贵州碳酸盐岩红土中的粘土矿物及其形成机理

本文运用Ｘ射线衍射、红外光谱、差热、透射电镜和扫描电镜等方法对贵州碳酸盐岩红土中的粘土矿物进行了系统研究。高岭石和０．７ｎｍ埃洛石是碳酸盐岩红土中的主要粘土矿物，其次为伊利石、蛭石、绿泥石、绿泥石／蛭石混层矿物，水铝英石和三水铝石等。     

全谱拟合定量研究气候对土壤成壤机制的约束:以鲁粤土壤剖面为例

以山东棕壤剖面和广东红壤剖面为研究对象,通过X射线衍射(XRD)和基于Rietveld技术的全谱拟合定量分析土壤中的矿物组成、在剖面上的含量变化并研究粘土矿物之间的相互转化关系,揭示气候对土壤成壤机制的约束。结果表明,2个剖面中的矿物组成不同:山东棕壤中非粘土矿物有长石、石英、方解石及少量的铁铝氧化物和闪石类矿物,粘土矿物有伊利石、绿泥石、高岭石和蒙脱石,且粘土矿物含量伊利石>绿泥石≈蒙脱石>高岭石;广东红壤的矿物组成为石英、赤铁矿、针铁矿、三水铝石、高岭石、伊利石和蛭石,其中高岭石>伊利石>蛭石。此外,两地的土壤中均含有少量的非晶质物质。山东气候干冷,以物理风化为主,化学风化较弱,原生闪石类原生硅酸盐矿物和易被溶蚀的方解石等仍有存留;广东气候湿热,化学风化强烈,存在明显的脱硅富铝作用,铁铝氧化物富集。3)利用定量结果计算的化学风化指数与矿物的变化是一致的。     

天津蓟县长城系串岭沟组混层粘土矿物

为了解天津蓟县长城系串岭沟组地层中混层粘土矿物的组成和结构特征, 利用X射线粉晶衍射(XRD) 和高分辨透射电镜(HRTEM) 对其进行了深入研究.通过对比该区粘土矿物的自然干燥片、Ca离子饱和片、Ca饱和的乙二醇膨胀片、加热到375℃和550℃的乙二醇膨胀片获取的XRD衍射峰, 确定该区混层粘土矿物为伊利石/蒙脱石(I/S) 不规则混层矿物和绿泥石/蒙脱石(Chl/S) 不规则混层矿物.从高分辨透射电镜观察到I/S规则及不规则混层的晶格条纹像以及Chl/S不规则混层的晶格条纹像, 揭示了该区I/S混层和Chl/S混层的层间堆跺结构特征.该研究为蓟县中元古界典型剖面提供了重要的混层粘土矿物的结构信息.      

贵州绿豆岩中粘土矿物特征及其成因探讨

本文应用Ｘ射线衍射、红外光谱、差热分析，电子显微镜、化学分析、沉积相分析等方法，详细研究了贵州早、中三叠世间绿豆岩及其粘土矿物组成，确定了贵州绿豆岩中主要粘土矿物为伊利石、蒙脱石、高岭和伊利石／蒙脱石混层矿物。由于各地沉积环境和成岩条件的差异，分别形成伊利石粘土岩、蒙脱石粘土岩和高岭石粘土岩。探讨了绿豆及其粘土矿物的形成机理，为绿豆岩的开发利用提供了系统的新资料。     

川东华蓥山二叠系／三叠系界线附近粘土层中粘土矿物的类型及成因

对川东华蓥山二叠系／三叠系界线附近粘土层中的粘土矿物进行野外采样和室内X射线衍射分析,结果表明,这些粘土矿物主要由规则混层伊利石-蒙脱石组成,其中1个样品可能舍有少量不规则混层绿泥石-蒙脱石等粘土矿物。总地看来．该界线粘土层中的规则混层伊利石-蒙脱石中伊利石层的含量自下而上呈现减少的趋势,平均含量约83％,所经历的最大古地温在125-150℃之间。这些粘土矿物的构成和特征与前人在华南其他地区相同层位取得的成果总体上具有较好的一致性．显示了该粘土层成因的相同性及所具有的等时意义。不同地区粘土矿物构成的差异性（如高岭石的存在与含量）可能与二叠系／三叠系界线不整合的存在与否或间断时间有关,规则混层伊利石-蒙脱石的混层比则与埋藏历史和沉积-沉积期后的流体介质有关。     

