Crystallinity and metamorphism of illite from Triassic strata in Henan County of Qinghai Province

In order to verify the Triassic stratum metamorphism in this area, the crystallinity of illite in mudstone (shale) of Triassic stratum was analyzed and tested during the 1:50 000 regional mineral geological survey (I47E007023, I47E008023, I47E009023,1I47E009024)in Tuoyema area of Henan Mongolian Autonomous County in Qinghai Province. According to the experimental results of 30 samples, the crystallinity index of Triassic mudstone (shale) illite Kübler in Zongwulong-Zeku stratigraphic division in the north is 0.312-0.537, and the cell parameter b₀ is 0.898-0.903 2 nm. The metamorphic temperature is less than 350 ℃, with the grape-chlorite and zeolite facies. The crystallinity index of Triassic mudstone (shale) illite Kübler in the western inclined mountain stratigraphic division in the south is 0.21-0.318, and the b₀ value is 0.898 1-0.901 4 nm. The metamorphic temperature is mainly between 200 and 350 ℃, with the local temperature above 350 ℃ and grape-chlorite and greenschist facies. It is considered that the regional metamorphism grade in this area is very low or has no regional metamorphism. The metamorphism degree of the western dipping mountain stratum in the south is slightly higher than that of Zongwulong-Zeku stratum in the north. The measured metamorphic facies belts are not consistent with the previous thought, that is "regional low temperature dynamic metamorphism and low greenschist facies metamorphic belts", and the degree of metamorphism is relatively lower. It is confirmed that there is no large area regional metamorphism in the Triassic strata of Henan County in Qinghai Province, but only very low-level regional metamorphism.     

由伊利石结晶度研究桂西右江地区区域极低级变质作用

运用伊利石结晶度Kübler指数将桂西右江地区下三叠统罗楼群和中三叠统百逢组下段划归为浅层变质带(K.I△2θ°为0.22～0.25);将中三叠统百逢组上段和河口组划归为近变质带,中三叠统百逢组上段为高级近变质带(K.I△2θ°为0.26～0.33);中三叠统上部河口组为低级近变质带(K.I△2θ°为0.38～0.40),不排除局部为成岩带的可能.地层柱自下向上,伊利石结晶度Kübler指数由小变大,变质程度由高变低,而且,变质作用级别与岩层在地层柱中位置协调以及变质带边界与地层界线趋于一致,证明为区域埋藏极低级变质作用.凌云明山金矿区剖面矿体和百逢组各层段伊利石结晶度Kübler指数为0.42～0.50,属成岩带,且没有明显时空变化规律.     

伊利石结晶度及其在低温变质研究中若干问题的讨论

文中介绍与伊利石结晶度相关的伊利石矿物新的定名方案;讨论了伊利石结晶度的结晶学基础与Scherrer方程式的关系;讨论了三个重要的伊利石结晶度指数Weaver、K櫣bler和Weber指数的关系,并介绍推导的Weaver、K櫣bler和Weber指数的理论关系式;评价了衍射仪测量条件对结晶度数值的影响和三套伊利石结晶度标样的作用以及成岩带、变质带与葡萄石-绿纤石相、沸石相、绿纤石-阳起石亚相对比的依据。建议(1)停用绢云母一词;(2)建立可供各实验室使用的具有晶体结构和晶体化学参数和多型参数的伊利石结晶度标样;(3)建议多开展规范的可进行国际对比的低温变质研究,划分出与国际上一致的成岩带和近变质带,不仅利于低温变质作用理论的研究,而且由于成岩带到近变质转变带是重要的煤气油的生成带,也利于中国煤气油资源的勘探与开发,利于国民经济的长远持续发展。     

伊利石结晶度Kübler指数的校正与近变质带的确定

就像用"砝码"标定"称"来测量物质质量一样,伊利石结晶度的测量也需要这样的"砝码"标定它的测量工具——衍射仪,从而能够进行伊利石结晶度的测量和对比。这个砝码就是伊利石结晶度标样或称伊利石结晶度国际标样。第2届Kübler-Frey国际研讨会伊利石结晶度圆桌会议就伊利石结晶度标样和近变质带的确定的问题进行了深入的讨论。会议一致认为,用伊利石结晶度标样校正X射线衍射仪是极为重要和必要的,没有进行标样校正的伊利石结晶度数据将被拒绝发表,经过伊利石结晶度国际标样校正后的伊利石结晶度数据才可用于近变质带的划分和国际对比。本文就伊利石结晶度测量的有关衍射仪类型与差别,衍射仪系统,测量条件,样品的影响和国际标样对仪器的校正等问题进行了分析研究。结果表明不同型号仪器,同型号仪器不同测量条件与状态,样品的不同制备方法都将影响伊利石结晶度Kübler指数的测量。指出只有使用国际标样才可校正测量的伊利石结晶度Kübler指数,从而达到消除偏差准确划分近变质带的标准和进行国际对比的目的。     

