南阿尔金花岗岩锆石Lu-Hf同位素特征及岩石成因

在以往工作的基础上,结合本文的岩石地球化学研究,将南阿尔金花岗岩划分为5期,第1期花岗岩组合为石英闪长岩+花岗闪长岩+二长花岗岩,具有I型花岗岩的属性,时代460 Ma;第2期花岗岩组合为花岗闪长岩+二长花岗岩+正长花岗岩,也具有I型花岗岩的特征,时代为435~450 Ma;第3期花岗岩组合为二长花岗岩+正长花岗岩+碱长花岗岩,具有A型花岗岩的属性,时代为385~411 Ma;第4期花岗岩组合为花岗闪长岩+二长花岗岩,时代为343~352 Ma,具有S型花岗岩的地球化学属性;第5期花岗岩组合为石英闪长岩+二长花岗岩+正长花岗岩,具有I型花岗岩的地球化学特征,时代为265 Ma。各期花岗岩锆石Lu–Hf同位素分析表明,ε_(Hf)(t)值大多数为正值,少数继承性锆石为负值,反映了它们的源岩以新生地壳为主,同时,也混有少量的古大陆壳的成分。根据年代学和岩石地球化学研究结果,结合区域地质特征,我们认为第1期(465~469 Ma)花岗岩浆活动可能与洋壳的俯冲作用有关;第2期(435~450 Ma)岩浆活动可能是碰撞后环境;第3期(404~411 Ma)岩浆活动可能与板块碰撞后造山带块体均衡调整、伸展有关,第4期(343~352 Ma)、第5期(265 Ma)岩浆活动可能与造山带深部块体的拆沉作用有关。     

沉积物不同提取态有机物特征及水文地球化学意义——以河套盆地典型研究区为例

地下水系统中有机物（OM）特征和活性对于地下水化学特征的形成和演化起着十分重要的作用。将内蒙古河套盆地表层湖相沉积物按10 cm间隔采集,并对沉积有机质的性质及来源进行重点分析。测量了不同深度上不同岩性沉积物的色度、水溶性有机物（WEOM）和盐溶性有机物（SEOM）含量及其光谱学特性。结果显示,沉积物的色度（R530-520）与TOC含量呈现相反的变化趋势:色度值较大时,TOC含量反而较小。相对于细砂层,黏土层的色度值较低,但TOC含量较高。相同的沉积物中,SEOM含量高于WEOM,但WEOM更易迁移至地下水中。有机物的光谱指数表明,WEOM以微生物来源为主,而SEOM以陆源为主。通过三维荧光光谱分析发现,荧光强度和沉积物有机碳（SOC）含量呈正相关;黏土层沉积有机物荧光强度更高;WEOM和SEOM均含类腐殖质成分和类蛋白成分,但SEOM中腐殖质成分较高;类腐殖质是所研究的沉积物中OM最主要的存在形式。     

韩城区块构造煤类型及其产出煤粉特征分析

构造煤的发育是产生煤粉的关键,破碎后煤岩会产生固有煤粉,而疏松的结构会使得煤岩更容易受钻井、压裂和排采等工程扰动影响,进而产生更多的煤粉。韩城区块经历多期构造,断裂构造造成的煤岩脆性变形、褶皱拉伸与挤压造成的煤岩韧性变形导致构造煤发育。以采集煤样宏观特征差异划分煤体结构类型,运用测井解释识别不同煤体结构类型煤,从纵向和横向上总结区块煤体结构分布规律,并揭示不同煤体结构类型对产出煤粉形态、浓度、粒度特征的影响。     

莺歌海盆地构造演化与强烈沉降机制的分析和模拟

莺歌海盆地新生代发生了快速沉降, 盆内充填了最厚达17 km的沉积, 根据模拟实验, 印支地块或之上刚性地块的存在对莺歌海盆地的强烈沉降具有重要的贡献, 可能是造成莺歌海盆地裂陷期强烈沉降的重要原因之一.结合地质分析和物理模拟实验, 莺歌海盆地的演化大致可以分为以下4个主要阶段: 早期(42 Ma以前) 主要受到南海北部陆缘(主要是北部湾盆地) 裂解造成的右旋转换伸展作用的影响, 但影响范围较小, 主要为莺歌海盆地西北部和东部边界.42~21 Ma期间, 主要受控于印支地块左行走滑和顺时针旋转作用的影响, 莺歌海盆地在此期间发育了主体裂陷体系, 东侧受到右旋转换伸展应力场的叠加影响而导致沉降加强; 21~10.4 Ma期间, 受印支地块逐渐减弱直至停止的左行走滑作用的影响, 盆地西北部在21~15.5 Ma期间发生局部反转褶皱, 但盆地整体进入以热沉降为主的时期; 10.4 Ma以后, 盆地受华南地块沿红河断裂右旋走滑作用和5 Ma以后新一期热事件的影响.      

