福建燕山期高钾钙碱质系列火山岩的地球化学特征岩石成因及构造背景

本文主要从本区火山岩的地球化学特性的分析研究,来探讨火山岩的成因,物质来源,形成时的大地构造环境等问题。通过对岩石化学性质的分析研究结果表明,在岩石化学性质上本区火山岩属高钾钙碱性系列的以英安岩、流纹岩及其相应的碎屑熔岩、熔结凝灰岩为主的造山带的岩石组合类型.对大离子亲石元素中K/Rb比值,稀土元素的总量及LREE/HREE比值(La/Lu)N及Eu/Sm比值的分析研究表明本套火山岩属活动大陆边缘型造山带的岩石组合类型。锶初始值(~(87)Sr/~(86)Sr比值)的研究暗示出本套火山岩组合的岩浆的物质来源在东部沿海地区为幔壳混源型,向西部内陆逐渐变为下部地壳重熔型岩浆.其形成机制与当时太平洋板块向欧亚大陆板块之下俯冲有着内在的成生联系.     

冀北—辽西地区火山次火山热液型金矿地质特征及找矿方向

冀北—辽西地区位处华北准地台北部边缘,燕山期岩浆—火山活动强烈,火山岩分布面积达36200平方公里,火山,尤其次火山热液型金矿的工业意义正在被人们揭示出来。本文根据矿床在火山机构所处的相位,对区内火山、次火山热液型金矿进行了分类,并提出了主攻类型,对其控矿因素、找矿标志和找矿方向进了了客观的总结,最后提出了找矿远景片。已知本区有超浅成、浅成斑岩岩株、岩脉302个,具有可观的找矿潜力。     

五大连池火山地区的某些气体地球化学特征

本文对黑龙江省德都县以北的五大连池火山地区气体和水样进行了质谱分析,以其对该地区内的某些气体地球化学特征进行研究。 一、样品的采集 采用低渗透性的不锈钢和无氧铜管密封的取样器,其体积为250毫升,容器抽成10-5mmHg的真空取水样和气样。样品取得后带回实验室进行气体成分的分析。气体样直接进入质谱计进行成分分析,而水样经脱出气体后再进入质谱计进行分析     

K—Ar Geochronology and Evolution of Cenozoic Volcanic Rocks in Eastrn China

Cenozoic volcanic rocks widespread in eastern China constitute an important part of the circum-Pacific volcanic belt.This paper presents more than 150K-Ar dates and a great deal of petrochemical analysis data from the Cenozoic volcanic rocks distributed in Tengchong,China‘s southeast coast,Shandong,Hebei,Nei Monggol and Northeast China.An integrated study shows that ubiquitous but uneven volcanic activities prevailed from the Eogene to the Holocene,characterized as being multi-eqisodic and multicycled.For example,in the Paleocene(67-58Ma),Eocene(57-37.5Ma),Miocene(22-18,16-19Ma),Pliocene(8-3Ma),and Early Pleistocene-Middle Pleistocene(1.2-0.5Ma) there were upsurges of volcanism,while in the Oligocene there was a repose period.In space,the older Eogene volcanic rocks are distributed within the region or in the central part of the NE-NNE-striking fault depression,while the younger Neogene and Quaternary volcanic rocks are distributed in the eastern and western parts.Petrologically,they belong essentially to tholeiite-series and alkali-series basalts,with alkalinity in the rocks increasing from old to youg.The above regularities are controlled by both global plate movement and regional inherent tectonic pattern.