Chronology, Geochemistry and Tectonic Settings of the Hadamiao Granodiorite on the Northern Margin of the North China Platform     

HAO Baiwu 《《地质学报》英文版》2010,84(6):1500-1513

<正>The Hadamiao granodiorite,located on the northern margin of the North China platform and acting as the country rock of gold deposits in the Hadamiao region,was formed in the same age and similar tectonic settings with the Hadamiao gold deposit and the large-scale Bilihe gold deposit in the same area.By using the LA-ICP-MS method,the U-Pb age obtained is 267±1.3 Ma,which represents the crystallized age of the granodiorite,and that of the xenolithic zircon is 442.8±5 Ma. Base on the main elements,it exhibits the features of calc-alkaline to high-potassium calc-alkaline series,low silicon,and quasi-aluminous I-type granites,and with high magnesium(Mg~#=0.45-0.57) and high sodium contents(Na_2O/K_2O=0.98-2.29).The SREE values(81.6-110.15 ppm) are relatively low,the fractionations between LREE and HREE are obvious,showing a right-inclined dispersion in the REE distribution diagram.Compared with the primitive mantle,the rock is relatively rich in LREE(La and Ce),LILE(K,Sr,and Th),and intensively depleted in HFSE(Ti,P,Nb and Ta).The ratios of Sr/Y and(La/Yb)_N and the contents of Rb,Nb and Y are relatively low,the Sr values are high (436.35-567.26 ppm),and the Yb contents of most samples are low(1.25-1.8),which indicate the features of typical continental margin arc and adakitic rocks.According to the values ofε_(Nd)(t)(-2.4 to +0.2) and I_(Sr)(0.7028-0.7083),and variations of the La/Sm ratios,the Hadamiao granodiorite was formed from mixing of the thickened molten lower crust and the mantle wedge substances.The rock was related to the southward subduction and accretion of the Paleo-Asia Ocean in the Late Paleozoic, being Late Paleozoic magma of the continental margin arc formed on the basement of the Early Paleozoic accretion complexes,and showing a trend of turning into adakitic rocks,which indicates their great metallogenic(Au) potential.  相似文献   

Origin of Paleofluids in Dabashan Foreland Thrust Belt:Geochemical Evidence of 13C,18O and 87Sr/86Sr in Veins and Host Rocks     

Zeng Jianhui  Xu Tianwu  Sun Zhanqiang  Zhang Yongwang 《《地质学报》英文版》2010,84(5):1239-1255

In the last ten years, with important discoveries from oil and gas exploration in the Dabashan foreland depression belt in the borderland between Shanxi and Sichuan provinces, the relationship between the formation and evolution of, and hydrocarbon accumulation in, this foreland thrust belt from the viewpoint of basin and oil and gas exploration has been studied. At the same time, there has been little research on the origin of fluids within the belt. Based on geochemical system analysis including Z values denoting salinity and research on δ13C, δ18O and 87Sr/86Sr isotopes in the host rocks and veins, the origin of paleofluids in the foreland thrust belt is considered. There are four principal kinds of paleofluid, including deep mantle-derived, sedimentary, mixed and meteoric. For the deep mantle-derived fluid, the δ13C is generally less than ?5.0‰PDB, δ18O less than -10.0‰PDB, Z value less than 110 and 87Sr/86Sr less than 0.70600; the sedimentary fluid is mainly marine carbonate-derived, with the δ13C generally more than ?2.0‰PDB, δ18O less than ?10.0‰PDB, Z value more than 120 and 87Sr/86Sr ranging from 0.70800 to 0.71000; the mixed fluid consists mainly of marine carbonate fluid (including possibly a little mantle-derived fluid or meteoric water), with the δ13C generally ranging from ?2.0‰ to ?8.0‰PDB, δ18O from ?10.0‰ to ?18.0‰ PDB, Z value from 105 to 120 and 87Sr/86Sr from 0.70800 to 0.71000; the atmospheric fluid consists mainly of meteoric water, with the δ13C generally ranging from 0.0‰ to ?10.0‰PDB, δ18O less than ?8.0‰PDB, Z value less than 110 and 87Sr/86Sr more than 0.71000. The Chengkou fault belt encompasses the most complex origins, including all four types of paleofluid; the Zhenba and Pingba fault belts and stable areas contain a simple paleofluid mainly of sedimentary type; the Jimingsi fault belt contains mainly sedimentary and mixed fluids, both consisting of sedimentary fluid and meteoric water. Jurassic rocks of the foreland depression belt contain mainly meteoric fluid.  相似文献   