极低级变质作用和极低级变质带综述

极低级变质作用是指变质作用最低级的部分，包括成岩作用和浅层变质作用，其变质温度范围大体介于１５０－３７０℃之间。本文简要地对极低级变质作用和极低级变质带的特征和研究领域进行综述，可以看出，通过极低级变质作用和极低级变质带的研究，能够提供造山带、沉积盆地演化及板劈理发育等有关地球动力学过程和流变状态信息；强调指出进一步研究极低级变质作用和极低级变质带的必要性。     

川西北壤塘地区三叠纪西康群极低级变质作用

通过区域地质调查和伊利石的结晶度指数、晶格参数（bo）的测定，揭示川西北壤塘地区三叠纪西康群遭受了区域极低级变质作用，进一步讨论区域极低级变质作用与构造变形的关系，并指出区域极低级变质作用是成岩－埋藏变质作用（造山前）和同造山变质作用的综合结果。     

有机质热演化与极低级变质作用

岩石中有机质热演化特征可以灵敏于反映岩石的成岩作用到变质作用之间（即极低级变质作用）的温度、压力变化情况。笔者对有机质热变指标在极低级变质作用界线、变质带划分和变质作用温度、压力和时间演化等方面的应用进行了综述和探讨。     

青藏高原可可西里地区三叠系巴彦喀拉山群低级-极低级变质作用

针对青藏高原可可西里的三叠系巴彦喀拉山群低级-极低级变质岩,利用X射线粉晶衍射分析确定了其矿物的共生组合、伊利石的结晶度Kubler指数(K)和b0值,并根据伊利石结晶度K和b0值对其区域变质作用的温压条件、分带、变质相进行了详细研究,得出了工作区5个不同岩性组合带的变质作用特征:昆仑山脉带属中压浅变质-近变质带,具葡萄石-绿纤石相和绿片岩相;不冻泉-库赛湖带属中压浅变质带,具绿片岩相;楚玛尔河带属中压近变质带,具葡萄石-绿纤石相;直达日旧带属中压浅变质带,具绿片岩相;五道梁带属中压近变质带,具葡萄石-绿纤石相.     

若尔盖地块震旦系-志留系极低级变质作用研究

对若尔盖地块震旦系—志留系中黏土矿物进行了X衍射分析。结果表明,震旦系至志留系中伊利石结晶度0.25相似文献   

极低级变质作用及其研究方法

近年来国际上极低级变质作用的研究进展包括综合运用了伊利石结晶度等各项指标 ,将极低级变质带划分为成岩带、近变质带和浅变质带 ,成岩带和近变质带又可进一步划分为低级成岩带、高级成岩带、低级近变质带和高级近变质带 ;研究了伸展背景、阿尔卑斯碰撞背景和增生背景下的极低级变质作用 ;进一步理解了矿物的转变过程 ,建立了变质泥质岩石的矿物反应系列。即变质泥质岩石的二八面体矿物反应系列 ,为蒙皂石—伊 /蒙混层 (I/S)—伊利石—白云母 ;对应变质镁铁质岩石的三八面体矿物反应系列 ,为蒙皂石—绿泥石 /蒙皂石混层 (C/S)—绿泥石。岩石微构造也发生同步变化 ;明确了广泛应用的伊利石结晶度的本质是雏晶大小的一种量度 ,也与晶格应变有关 ,主要受反应动力的控制 ;建立了系统的研究技术方法 ,包括野外采样方法、室内X光衍射法 (XRD)、透射电镜法 (TEM )、地质温度计、地质压力计、岩石学方法、同位素地质学方法等     

内蒙古中部地区晚古生代地层接触变质作用研究初探

内蒙古中部晚古生代地层由于中生代岩浆的侵入,部分发生接触变质,变质程度多处于沸石相或葡萄石绿纤石相。通过对典型剖面的泥质岩石中的粘土矿物、伊利石结晶度以及镜质体反射率的分析,得出以下结论：（1）粘土矿物以伊利石和绿泥石为主,只在极少数样品中有伊蒙混层和蒙脱石,多数缺乏伊绿混层;（2）伊利石结晶度为022~040;（3）镜质体反射率Ro值为15~40。其结果表明：在岩浆侵入地区有小规模的接触变质,为极低级变质带,并未发生大规模的低绿片岩相的区域变质,而且这种变质只影响到晚二叠世以前沉积的地层和油气,分布范围有限。     