川东华蓥山二叠系/三叠系界线附近粘土层中 粘土矿物的类型及成因

对川东华蓥山二叠系／三叠系界线附近粘土层中的粘土矿物进行野外采样和室内X射线衍射分析,结果表明,这些粘土矿物主要由规则混层伊利石-蒙脱石组成,其中1个样品可能舍有少量不规则混层绿泥石-蒙脱石等粘土矿物。总地看来．该界线粘土层中的规则混层伊利石-蒙脱石中伊利石层的含量自下而上呈现减少的趋势,平均含量约83％,所经历的最大古地温在125-150℃之间。这些粘土矿物的构成和特征与前人在华南其他地区相同层位取得的成果总体上具有较好的一致性．显示了该粘土层成因的相同性及所具有的等时意义。不同地区粘土矿物构成的差异性（如高岭石的存在与含量）可能与二叠系／三叠系界线不整合的存在与否或间断时间有关,规则混层伊利石-蒙脱石的混层比则与埋藏历史和沉积-沉积期后的流体介质有关。     

碳酸盐岩红土中1．4nm间层矿物及其环境意义

碳酸盐岩红土中１．４ｎｍ间层矿物及其环境意义朱立军（贵州工学院，贵阳５５０００３）关键词红土，间层矿物，土壤环境１．４ｎｍ间层矿物是指由绿泥石晶层与２：１型含水膨胀层交互连生所构成的不规划间层粘土矿物，其中２：１型含水晶层可以是蒙脱石层，也可以是蛭石...     

蒙脱石+伊/蒙混层+伊利石等粘土矿物混合物相X射线定量分析方法—模拟定量法

本文提出粘土矿物(特别是含伊/蒙不规则混层粘土矿物)混合物相的X射线定量分析方法——模拟定量法。着重解决在蒙脱石-不规则伊/蒙混层粘土矿物-伊利石组合中,伊/蒙混层粘土矿物的定量分析计算。模拟定量法是对以前的各种粘土矿物X射线定量分析方法的补充。用纯净的蒙脱石、伊利石、高岭石、绿泥石及各种伊/蒙混层比的伊/蒙混层粘土矿物,配制了各种不同组合的粘土矿物混合样品,制成定向薄膜片,进行了X射线分析,讨论了各种组合的粘土矿物混合物相X射线衍射图谱的特征,并在此基础上提出了粘土混合物相定量分析的方法。     

吐鲁番坳陷中——上侏罗统碎屑岩中的自生粘土矿物特征及其成岩意义

利用岩石薄片和扫描电镜观察以及Ｘ－衍射资料研究了吐鲁番坳陷中上侏罗统碎屑岩中的自生粘土矿物特征,发现碎屑岩中的自生粘土矿物主要有五种类型,即蒙脱石、伊利石－蒙脱石混层、伊利石、绿泥石和高岭石。自生粘土矿物的形成和转化取决于碎屑岩原始矿物组分及其成岩环境。蒙脱石的迅速转化和高岭石的大量析出与碎屑岩的大规模溶解有着密切的关系。根据自生粘土矿物的组合特征,可以有效地确定碎屑岩的成岩阶段及其孔隙发育特征。     

松嫩平原苏打盐渍土表层土壤黏粒矿物的组成分析

以松嫩平原内的前郭和大安两地苏打盐渍土表层土壤为供试土壤,采用Rigaku RIX 2000型荧光光谱仪和XRD—7000衍射仪,对土壤黏粒矿物组成进行了分析。结果表明:表层土壤黏粒(2μm)化学组成均以SiO_2、Al_2O_3和Fe2O3为主,其SiO_2/Al_2O_3 4,土壤风化脱硅作用较弱;土壤黏粒以2∶1型层状铝硅酸盐矿物为主,含有蒙脱石、伊利石—蒙脱石混层矿物、伊利石、伊利石—白云母混层矿物、蛭石、1∶1型层状铝硅酸盐高岭石以及少量2∶1∶1型绿泥石和石英及1.42 nm间层矿物。苏打盐渍土处于风化脱K作用阶段,土壤中混层及间层矿物较多,以蛭石—绿泥石、蒙脱石—绿泥石过渡矿物为主,为二八面体白云母和二八面体蒙脱石混层矿物。水田利用可使土壤黏粒中绿泥石增加,改善苏打盐渍土不良的结构。     

Clay mineralogy and geochemistry and their palaeoclimatic interpretation of the Pleistocene deposits in the Xuancheng section,southern China

