g,Fe<5000μg/g时,其阴极发光性受Fe/Mn比值的显著控制,此时当Fe/Mn<7时,具强的阴极发光,30>Fe/Mn>7时,具中等强度的阴极发光,Fe/Mn>30时,具弱的阴极发光。两个热液碳酸岩中单晶白云石样品的阴极发光性和稀土元素含量间的关系说明,碳酸盐矿物的阴极发光性可能还与某些稀土元素的存在有关,它们可能是某些样品具低激活电压和长发光余辉的原因。  相似文献