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191.
192.
在前人地质、矿产成果资料的基础上,通过综合分析与野外工程验收发现大坎子金矿。过去地小水井金矿田的成矿规律存在的认识上的差距,故在已知矿床外围找矿末获得突破;因此,有必要系统介绍大坎子金矿已被后来在矿山开发中证实的矿床地质特征与成矿地质条件,目的是借鉴已知矿床(点)成矿规律,开展成矿预测,选准靶区,为取得找矿上的重大突破提供新思路。 相似文献
193.
胶东-朝鲜半岛中生代金成矿作用 总被引:6,自引:2,他引:6
华北克拉通东部与朝鲜半岛相接,是中朝克拉通的重要组成部分。在华北克拉通东部的胶东半岛和朝鲜半岛内皆产出有不同规模的金矿床,并具有显著的地域特色。胶东半岛已发现金矿床(点)近200处,其中三山岛、焦家、新城、玲珑等为世界级金矿,它们为石英脉型和受构造控制的蚀变岩型,成矿时间主要集中在~120Ma,说明金成矿作用是在相当短的时间内,在同一成矿背景下和同一构造-岩浆-流体成矿系统下完成的。成矿流体主要来自幔源岩浆以及幔源岩浆与地壳相互作用产生的地质流体,就位环境与地壳/岩石圈在早白垩世强烈伸展构造变形有关,为克拉通破坏型金矿;与我国辽东相邻的朝鲜半岛北部平安北道等地金矿储量较大,成矿类型与特征辽东五龙金矿类似,为石英脉型矿化,也可能为早白垩世与华北克拉通岩石圈减薄、破坏相关的金矿床;朝鲜半岛南部的韩国金(银)矿床分成侏罗纪中温热液型和白垩纪浅成低温热液型两类,其中侏罗纪热液脉状金矿成矿特征虽与胶东金矿类似,但成矿时代(峰期~160Ma)有显著差异。而白垩纪浅成低温热液型金-银矿化主要发生在100~70Ma,与太平洋板块俯冲作用相关,为典型的环太平洋斑岩-次火山活动有关的浅成低温贱金属成矿系列。胶东和朝鲜半岛金矿床类型、特征及成矿时间的异同,与区域中生代地质演化及地球动力学背景密切相关。 相似文献
194.
The major Ghanaian lode gold deposits are preferentially aligned along the western and eastern contacts of the Kumasi Basin with the Ashanti and Sefwi Belts, respectively. The investigated area of the Abawso small-scale concession, covering the workings of the old Ettadom mine, is situated 3 km west of the lithological contact of the Birimian metavolcanic rocks of the Akropong Belt in the east with the Birimian metasedimentary rocks of the Kumasi Basin in the west. The rocks of the Abawso concession represent a steeply NW-dipping limb of a SE-verging anticline with an axis plunging to the SW. Quartz veining occurs predominantly in the form of en échelon dilatational veins along NNE–SSW-striking shear zones of a few metres width and shows evidence of brittle and ductile deformation. Also stockwork-style quartz veining occurs in the vicinity of the main shaft of the old Ettadom mine. Hydrothermal alteration includes sericitisation, sulphidation and locally carbonatisation. The auriferous quartz veins mainly follow the trend of brittle to ductile deformed quartz veins; however, some occur in stockwork. Fluid inclusion studies reveal a large number of H2O inclusions along intragranular trails in auriferous quartz vein samples, as well as an overall dominance of H2O and H2O-CO2 inclusions over CO2 inclusions. Textural observations and physico-chemical fluid inclusion properties indicate post-entrapment modifications for all quartz vein samples due to grain boundary migration recrystallisation. This process is interpreted to be responsible for the generation of the CO2 inclusions from a H2O-CO2 parent fluid. In comparison with mineralisation at the Ashanti and Prestea deposits, which are characterised by CO2±N2 inclusions, the observed inclusion assemblage may be due to a shallower crustal level of mineralisation, or different degrees and styles of recrystallisation, or a less pronounced development of laminated quartz veins due to comparably restricted pressure fluctuations. Furthermore, the microthermometric observations allow the reconstruction of a possible retrograde P-T path, depicting near-isothermal decompression in the P-T range of the brittle/ductile transition.Editorial handling: E. Frimmel 相似文献
195.