A red soil profile in Xuancheng, Anhui province, southern China, in the middle to lower reaches of the Yangtze River, was investigated using X‐ray diffraction, X‐ray fluorescence spectrometer, and scanning electron microscopy. The mobile components K₂O and Na₂O and trace elements Ba and Sr of the Xuancheng section exhibit a general trend of decrease downward along the red soil profile, together with an increase downward of chemical index of alteration (CIA) values, suggesting more intense depletion in the lower portion than in the upper portion. The major components SiO₂, Al₂O₃ and Fe₂O₃, as well as SiO₂/Al₂O₃, SiO₂/Fe₂O₃ and Al₂O₃/Fe₂O₃ ratios, show notable fluctuations along the soil profile, indicating intense climatic oscillations in the area during the Pleistocene age. The clay mineral assemblage of the Xuancheng section can be generally subdivided into three groups, suggesting a general trend of three stages of climate changes. The lower portion of ～10.4–6.3 m depth has a lower illite content and higher abundance of kaolinite and illite–smectite (I/S) clays, indicating that a warm and wet climate prevailed over the episode of ca. 600–350 ka BP. A decrease in abundance of kaolinite and I/S clays and increase in illite content at a depth of ～6.3–2.2 m probably indicate a transition stage of climate change from warm/humid to cool/dry in the period ca. 350–80 ka BP. The higher illite content and lower abundance of kaolinite and I/S clays in the upper portion of ～2.2–0 m depth suggest that a relatively cool and dry climate dominated since ca. 80 ka BP. Based on changes in clay mineralogy and chemical indices of the sediments, seven warm/cold fluctuations were determined in the area since the Middle Pleistocene. Climate changes documented in the Xuancheng section are in agreement with the δ¹⁸O records of sediments from the equatorial Pacific Core V28‐238 and the loess–palaeosol sequences in the Loess Plateau of northwestern China. Correlated to the episode of S4 and S5 soil units in the Loess Plateau, the period of ca. 600–350 ka BP in the Xuancheng area was dominated by the particularly strong East Asia summer monsoon, as indicated by its most abundant kaolinite and I/S clays. Fluctuations in clay mineralogy along the Xuancheng soil profile were mainly controlled by both the East Asia summer and winter monsoons in response to the global changes in the Middle–Late Pleistocene. Copyright © 2009 John Wiley & Sons, Ltd.     

Clay petrology of the Upper Triassic/Lower Jurassic terrestrial strata of the Newark Supergroup,Connecticut Valley,U.S.A.

The clay mineralogy of the Newark Supergroup (Upper Triassic/Lower Jurassic) in the Connecticut Valley was studied by X-ray diffraction analysis. Clay minerals identified in 126 samples are illite, chlorite, smectite, kaolinite, vermiculite, expandable chlorite, mixed-layer illite/smectite, mixed-layer chlorite/smectite, and mixed-layer chlorite/vermiculite. In general, the rocks are illitic with subordinate amounts of chlorite. However, the various lithofacies in the Newark Supergroup are characterized by distinct clay-mineral assemblages. Red beds of floodplain origin contain clays mainly of detrital nature with 2M illite most abundant. Subordinate amounts of chlorite, smectite, vermiculite, kaolinite and mixed-layer illite/smectite are also present. An interstratified chlorite/vermiculite occurs in red mudstone underlying basalt flows. Lacustrine gray beds are generally characterized by the clay-mineral assemblage 1Md illite + chlorite with minor amounts of smectite ane expandable chlorite. An interstratified chlorite/smectite predominates in gray mudstone associated with perennial lake cycles in the East Berlin Formation. Black shales of deeper lacustrine origin contain the assemblage 1Md ifillite + trioctahedral smectite and traces of chlorite. Illite and smectite also occur as mixed-layer phases.In many respects, the distribution of clay minerals in the Connecticut Valley can be likened to the general scheme proposed for the Permo-Triassic basins of Europe and Africa. These display both vertical and horizontal variations in clay-mineral assemblages that reflect the chemical and spatiotemporal evolution of intrabasin depositional and diagenetic environments. Chemical data indicate that magnesium, especially, was concentrated in the black muds of large perennial lakes that intermittently occupied the Connecticut rift valley. Pore waters derived from these sediments played an important role in the development of Mg-rich 2 : 1 and interstratified clay minerals during early diagenesis.     