Adaminaby Group west of Batemans Bay: Deformation and metamorphism of the Narooma accretionary complex,NSW

This study provides new structural data that show that the Adaminaby Group is part of the Narooma accretionary complex and has been overprinted by HT/LP metamorphism associated with Middle Devonian Moruya Suite intrusions. The grade of metamorphism based on Kübler Indices is the same in the Wagonga and Adaminaby Groups at Batemans Bay inferring that these rocks were involved in the same accretionary event. White micas in slates of the Adaminaby Group record apparent K–Ar ages of 384.6 ± 7.9 Ma and 395.8 ± 8.1 Ma. These ages are believed to represent the age of Middle to Upper Devonian Buckenbowra Granodiorite. Kübler Index values indicate lower epizonal (greenschist facies) metamorphic conditions and are not influenced by heating in metamorphic aureoles of the plutons. All b cell lattice parameter values are characteristic of intermediate pressure facies conditions although they are lower in the metamorphic aureole of the Buckenbowra Granodiorite than in the country rock, defining two areas with dissimilar baric conditions. East of the Buckenbowra Granodiorite, b cell lattice parameter values outside the contact aureole (x = 9.033 Å; n = 8) indicate P = 4 kb, and assuming a temperature of 300°C, infer a depth of burial of approximately 15 km for these rocks with a geothermal gradient of 20°C/km. In the metamorphic aureole of the Buckenbowra Granodiorite, b cell lattice parameter values (x = 9.021 Å; n = 41) indicate P = 3.1 kb inferring exhumation of the Adaminaby Group rocks to a depth of approximately 11 km prior to intrusion. A geothermal gradient of 36°C/km operated in the aureole during intrusion. An extensional back-arc environment prevailed in the Adaminaby Group during the Middle to Upper Devonian.     

河南陕县黄连垛组的发现及其地质意义

前人将河南省陕县李村龙脖一带覆盖于熊耳群之上的碎屑岩-碳酸盐岩组合划分为高山河群和官道口群龙家园组。本次研究,通过剖面测制和区域对比,发现该套地层实际为长城系汝阳群云梦山组—洛峪口组、蓟县系黄连垛组及寒武系罗圈组、辛集组、朱砂洞组、馒头组。同时,在黄莲垛组中发现的假裸枝和卷心菜叠层石,可与官道口群龙家园组—巡检司组对比,证实了官道口群和黄连垛组是华北陆块南缘在蓟县纪形成的同一套碳酸盐岩沉积。     

河南省杞县地下水形成条件研究

河南杞县在天然条件下,中、深层地下水的补给主要由侧向径流补给,其次为浅层地下水的越流补给。浅层地下水位高于中、深层地下水位,二者之间为薄层或透镜状粉土及粉质粘土,浅居地下水可补给中、深层水。     

河南省嵩县地质灾害风险评价

基于ArcGIS环境下,通过选取河南省嵩县区域高程、地貌、工程岩组、植被覆盖度、距构造距离、距水系距离、坡度、坡向等 8个因子建立危险性评价模型,易损性选取建筑物、人员和交通等 3 个承灾因子,分别采用信息量模型和层次分析法对河南省嵩县区域进行地质灾害易发性、危险性和易损性评价。研究结果表明,嵩县区域划分为低风险区面积为965.34 km2,占嵩县区域面积32%;中风险区面积为1114.65 km2,占嵩县区域面积的37%;高风险区面积为826.23 km2,占嵩县区域面积的27%;极高风险区面积为102.68 km2,占嵩县区域面积的3%。研究成果可应用于嵩县防灾减灾及地质灾害风险管控等方面。     

吉林省东部石炭-二叠系伊利石的成因标志

吉林东部石炭-二叠系主要是一套泥质岩石, 其详细深入的矿物学工作尚不多见。利用JSM-6700F场发射电镜及INCA能谱仪,研究了伊利石的显微形貌和微区成分。采用D/max-2500 X-射线衍射仪,研究了伊利石的结晶度、多型和b₀值。结果表明:研究区伊利石结晶度变化于0.26~0.77,平均值为0.44;伊利石（白云母）多型有3种类型,分别为1M_d型、1M_d+2M₁混合型和2M₁型;伊利石（白云母）b₀值为8.996~9.045,平均值为9.007Å。石炭系伊利石结晶度变化于0.26~0.50,平均值为0.35,主要呈2M₁多型,b₀平均值为9.011Å,主要是低级近变质带的产物;二叠系伊利石结晶度变化于0.26~0.50,平均值为0.42,主要为1M_d+2M₁混合型多型,b₀平均值为9.004Å,主要为晚期成岩带的产物。     

