甘新蒙北山地区成矿带划分和基本特征对比   总被引：3，自引：1，他引：2  

彭巨贵  张发荣  赵福昌 《地球科学与环境学报》2006,28(3):11-18

在对甘新蒙北山地区成矿地质背景和成矿在时空上的联系性等综合研究分析基础上,运用新理论、新认识,以板块构造单元划分为基础,将本区划分为3个Ⅲ级成矿带、11个Ⅳ级成矿带,并对Ⅲ级成矿带特征进行了阐述,以期为矿产勘查和地质大调查工作部署提供新的思路和依据。进一步就主要矿床(点)、构造单元、矿种、赋矿建造、控矿因素、成矿类型、成矿时代等方面进行了对比,认为各Ⅳ级成矿带在区域上具有相对稳定的展布范围,具有相同的构造环境和成矿条件、类似的矿种和成矿时代,存在一定的相似性、可比性,并且各成矿带具有一定的潜在找矿价值。  相似文献   

Proterozoic (pre-Ediacaran) glaciation and the high obliquity,low-latitude ice,strong seasonality (HOLIST) hypothesis: Principles and tests     

《Earth》2008,88(3-4):61-93

Sedimentological observations and palaeomagnetic data for Cryogenian glacial deposits present the climatic paradox of grounded glaciers and in situ cold climate near sea-level, glaciomarine deposition, and accompanying large (up to 40 °C) seasonal changes of temperature, all in low to near-equatorial (< 10°) palaeolatitudes (equated with geographic latitudes). Neither the “snowball Earth” nor the “slushball Earth” hypothesis can account for such strong seasonality near the palaeoequator, which together with findings from sedimentology, chemostratigraphy, biogeochemistry, micropalaeontology, geochronology and climate modelling argue against those scenarios. An alternative explanation of glaciation and strong seasonality in low palaeolatitudes is offered by a high (> 54°) obliquity of the ecliptic, which would render the equator cooler than the poles, on average, and amplify global seasonality. A high obliquity per se would not have been a primary trigger for glaciation, but would have strongly influenced the latitudinal distribution of glaciers. The principle of low-latitude glaciation on a terrestrial planet with high obliquity is validated by theoretical studies and observations of Mars. A high obliquity for the early Earth is a likely outcome of a single giant impact at 4.5 Ga, the widely favoured mechanism for lunar origin. This implies that a high obliquity could have prevailed during most of the Precambrian, controlling the low palaeolatitude of glaciations in the early and late Palaeoproterozoic and Cryogenian. It is postulated that the obliquity changed to < 54° between the termination of the last Cryogenian low-palaeolatitude glaciation at ≤ 635 Ma and the initiation of Late Ordovician–Early Silurian circum-polar glaciation at 445 Ma.The High Obliquity, Low-latitude Ice, STrong seasonality (HOLIST) hypothesis for pre-Ediacaran glaciation emerges favourably from numerous glacial and non-glacial tests. The hypothesis is in accord with such established or implied features of Cryogenian glaciogenic successions as extensive and long-lived open seas, an active hydrological cycle, aridity and palaeowesterly (reversed zonal) winds in low palaeolatitudes, and the apparent diachronism or non-correlation of some low-palaeolatitude glaciations. A pre-Ediacaran high obliquity also offers a viable solution of the faint young Sun paradox of a warm Archaean Earth. Furthermore, reduction of obliquity during the Ediacaran–early Palaeozoic would have yielded a more habitable globe with much reduced seasonal stresses and may have been an important factor influencing the unique evolutionary events of the Ediacaran and Cambrian. The palaeolatitudinal distribution of evaporites cannot discriminate unambiguously between high- and low-obliquity states for the pre-Ediacaran Earth. Intervals of true polar wander such as postulated by others for the Ediacaran and Early Cambrian imply major mass-redistributions within the Earth at those times, which may provide a potential mechanism for reducing the obliquity during the Ediacaran–early Palaeozoic.  相似文献   

西藏马攸木金矿床金银互化物的赋存状态   总被引：3，自引：0，他引：3  

孙燕  温春齐  多吉  霍艳 《地质与勘探》2008,44(5):42-46

马攸木金矿床是西藏近年发现的首例规模较大、矿石品位富、金成色高的岩金矿床.作者通过对马攸木金矿床矿石组构、矿石共生组合及矿物特征研究发现,金银互化物主要有自然金、含银自然金、银金矿、自然银.载金矿物为黝铜矿、针铁矿、脆硫锑铅矿及石英;金银互化物的赋存形式主要为包裹体金、裂隙金及粒间金.金银互化物的形成、富集与热液成矿作用及表生风化作用关系密切.  相似文献   

Helium-argon isotopic tracing for the Pb-Zn-Ag polymetallic ore deposits in the central-south segment of the Da Hinggan Ling Range     