Illite-smectite Mixed-layer Minerals in the Alteration Volcanic Ashes under Submarine Environment

The clay mineralogy of the clay intervals interbedded with siliceous mudstones across the Permian-Triassic boundary (PTB) in Pengda, Guiyang, Guizhou province, was investigated by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The clay mineral assemblages of the sediments are mainly I/S clays and minor smectite, kaolinite, and illite as reveled by XRD analyses. The peak-shape parameters BB1 and BB2 of I/S clays of the representative clay bed PL-01 are 4.7° and 4.4°, and the peak position of the low angle reflection is at 6.8° 2θ (13.6 ), suggesting that the I/S clays has a IS type of ordering. However, the presence of multi-order reflections and their intensities are different from those of completely ordered 1∶1 mixed-layer I/S clay rectorite, indicating that I/S clays of the Pengda section have partially ordered IS structures. HRTEM observations show that most of the I/S clays exhibit an IS stacking ordering. However, in some areas within a IS particle, smectite layer is observed in doublets, triplets, and quartets, which are interstratified by various amounts of illite layers, suggesting the presence of other irregular stacking in addition to the major 1∶1 IS ordered stacking. Transformation of smectite layer into illite layers is also observed in the I/S clays, suggesting that the Pengda I/S clays are derived from smectite illitization, in good agreement with the clay mineral assemblage. The I/S clays of the Pengda section contain up to 45% to 95% smectite layer, the notably higher contents of smectite layer relative to those of other PTB stratigraphic sets in south China can be attributed to difference in alteration and smectite illitization processes due to different sedimentary environments.     

西昆仑山前陆盆地粘土矿物特征及其地质意义

为重建西昆仑山地区晚新生代的地质构造及环境演变过程,本文利用X射线衍射（XRD）及扫描电子显微分析（SEM）方法,对西昆仑山前陆盆地（叶城盆地）该时期沉积的一套磨拉石建造中的粘土矿物进行了研究。结果表明,在整个晚中新世到早更新世的沉积物地层中,粘土矿物的种类始终以伊利石和蒙脱石为主,含少量的绿泥石和高岭石。但伊利石、蒙脱石、高岭石的相对含量,以及伊利石结晶度值等均显示出明显的变化。在8~3.5 Ma B.P.期间,伊利石相对含量值和结晶度值均比较高,而蒙脱石相对含量低,并有少量的高岭石产出;在3.5~3.3 Ma B.P.期间,伊利石相对含量值和伊利石结晶度值均急剧降低,而相反,蒙脱石相对含量值急剧升高,高岭石基本消失;3.3~2.8 Ma B.P.期间沉积物的粘土矿物参数与8~3.5 Ma B.P.时期的粘土矿物参数非常接近;而2.8~1.8 Ma B.P.期间沉积物的粘土矿物参数则与3.5~3.3 Ma B.P.期间的粘土矿物参数相类似。根据沉积物中的粘土矿物特征变化规律可以推断,物源区母岩成分的变化是粘土矿物特征变化的主要原因,古气候古环境变化则是次要影响因素。粘土矿物特征的变化规律显示西昆仑山体在晚新生代具有不均匀的阶段性隆升的特点,在3.5 Ma B.P.、3.3 Ma B.P.、2.8 Ma B.P.左右分别发生了三次明显的构造隆升事件,而且总伴随着风化母岩成分的变化。物源区在早更新世中期（12.5 Ma B.P.)很可能处于干旱的古气候古环境中。     

Clay minerals in sediments of the hydrothermally active southern trough in the Guaymas Basin (Gulf of California)