Diagenesis and very low-grade metamorphism of volcaniclastic sandstones from contrasting geodynamic environments, North Island, New Zealand: the Murihiku and Waipapa terranes

Abstract The Mesozoic Murihiku and Waipapa terranes are two accretionary wedges of linked forearc and trench sediments, respectively, that were juxtaposed in the early Cretaceous.
Late Triassic to late Jurassic Murihiku terrane volcaniclastic sediments are folded into a regional syncline and have been diagenetically altered. There is a general relationship between zeolite occurrence, clay mineralogy, vitrinite reflectance and stratigraphic position. Youngest Jurassic sediments contain heulandite, analcime and stilbite, whereas late Triassic to mid-Jurassic sediments have laumontite and heulandite (in detail the zeolite distribution is complicated). Tuffaceous horizons on the eastern limb of the syncline are calcitized rather than zeolitized. Post-diagenetic fractures associated with uplift are laumontite-filled. The inferred geothermal gradient is c. 15° C km⁻¹.
The Waipapa terrane is an accretionary complex dominated by imbricated terrigenous sediments of Triassic and Jurassic age with enclosed Permian to Jurassic pelagic sediments and basalts. Late Jurassic sediments are massive volaniclastic sandstones. The sediments are non-foliated, and metamorphic minerals in the massive sandstones have crystallized in specific domains. The observed metamorphic succession of prehnite-pumpellyite and pumpellyite-actinolite facies assemblages was overprinted in the imbricated rocks during a thermal event that was late in the deformation sequence and broadly coincident with hydraulic fracturing and veining.
The metamorphic successions in the two terranes and their relationships to structural features are in excellent accord with accretionary complex models.     

河南卢氏夜长坪钼钨矿床成矿条件及找矿远景分析

夜长坪钼钨矿床是豫西地区进行隐伏矿预测并取得找矿成功的典型案例.通过对矿床特征及成矿控制条件的分析研究,认为该钼钨矿床位于地幔隆起与凹陷区之间的地壳厚度增大部位,受矿源层官道口群龙家园组白云岩,近东西向和北东向断裂构造交汇部位侵入的燕山期中酸性隐伏小岩体控制,矿体就位于隐伏小花岗斑岩体接触带的夕卡岩中,属(大型)斑岩-矽卡岩型钼钨矿床.在此基础上,结合矿区外围的地质物化探测量成果,提出夜长坪钼矿区外围南部十八盘-大角寺一带为钼钨找矿的远景区.     

Very Low-Grade Metamorphism of Clastic Rocks from the Meso-Neoproterozoic and the Paleozoic along the Profile Yueyang-Linxiang in Northeastern Hunan Province and Its Geological Implications

This study uses illite crystallinity,chlorite crystallinity,illite polytypes,the b_0 cell-dimension of K-white mica,clay mineral assemblages and mineral geothermo-geobarometers to investigate the overprint of diagenesis and metamorphism on the Meso-Neoproterozoic and the Lower Paleozoic along the profile Yueyang-Linxiang in northeastern Hunan Province,China.Illite crystallinity Kbler index(KI) of the 2μm fractions ranges from 0.225 to 0.485°Δ2θ while chlorite crystallinity Arkai index(AI) ranges from 0.244 to 1.500°Δ2θ.This indicates that the Meso-Neoproterozoic and the Lower Paleozoic along the profile Yueyang-Linxiang were overprinted with diagenesis and anchi- to epimetamorphism.Peak metamorphic temperature is estimated with the IV site chlorite geothermometer roughly at 360℃.The b_0 cell dimension values of illites(K-mica) range from 0.9002 to 0.9054 nm and,on average,at 0.9030 nm for the Meso-Neoproterozoic.Based on cumulative frequency curves of illite(K-mica) b_0 cell dimension,the peak metamorphic pressure of the MesoNeoproterozoic along the profile Yueyang-Linxiang is derived of an intermediate pressure type.Most illites occur in the 2M_1 polytype and some of them in a mixture of 2M1+1M types especially those in the Paleozoic.This result partly agrees with the conclusion of the lower greenschist and greenschist facies of the Lengjiaxi and Banxi Groups.However,it is not agreed with the sedimentary cover from the Sinian to the Lower Paleozoic or from the Banxi Group to the Lower Paleozoic.Crustal thickening due to "collision" between the Yangtze and Cathaysia blocks led to an increase in the thickness of the Meso-Neoproterozoic to ca.14 km and resulted in a temperature increase in those rocks due to burial.The very low grade to low grade metamorphism overprinting the Meso-Neoproterozoic implies that the so called "Chiangnania or Jiangnan orogen" was no relative with the "Grenvillian orogeney;instead,it might be a continuous amalgamation product between the Yangtze and Cathaysia blocks.