深穿透化探方法及在矿产勘查中的应用          下载免费PDF全文

赵洪涛  张庆华 《地质找矿论丛》2010,25(3):196-200,211

文章简述了深穿透化探方法的基本理论,介绍了地气测量方法、活动态金属离子法、金属元素活动态提取法和电地球化学法4种深穿透化探方法,并对深穿透化探方法的应用现状及其地质效能进行了评析,指出在应用综合勘查技术和化探异常信息时需要注意与工作区的成矿地质条件相结合。  相似文献   

四川阿坝地区刷马金矿床地质地球化学特征及成因探讨     

秦兵  朱汇派  唐文春 《大地构造与成矿学》2010,34(2)

通过对刷马地区地质构造、矿床时空演化以及水系沉积物、土壤、岩石地球化学特征的综合研究,结合地质背景和区域地质环境,认为刷马地区金矿床赋存于上三叠统侏倭组变质石英砂岩中,严格受北西向的韧-脆性剪切带控制,与金矿化有关的蚀变主要有黄铁矿化、硅化、碳酸盐化、毒砂化和黄铜矿化,1∶20万、1∶5万水系沉积物和1∶1万土壤均显示有Au、As、Sb、Hg的地球化学组合异常,1∶20万水系沉积物异常显示Au矿矿田范围,1∶5万水系沉积物异常显示矿区位置,而1∶1万土壤异常与矿体展布基本一致,异常带稳定连续、规模大,异常展布受控于韧-脆性剪切带,是有利的Au成矿区,具有巨大的找矿潜力,其矿床类型初步判定为微细浸染型金矿床(卡林型金矿)。  相似文献   

攀枝花市大气降尘的地球化学特征     

蒋实  张成江  徐争启  徐进勇 《物探化探计算技术》2010,32(1):84-89

运用ICP-MS和ICP-OES分析了攀枝花市不同时段不同地点大气降尘中重金属元素含量,并对大气降尘中重金属的地球化学特征进行了分析,得出以下结论:①攀枝花市大气尘中As、Co、Mn、Pb、Ti、V的含量,与四川省其他城市相比均偏高,Zn的含量相对较低;②Cd、Mn、Pb主要分布在冶炼区和石灰石矿区,Co、Cu、Ti主要分布在石灰石矿区,Cr和V主要分布在冶炼区,As在仁和河富集较为富集,Zn集中在排土场附近,Fe集中在冶炼区和煤矿区;③除Pb外,其余十种元素旱季含量基本都高于雨季,而雨季Pb的含量却明显高于旱季。通过主成份分析,得出了在攀枝花市大气降尘中,重金属元素的来源主要为矿山污染和开采过程中产生的废水、废气。  相似文献   

沉积特征对砂岩型铀成矿类型的制约——以松辽盆地南部姚家组为例     

马汉峰  罗毅  李子颖  于振清 《国外铀金地质》2010,(1):6-10,61

不同沉积体系砂体的特征不同,在后生铀成矿过程中所起的作用也不同。通过对松辽盆地南部姚家组地层沉积特征的研究,提出沉积特征对铀成矿类型有制约作用;上白垩统姚家组沉积体系以冲积平原、辫状河、三角洲和湖泊等为主,形成了稳定的泥-砂-泥地层结构,受沉积体系的控制,该区砂体厚度稳定、分布范围广,是松辽盆地南部寻找层间氧化带型铀矿的找矿有利目的层。  相似文献   