The results of the study of clay mineral alterations in Upper Pleistocene sediments of the southern trough in the Guaymas Basin (Gulf of California) due to the influence of hydrothermal solutions and heat produced by sill intrusions are discussed. Core samples from DSDP Holes 477 and 477A were taken for the analysis of clay minerals. Application of the method of modeling X-ray diffraction patterns of oriented specimens of the finely dispersed particles made it possible to establish the phase composition of clay minerals, determine their structural parameters, and obtain reliable quantitative estimates of their contents in natural mixtures. The modeling data allowed us to characterize reliably the transformation of clay minerals in sediments of the hydrothermally active southern trough in the Guaymas Basin. In Upper Pleistocene sandy–clayey sediments of the southern trough, changes in the composition of clay minerals occurred under the influence of a long-living hydrothermal system. Its lower part (interval 170.0–257.5 m) with maximum temperatures (~300°C) was marked by the formation of chlorite. Terrigenous clay minerals are not preserved here. Saponite appears at a depth of 248 m in the chlorite formation zone. Higher in the sedimentary section, the interval 146–170 m is also barren of terrigenous clay minerals. Sediments of this interval yielded two newly formed clay minerals (chlorite and illite), which were formed at lower temperatures (above 180°C and below 300°C, approximately up to ~250°C), while the relatively low-temperature upper part (110–146 m) of the hydrothermal system (from ~140°C to ~180°C) includes the mixture of terrigenous and newly formed clay minerals. Terrigenous illite is preserved here. Illitization of the mixed-layer illite–smectite was subjected to illitization. The terrigenous montmorillonite disappeared, and chlorite–smectite with 5–10% of smectite layers were formed. In the upper interval (down to approximately 110 mbsf), the composition of terrigenous clay minerals remains unchanged. They are composed of the predominant mixed-layer illite–smectite and montmorillonite, the subordinate illite, mixed-layer chlorite–smectite with 5% of smectite layers, mixed-layer kaolinite–smectite with 30% of smectite layers, and kaolinite. This composition of clay minerals changed under the influence of sill intrusions into the sedimentary cover at 58–105 m in the section of Hole 477. The most significant changes are noted in the 8-m-thick member above the sill at 50–58 m. The upper part of this interval is barren of the terrigenous mixed-layer illite–smectite, which is replaced by the newly formed trioctahedral smectite (saponite). At the same time, the terrigenous dioctahedral smectite (montmorillonite) is preserved. The composition of terrigenous clay minerals remains unchanged at the top of the unit underlying the sill base.     

台湾海峡表层沉积物中黏土矿物特征及物质来源

利用X射线衍射仪,对比分析台湾海峡及周边表层沉积物的黏土矿物特征,讨论长江、福建和台湾河流对海峡黏土矿物的贡献程度。福建河流（闽江）的黏土矿物以高岭石为主（>40％）,其次是伊利石（30％）和绿泥石,不含蒙脱石;长江和浙闽泥质区的黏土矿物特征是伊利石含量最高（61％～66％）,其次是绿泥石（16％～17％）和高岭石（10％～13％）,少量蒙脱石（6％～9％）。台湾河流（浊水溪）黏土矿物组合为伊利石（>70％）和绿泥石,不含高岭石和蒙脱石为特征。台湾海峡高岭石含量由西向东明显减少,说明高岭石主要来自福建的河流。〖JP2〗台湾海峡50 m等深线以东区域的黏土矿物具有高的伊利石和绿泥石含量,低的蒙脱石和高岭石含量,且伊利石的化学指数和结晶度值都明显低于长江和福建的河流,反映台湾河流的物质来源。在台湾暖流作用下,台湾河流为台湾海峡中北部提供了大量的伊利石和绿泥石。福建近海的黏土矿物主要是由福建河流提供的,但在平潭岛周边海域的黏土矿物可能有长江物质的混合。〖JP〗     

Clay Minerals in an Active Hydrothermal Field at Iheya‐North‐Knoll,Okinawa Trough

Iheya‐North‐Knoll is one of the small knolls covered with thick sediments in the Okinawa Trough back‐arc basin. At the east slope of Iheya‐North‐Knoll, nine hydrothermal vents with sulfide mounds are present. The Integrated Ocean Drilling Program (IODP) Expedition 331 studied Iheya‐North‐Knoll in September 2010. The expedition provided us with the opportunity to study clay minerals in deep sediments in Iheya‐North‐Knoll. To reveal characteristics of clay minerals in the deep sediments, samples from the drilling cores at three sites close to the most active hydrothermal vent were analyzed by X‐ray diffraction, scanning electron microscope and transmission electron microscope. The sediments are classified into Layer 0 (shallow), Layer 1 (deep), Layer 2 (deeper) and Layer 3 (deepest) on the basis of the assemblage of clay minerals. Layer 0 contains no clay minerals. Layer 1 contains smectite, kaolinite and illite/smectite mixed‐layer mineral. Layer 2 contains chlorite, corrensite and chlorite/smectite mixed‐layer mineral. Layer 3 is grouped into three sub‐layers, 3A, 3B and 3C; Sub‐layer 3A contains chlorite and illite/smectite mixed‐layer mineral, sub‐layer 3B contains chlorite/smectite and illite/smectite mixed‐layer minerals, and sub‐layer 3C contains chlorite and illite. Large amounts of di‐octahedral clay minerals such as smectite, kaolinite, illite and illite/smectite mixed‐layer mineral are found in Iheya‐North‐Knoll, which is rarely observed in hydrothermal fields in mid‐ocean ridges. Tri‐octahedral clay minerals such as chlorite, corrensite and chlorite/smectite mixed‐layer mineral in Iheya‐North‐Knoll have low Fe/(Fe + Mg) ratios compared with those in mid‐ocean ridges. In conclusion, the characteristics of clay minerals in Iheya‐North‐Knoll differ from those in mid‐ocean ridges; di‐octahedral clay minerals and Fe‐poor tri‐octahedral clay minerals occur in Iheya‐North‐Knoll but not in mid‐ocean ridges.     