氟碳钙铈矿的42R、48R的16H新多型

采用CM12透射电镜,对我国四川昌北M稀土矿床中的氟碳钙铈矿微结构特征作了电子衍射分析和晶格象观察,揭示出氟碳钙铈矿晶体中混合多型体的堆垛序列,在不同部分观测到不同的多型体,其中以氟碳钙铈矿6R多型为常见普通多型体。本次工作发现了42R、48R和16H三种新多型,并进一步证明,氟碳钙铈矿晶体中存在的多型结构相当复杂,但以长周期堆垛形成的多型体出现的几率要比短周期堆垛的多型体少得多。     

东天山秋格明塔什-黄山韧性剪切带特征与成矿综述

东天山"秋格明塔什-黄山韧性剪切带"是一条多期活动且持续时间很长的韧性剪切变形变质带,介于北部的康古尔塔格-黄山断裂和南部的雅满苏-苦水断裂之间。在研究其空间展布特征、变形组构、演化序列、力学性质、剪切位移量以及变形时代的基础上,对其与成矿的关系进行了初步探讨。     

准噶尔盆地西北缘布龙果尔凹陷构造变形特征解析

布龙果尔地区位于谢米斯台与沙尔布尔提褶皱造山带的交汇部位,该区构造复杂,至今仍属于研究的空白区域.此次在1∶200000和1∶50000地质图及地质报告的基础上,结合野外实地构造考察,对区内的构造发育特征进行了详细的分析研究.强烈的构造运动导致区内不整合发育,根据这些不整合,可以将研究区中泥盆统—第三系地层划分为6个主...     

SHRIMP zircon U-Pb dating of the intrusives in the Tongling metallogenic cluster and its dynamic setting

This paper selected five typical Mesozoic intrusives from the Tongling metallogenic cluster (Xiaotongguanshan, Fenghuangshan, Xinqiao, Dongguashan, and Shatanjiao plutons), and made a systemic SHRIMP zircon U-Pb dating for the five plutons, which produced an age range of 151.8±2.6- 142.8±1.8 Ma. This work put an accurate constraint on the formation age of the intrusives in the Tongling metallogenic cluster. These age data indicate that magmatic activity reached a peak during Late Jurassic. The intrusive sequence of magma is generally from quartz monzonite (porphyry) through monzonite to granodiorite to quartz monzodiorite to pyroxene monzodiorite to gabbro-diabase. The intrusives of different lithology differed in crystallization age, probably implying the intrusives in the Tongling area underwent an evolutional process of magma, which was closely related to geodynamical setting in the depths of the area. A dynamic model was presented for the origin of the igneous rocks in the study area as follows. The assembly between the Yangtze craton and the North China craton fini- shed at the end of T3, and then the stage of another compressional orogeny began in the Tongling area, i.e., Pacific dynamic system. Along with the subduction of the Izanagi plate underneath the Eurasian plate at J2-J3, NW-trending compression toward the East China continent was produced, and compres- sional deformation also took place, forming NE-trending fold and resulting in thickening of the crust in the Tongling area. High-density eclogite-facies rocks were produced in the low part of the crust, re- sulting in the delamination of mantle lithosphere and lower crust, and upwelling of materials in as- thenosphere. Decompression melting produced basaltic magma, and the materials in lower crust were heated by the underplating of the basaltic magma. Thus, melting of lower crust yielded granitic magma, which intruded along deep and large faults through various geological processes (J3-K1). The SHRIMP U-Pb zircon age of 151.8±2.6-142.8±1.8 Ma for intrusives in the Tongling area suggests that the de- lamination of lithosphere mantle and lower crust at least began at middle-late stage of Late Jurassic, resulting in sharp thinning of lithosphere and intense extension of middle-upper crust. Thus, a lot of decollements were produced between cover and cover, basement and cover, and middle and lower crust. This was structural layering or detachment of lithosphere in the Tongling area. Three concordant ages for old inherited cores of magmatic origin (747-823 Ma) indicated that there were obvious mag- matism in the Tongling area during Neoproterozoic, and a little more of the Neoproterozoic igneous source rocks participated in the formation of Mesozoic intrusives.     

应用GPS数据和Slepian基函数反演川云渝地区陆地水储量变化

局部Slepian函数是将局部区域内的地球物理信号转化为空间谱的一种方法,其可以保证在球面上局部范围内获得最优谱平滑解,非常适用于局部范围地球物理信号的研究.本文利用中国陆态网西南地区72 个测站的连续GPS观测资料分析川云渝地区陆地水负荷形变特征,并基于Slepian函数方法解算 60 阶的空间谱基函数,结合弹性质量...     

新疆东天山黑白山镁铁超镁铁岩地球化学、U-Pb年代学、Hf同位素特征及地质意义

黑白山镁铁超镁铁岩位于新疆中天山地块与觉罗塔格构造带的分界断裂——阿其克库都克大断裂南侧约4 km处.该岩体主要由阳起石化橄榄辉石岩、辉橄岩、辉石岩、蚀变细粒辉长岩组成,对岩体的主微量及稀土元素地球化学特征研究表明,岩体属铁质镁铁超镁铁岩,具低钾拉斑玄武质岩的分异特征;岩石具相对较低SiO2(43.90％～52.80％...