恒山杂岩的年代学和钕同位素演化

同位素地质年代学研究证实了恒山地区古老大陆壳的存在,斜长角闪岩包体的Sm-Nd等时线,13个点构成两条平行线,年龄为2.8Ga,∈_(Nd(t))分别为2.27Ga和5.52Ga.A组包体与年龄为2.23Ga的五台群火山岩的∈_(Nd(t))值几乎一样(2.14Ga),表明两套幔源岩派生于同一源区,华北地区新生代火山岩和元古代基性,超基性岩的∈_(Nd(t))也在这一范围,因此,认为该区的地幔源自3.5Ga以来∈_(Nd)值几乎没有明显的改变。B组包体∈_(Nd(t))值较高可能是由于五台群火山活动对早期包体混染的结果。     

塔里木盆地周缘新元古代冰期事件与古老烃源岩发育

正四川盆地震旦系含油气系统已被证实为我国新元古界第一个具有商业价值的原生型气藏,而与扬子板块在同时期具有亲缘性的塔里木盆地新元古界油气资源一直未取得突破。塔里木盆地新元古界埋藏较深,钻遇南华系-震旦系的井位非常少,盆地深部层系的成像品质较差,同时新元古界本身缺乏可进行有效对比的古生物化石。诸多因素造成塔里木盆地新元古界划分与对比关系不清,地层格架模糊,直接导致后续深入研究无法进行。然而,     

塔里木盆地西部古盐岩同位素地球化学与成钾预测研究

我国钾盐资源紧缺，寻找优质大型钾盐矿床一直是国家资源普查的重要目标这一。塔里木盆地在其地史发展过程中，曾与广海相通，多期海水的侵入和间断，以及适宜的构造、古地里环境具备成钾的基本地质条件，因此一直被列为我国寻找古钾矿的重点地区。为了更准备地判断其成盐的海陆相特征，即成盐物质的主要来源，以及岩盐沉积之前的古卤水蒸发浓缩阶段，预测更有前景的成钾远景区，论文选择了蒸发岩沉积序列中的石膏及石盐矿物，分别分析了其硫同位素及氯同位素分布特征。结果表明，非还原环境下沉积的石膏硫同位素可以准确判断盐岩沉积的海相、陆相和海陆交互沉积特征，氯同位素可以判断岩盐的沉积阶段。应用这两个同位素新指标分析，塔里木盆地西部喀什次级构造凹陷晚白垩世盐岩沉积接近海相沉积类型，而且岩盐沉积阶段较晚，是一最有利成钾远景区。     

Mineralogical studies of pyropes in kimberlites from China

Based on the measurements of refractive index,specific gravity,unit cell parameter,and mineral chemistry and infrared absorption spectrum analyses of pyropes in kimberlites from China,systematic studies of the Physical properties and compositional variations of pyropes of different colors and diverse paragenetic types,within and between kimberlite provinces have been undertaken,The origin of pyropes in the Kimberlites and the depth of their formation have been discussed.Pyropes of the purple series are different from those of the orange series in physical and chemical properties,for exaple,pyropes of the puple series are higher in α0,RI,SG,Cr2O3,MgO,Cr/(Cr Al),Mg/(Mg Fe),and Mg/(Mg Ca),and lower in Al2O3,Fe2O3 FeO than those of the orange series.The classification of garnets in kimberlites from china by the Dawson and Stephens‘ method(1975) has been undertaken and clearly demonstrates that pyropes of diamond-rich kimberlites contain much more groups than those of diamond-poor,especially diamond-free kimberlites.The higher in α0,RI,SG,Cr2O(3.Cr/(Cr Al),knorringite and Cr-component the pyropes are ,the richer in diamond the kimberlites will be.The infrared absorption spectrum patterns of pyropes change with their chemical composition regularly,as reflected in the shape and position of infrared absorption peaks.Two absortpion bands at 862-901 cm^-1 will grade into degeneration from splitting and the absorption band positions of pyropes shift toward lower frequency with increasing Cr2O3 content and Cr/(Cr Al) ratio of pyropes,LREE contents of orange pyrope megacrysts are similar to those of porple pyrope macrocrysts,but the former is higher in HREE than the latter,showing their different chondrite-normalized patterns.The formation pressures of pyropes calculated by Cr-component,Ca-component,knorringite molecules of pyropes show that some pyropes of the purple series in diamondiferous kimberlites fall into the diamond stability field.but all pyropes of diamond-free kimberlites lie outside the diamond stability field.The megacrysts were formed through early crystallization of kimberlites magma at high pressure condition,the majority of the purple pyrope macrocrysts have been derived from disaggregated xenoliths but the minoirty of them appear to be fragments of the discrete megacryst pyropes,or phenocrysts.     

中国东南沿海中生代成岩-成矿作用的独特性

本文概述了中国东南沿海中生代陆相火山-侵人杂岩的时空分布、岩石系列和组合、成因类型和矿床空间分带、成矿时代诸特征,指出中国东南沿海火山岩带或成矿带较之环太平洋火山岩带或成矿带其他组成部分,其岩浆作用、成矿作用具有明显的独特性,并进而指出该区成岩-成矿地质背景、板块作用方式的独特性。     

达拉布特型碱性花岗岩源岩特征初步探讨：来自稳定同位素和微量元素 …

根据稳定同位素组成特点和微元素组成及岩石形成演变的分析,对达拉布特型碱性花岗岩的源岩进行了初步探讨。指出其源岩具有混源特点：同时存在地幔物质和上地壳物质。结合岩石化学组成特点,源岩的化学组成可能与含基性、中基性火山岩的麻粒岩相岩石相似。     

软岩地区钻孔嵌岩灌注桩承载力确定的探讨

单桩承载力的确定,在桩基础的设计中占有重要地位。但在软岩地区由于地层岩性的不同,单桩承载力的实际工作性状与国家规范的规定之间不尽相同。根据实测资料对软岩地区的单桩承载力的确定方法进行探讨,综合考虑嵌岩段侧阻力与端阻力之间的相互协调对嵌岩段所能提供的承载力的影响,提出一种新的计算方法,并结合工程实例,进行验证。