Clay mineralogy, grain size distribution and their correlations with trace metals in the salt marsh sediments of the Skallingen barrier spit, Danish Wadden Sea

To understand the behavior of trace metals in the salt marsh at Skallingen, Danish Wadden Sea, we investigated a profile from surface to 25?cm depth of the salt marsh sediment, focusing primarily on clay mineralogy and grain size distribution of the sediments and their relationship with trace metals. The clay assembly of the sediment consists of illite, kaolinite and much less chlorite and smectite. The major clay minerals of illite, kaolinite as well as chlorite correlate very poorly with all the trace metals investigated, due probably to the weak competing strength of these clays compared with the other adsorbents and to low availability of the mobile trace metals in the system. Correlation between trace metals and clay minerals may therefore be used as an indicator in environmental assessment. Fine grain fractions of the sediment increased markedly after salt marsh invasion in about 1931 but decreased after 1964. This increase was contributed mainly by the grains finer than 20???m while the fraction of 40?C63???m actually decreased soon after the invasion. The relation between most of the trace metals and grain size distributions is close in general but far from linear. The drastic turning point is observed at about 30???m, around where the correlation coefficient r drops from 0.8 to 0.1. Adsorption is the controlling mechanism for the behavior of trace metals in the salt marsh. Fe/Mn (hydr)oxides and organic matter play the key role.     

Clay gouge

Clays are a common component of fault gouge, but their genesis and importance in fault evolution is poorly understood. We present preliminary evidence that clays participate in extensive mineral reactions and microfabric changes during faulting. Rather than thinking of clay reactions as a consequence of mechanical processes or fault localization following diagenetically altered horizons, we see the interplay between clay mineral reactions and mechanical processes as a single, integrated process. Furthermore, faulting may lower kinetic barriers to low-temperature (∼100°C) mineral reactions that are common in sedimentary rocks.Our most striking example of fault diagenesis-deformation is a profile of %illite in mixed-layer illite/smectite in shales beneath the Lewis Thrust, Canada. Whereas burial diagenesis caused minimal smectite-to-illite reaction, shales within meters of the thrust are almost completely converted to illite. The consequences of these changes are manifested in geochemical, geochronologic and microfabric characteristics of clay gouge. In this example, faulting has helped overcome a kinetic barrier in the smectite-to-illite reaction without appreciable addition of heat. In another example we infer that dissolution–precipitation reactions continue during faulting even when smectite has already been completely transformed to illite.If mineral reactions intimately interact with mechanical processes in shallow-crustal faults, then our current understanding of the mechanical and hydraulic properties of fault zones may be incomplete. Syndeformational mineral reactions and associated fabric changes could make faults much weaker than would be expected from evaluation of the static mineral assemblage of gouge and single crystal properties. Syndeformational mineral reactions may promote fault slip (affecting earthquake activity) in gouge-bearing faults under stress conditions considerably lower than predicted from static mineral properties. In addition, fault-induced dissolution-precipitation reactions may contribute to fault localization.     

澄湖SC7孔沉积物粘土矿物特征及其古地理意义

苏州澄湖湖底残留有一条NNW—SSE延伸且已被淤平的古河道。通过对湖心区古河道段SC7孔沉积物的粘土矿物XRD分析及与湖底硬粘土（Q3）、湖岸区沉积（Q4）和长江口滩地现代沉积的比较,表明古河道充填沉积中的粘土矿物主要为伊利石,其次为高岭石、绿泥石、蛭石,还有少量蒙皂石及蛭石/绿泥石混层矿物;其中的伊利石和绿泥石含量均明显偏高,高岭石含量则偏低,伊利石结晶度也较高。粘土矿物组合兼具太湖流域地带性粘土矿物和长江口沉积物的特点,表明古河道充填沉积既有来自本流域表层物质和澄湖扩大过程中的湖岸崩积,也受到长江物源的影响。这一沉积过程也说明古河道在最大海侵时涨潮流和洪水引起海水和江水的频繁倒灌,直至淤塞和淹废。