丁耀伟 《华东地质学院学报》1989,(4)
本文探讨了用微型活性碳柱富集痕量金的方法。研究了富集金和TMK—Au—Twee 85显色反应的条件,用本法测定了地质试样中痕量金,其测定限为2 ppbAu,本法操作简便、快速,灵敏度高,结果较为满意。 相似文献
196.
197.
陕西省潼关县碾头岔含金石墨矿工艺矿物学研究 总被引:2,自引:0,他引:2
工艺矿物学系统研究表明:碾头岔含金石墨矿床的矿石中除石墨外,可综合利用的有用元素还有金、铜等。金矿物颗粒较细,主要以独立矿物形式赋存于载体矿物黄铜矿、黄铁矿及石墨中。黄铜矿是主要的铜矿物,其次有蓝辉铜矿。石墨呈独立矿物存在,片大且较平直,属于大鳞片石墨,矿石中总碳仅有65%左右以石墨碳形态存在。上述3种有用元素均可通过合理磨矿,选择适宜的选矿条件得到金精矿、铜精矿和石墨精矿。然而由于石墨精矿中杂质较多且颗粒细小,主要为极细的片状硅酸盐,要得到高品级石墨,用机械选矿办法是无能为力的,需要对精矿进一步加工处理方可奏效。 相似文献
198.
The Picacho gold deposit, located in southeasternmost California, is a low-grade gold deposit in a nearly flat-lying denudational
fault of regional extent and probable Oligocene age. The deposit is hosted by intensely fractured and faulted Mesozoic leucogranite
and by chloritic augen gneiss and schist, and is overlain unconformably and in fault contact by unmineralized late Oligocene
Quechan volcanic rocks. The deposit is structurally characterized by normal and normal-oblique faults of low to high dip at
shallow depths in the mine, merging downward with a synchronous, low-dipping ore-stage extensional fault system (the Chocolate
Mountains/Gatuna Fault) of probable Oligocene age in deeper portions of the deposit. The fault system was infiltrated during
much of its active life by hot, dilute, highly exchanged meteoric water having temperatures of 170°–210° C, salinity <2 wt%
NaCl equivalent and calculated δ18Ofluid between −2.6‰ and 5.2‰. This main-stage fluid precipitated quartz, pyrite, and specular hematite, accompanied by silicification
and sericitization. Auriferous ore-stage pyrite was precipitated late in the fault evolution probably by mixing of reducing
ore fluid with relatively oxidized main-stage fluid during regional Oligocene extension on the Chocolate Mountains/Gatuna
Fault. The Picacho deposit is characterized by a gold–arsenic–antimony geochemical signature consistent with bisulfide complexing
of gold in reducing fluid, in contrast with typical denudation fault-hosted base-metal-rich deposits associated with high-salinity
fluids elsewhere in the southwestern United States. The deposit is overprinted by Miocene normal faults having a wide range
of dips. These postore faults are associated with red earthy hematite precipitation, pyrite oxidation, and supergene enrichment
of gold.
Editorial handling: L. Meinert 相似文献
199.
枣子沟金矿地质特征及成矿模式探讨 总被引:1,自引:0,他引:1
枣子沟金矿位于新堡-力士山复背斜南翼之合作-岷县区域断裂带上,是西秦岭西段近年来勘查的特大型金矿床之一.在研究矿区地质特征基础上,通过对矿体特征、矿石成分、成矿流体主要来源及成矿作用过程等分析研究,提出该矿床成矿模式. 相似文献
200.