Baode Wang  Shuyin Niu  Aiqun Sun  Huabin Hu  Yaming Liu  Lijun Guo  Shuo Wang 《中国地球化学学报》2008,27(3):235-241

In recent years big strides have been made in the exploration of ores in the central-south segment of the Da Hinggan Ling Range, though some debates still exist on the metallogenesis and sources of ore-forming materials. Pyrite and other sulfides in direct relation to the Pb-Zn-Ag ore deposits were chosen for the He and Ar isotopic analysis of ore-forming fluids, and the first He and Ar isotope data have been obtained from the study region. ^3He/^4He ratios in 14 samples collected from 7 mining districts are 2.17×10^-6-12.52×10^-6, averaging 6.86×10^-6 and their R/Ra ratios are 1.56-9.01 Ra, averaging 4.37 Ra. By projecting the data points onto the ^3He-^4He concentrations diagram, all the points fall near the mantle helium area. The calculated mantle-source helium ratios are within the range of 19.58%-76.96%, with an average of 49.52%. Argon isotopic characteristics are close to those of mantle source, indicating that the ore-forming material was transport upwards via the multi-stage evolution of mantle plume and concentrated as ores in the favorable loci of mantle branch structures.  相似文献   

云南绿春咪霞金矿成矿地质条件   总被引：1，自引：0，他引：1  

普玉斌  杨玉华 《云南地质》2008,27(3):325-330

咪霞金矿赋存在多元素高背景值下志留统薄层状蚀变板岩中,受北西向F6-1断裂及正长岩、煌斑岩控制,与多元素异常、黄铁矿化等多种围岩蚀变对应,具较好的成矿地质条件。  相似文献   

对北秦岭太阳寺矿集区金矿成矿特征的初步认识   总被引：1，自引：0，他引：1       下载免费PDF全文

胡晓隆  赵利利 《甘肃地质》2008,17(1):41-46

甘肃省天水冯家场—两当太阳寺一带,是近年来资源评价和矿产勘查的重点,是秦岭-大别成矿省北秦岭成矿带中重要的矿化集中区。文章在分析区域构造背景的基础上,对该区成矿特征进行了初步总结,选择典型矿床进行了介绍,初次把该区命名为太阳寺矿集区,这将对该区矿产勘查工作部署,深入研究矿集区成矿规律具有参考意义。  相似文献   

北祁连中段浪力克—牛头山一带地球化学特征          下载免费PDF全文

杨文敏  张本旗  张铖 《甘肃地质》2008,(2):35-39

近年来,部署在重要成矿区带的1：5万区域矿产调查在全国陆续展开,这对提高地质矿产研究程度,进一步圈定找矿靶区具有重要意义。其中要求进行1：5万水系沉积物测量、高精度地面磁测、自然重砂测量和遥感异常提取。本文以甘青交界的浪力克一牛头山一带1：5万区域矿产调查中水系沉积物测量实际资料为依据,探讨了浪力克铜矿区及其区域地球化学特征,认为Cu、Pb、Zn、Au、Ag异常分布与含铜火山岩系分布一致,异常规模显示该矿外围仍具有较大的找矿潜力。  相似文献   

甘肃北山印支燕山期花岗岩成矿作用与找矿工作再研究   总被引：2，自引：0，他引：2       下载免费PDF全文

殷先明 《甘肃地质》2008,(3):1-5,35

本文讨论了甘肃北山地区印支燕山期花岗岩的空间分布与构造,矿化集中区的耦合关系;与印支燕山期花岗岩活动有成因关系的几个典型矿床;印支燕山期作用强度、构造环境、矿源层和矿化集中区。  相似文献   

河西走廊疏勒河流域地质灾害危险性现状评估方法的应用——以甘肃省河西走廊(疏勒河)农业灌溉暨移民安置综合开发建设项目8个移民社区及配套工程建设为例          下载免费PDF全文

王永斌  崔艳荣 《甘肃地质》2008,(4):67-71

依据“建设用地地质灾害危险性评估技术要求”、利用野外踏勘及相关资料,对“甘肃省河西走廊（疏勒河）农业灌溉暨移民安置综合开发建设项目8个移民社区及配套工程”进行地质灾害危险性现状评估。结果认为：评估区发育和分布的地质灾害类型有土壤盐渍化、风蚀沙埋和洪水冲蚀。现状评估结果：土壤盐渍化和洪水冲蚀危险性均小;风蚀沙埋有1处危险性中等,其它危险性小。  相似文献   

河南石板沟金矿矿床地质特征及成因探讨     

苏小岩 《华南地质与矿产》2008,(2):20-25

在总结石板沟金矿床矿化地质特征的基础上,通过对矿石氢氧同位素测试和矿石微量元素相关分析,认为成矿热液主要来源于变质水,矿床成矿环境应属低温环境,矿床成因类型属受构造剪切带控制的低温变质热液蚀变型金矿床。  相似文献