区域地下水演化的地球化学研究进展   总被引：10，自引：0，他引：10       下载免费PDF全文

滕彦国  左锐  王金生  林学钰 《水科学进展》2010,21(1):127-136

由于区域地质特征、水文地质条件、气候影响和人类活动的差异性,导致区域地下水演化的地球化学过程复杂、影响因素众多.在总结近年来国内外区域地下水化学演化研究大量成果的基础上,综述了地下水演化的地球化学系统分析方法,地下水演化研究的水文地球化学方法、同位素地球化学和元素地球化学方法和技术以及地下水演化的地球化学模拟方法和技术及常用软件.指出在今后的一段时期内,区域地下水自然演化与人类活动的复合作用、地下水与地表水的相互作用、微生物-水-岩相互作用将是区域地下水地球化学研究的热点领域,其中物理、化学、生物的耦合作用将是区域地下水演化的地球化学研究的重点领域.  相似文献   

REE and Sr-Nd Isotope Geochemistry for Yixian Fluorite Deposit,Western Liaoning Province,China,and Its Geological Implications     

孙祥  邓军  杨立强  王庆飞  杨子荣  龚庆杰  王长明 《中国地质大学学报(英文版)》2010,(2)

Up to now,there were no systematic studies of geochemistry and isotopic age for the Yixian(义县) fluorite deposit,western Liaoning(辽宁) Province,China.Based on the analysis of metallogenic geological setting,we studied the REE,Rb-Sr and Sm-Nd isotopes.The chondrite-normalized REE patterns of fluorite are characterized by moderate LREE depletion(LREE/HREE=0.95-3.57,(La/Yb)N=0.08-2.84) and enrichment of Sr(146×10-6-596×10-6) and moderately positive Eu anomalies(δEu=1.10-1.34),which are similar to those of the ho...  相似文献   

新疆哈密图拉尔根Ni-Cu硫化物矿床成矿模式研究          下载免费PDF全文

刘壮  汤中立 《甘肃地质》2010,(3):1-8

新疆图拉尔根Ni-Cu硫化物矿床产于康古儿塔格—黄山韧性剪切带的北东段,属于岩浆熔离贯入型矿床。1号岩体以全岩矿化为特征,各岩相环带状产出,岩性具有单期岩浆多次脉动上涌成矿特征。由大地电磁测深剖面图、稀土元素配分曲线和微量元素可知1号和2号岩体具有同源性,并具有互补性,在深部具有同一个岩浆通道。较低的La/Sm(2)和Th/Ta值(4.6)表明成矿岩浆为地幔来源,岩体就位时很少受到地壳的混染。PGE特征表明,图拉尔根岩浆源于地幔低程度的部分熔融。Pd-Ni图显示在岩浆演化早期没有发生过硫化物的熔离作用。根据岩石学、岩相学、地球化学等资料综合分析,对图拉尔根Ni-Cu硫化物矿床的成矿模式进行了探讨,认为其成矿模式为深部熔离反相复式贯入成矿。构造在图拉尔根矿床就位过程中起了重要影响,决定了矿体的产出状态。  相似文献   

松辽盆地东部湖湾环境的识别及意义     

赵志平  万晓樵  席党鹏  司伟民  李顺  荆夏 《世界地质》2010,29(2):262-270

通过对宾县鸟河乡鸟河剖面和红石山剖面的沉积学分析,结合古生物、地球化学和古地理位置等资料,初步恢复了当时的古环境特征。鸟河剖面以灰绿色泥岩为主,夹有黄铁矿和白云岩结核层,属于湖湾环境沉积;红石山剖面下部以绿色泥岩为主,中上部变为以红色泥岩为主的沉积,早期属滨浅湖环境,之后水体变浅逐步转为泥坪相沉积。当物源不充足时,沉积物以泥岩为主,发育水平层理,化石种类少但成层性好,泥岩中常夹有白云岩和黄铁矿层。湖湾从湖盆断裂坳陷开始,经水体加深接受沉积,水流波浪侵蚀破坏湖底及湖岸阻隔,后水体逐步变浅,最终转化为泥沼。  相似文献