湘西花垣MVT型铅锌矿的资源储量巨大,成矿前景好.研究区内层状藻灰岩相是主要预测方向,矿化角砾岩是进一步找矿的重要标志,但是如何判别层状角砾岩的含矿特征尚需深入研究.通过对花垣铅锌矿进行研究,探讨角砾岩成矿过程,分析不同成矿阶段角砾岩的地质特征,根据对角砾和胶结物的观测与分析,划分了不同矿化阶段的角砾岩.①成矿前角砾岩:该类角砾岩不含矿,其中角砾与胶结物均无矿化现象出现,以似层状和条纹状角砾岩为主要类型;②成矿期角砾岩:该类角砾中含矿,其中角砾与胶结物均出现明显的矿化现象,以网脉状含矿角砾岩、斑脉状含矿角砾岩、细脉状含矿角砾岩和侵染状含矿角砾岩为主要类型;③成矿后角砾岩:该类角砾岩含少量矿化,其中角砾多有矿化现象,而胶结物无矿化或较弱矿化,以不规则网脉状角砾岩为主.角砾岩矿化阶段的判别对于构造岩相地质找矿及成矿规律研究,具有重要的参考价值.

湘西花垣铅锌矿田发育典型的层控型铅锌矿床,找矿潜力巨大.该区在矿床成因、控矿因素等方面存在不同认识,主要观点有密西西比河谷型、沉积型、成岩期后改造型和盆源低温热液型4种观点.通过构造测量解析和古应力场恢复,分析了构造与成矿的关系,划分出成矿前构造主压应力近似垂直层面,成矿期构造主压应力方向为北西—北北西,成矿后构造主压应力方向为北东—北北东向;成矿期构造形成了矿田内李梅平缓背斜、渔塘背斜,并在藻灰岩层内形成各类含矿角砾岩、裂隙系统,这些裂隙为热液与藻灰岩中富含的有机质发生化学反应提供了丰富的反应界面,是铅锌矿液富集的主要原因.成矿后构造主要形成于燕山期,受北北东—南南西向挤压应力作用,形成了北东走向的大型走滑正断裂带,对加里东期成矿期赋矿褶皱造成破坏改造.

The Jiaodong gold mine has a world-class large gold deposit.Different from the greenstone-belt type gold mine,it contains ore-forming anatexis granite of crust origin as a result of Mesozoic activation and transformation;and underwent an unique mineralization brought by platform tectono-magrnatic activation.Previous researchers lay emphasis on the study of plate subduction and orogeny,but here they also need to consider the intra-continental tectonic environment and magmatic intrusion,as well as the special process of the late stress-relaxation induced hydrothermal metasomatic metallogenesis of Jiaodong gold deposit.Selecting five 1 ∶ 50000 geological-sections of 220 km in total length,we carried out field observations and completed the 1 ∶ 250000 tectonical lithofacies metallogenic map of the Jiaodong Laizhou-Zhaoyuan region.Here we present the metallogenic model of "mineralization of tectono-magmatic upheaval-hydrothermal alteration in detachment zone".In this model,in the counterclockwise shearing structures of East Asia region,Moho fluctuation induced by the tectonic stress field first brought about the North-East mantlebulge and mantleshrinkage,where Moho distribution controlled the concentrated development zone of Mesozoic metasomatism molten magmaNext,as shown by the diagenetic structural measurement and analysis of granites,the tectonic magmatic dome formed with the Linglong granite body at its core,and regional shear fracture zone developed in the contact zone between metamorphic rocks and granites in Jiaodong groups.In later times,the shear zone developed normal faulting from the sliding of the hanging wall,and a large-scale post-magmatic hydrothermal replacement-alteration occurred at the shear detachment zone,as illustrated by the structural measurement of fracture zone.In the final step,in a 1.5 km wide or wider fractured rock zone,superimposed hydrothermal metasomatic alteration formed the huge Linglong-Jiaojia-type quartz vein-altered rock type gold mine.This new metallogenetic model not only has a role in promoting studies on the metallogenesis of the Jiaodong gold mine,it can also guide the deep peripheral mine explorations.

In order to investigate carbonate rocks during the deposition of ancient environment of instructions,geochemical analysis were taken for limestone and dolomite samples from the Cambrian Qingxudong Formation and lines layered dolomite samples from the Cambrian Gaotai Formation in the periphery of Limei mining area,Xiangxi,China.Results indicate that 1) In carbonates Sr is positively correlated with CaO,Si,A1,and K and Ti is positively correlated with Fe,Si,A1,K,and V,reflecting limited impact on terrigenous matter and diagenesis,during carbonate deposition period from Qingxudong to Gaotai;2) Lower REE content,weak rare earth elements differentiation and the characteristic of a slight enrichment of light rare earth elements relative to heavy rare earth elements,are in accordance with typical characteristics of low content of rare earth elements in marine carbonate rocks;and 3) In the study area,it accords with petrology and geochemical characteristics of elements in the sedimentary environment,so the research on the geochemical characteristics of the rock is beneficial to the recovery of the ancient sedimentary environment and the discrimination and reconstruction of the ancient climate.The characteristic of petrology and geochemistry indicates the significance of marine carbonate sedimentary environment,which is from wet to dry climate change,the warm ancient sea water temperature,and the ancient seawater medium of the oxidation conditions,from Qingxudong stage to Gaotaiin the studies area.

A set of shallow metamorphic slate type of Neoproterozoic Madiyi formation-Cambrian Niuti-tang formation is deposited in the Minle area, western Hunan,which is bedding development,south-east dip and dip angle of 10 °~20 ° . In order to explore original rock characteristics and formation of the tec-tonic environment of shallow metamorphic slate type in this area, this paper adopts the plasma mass spectrum analyzer to test the rare earth elements of the sample. The results show that slate type total REE of rare earth elements、light and heavy rare earth ratio and anomal Eu、Ce are consistent with sedi-mentary rock, which shows the original rock of slate type are similar to sedimentary rock. Through the∑REE-La/Yb diagram and compared with characteristics of rare earth elements with different tecton-ic background of sedimentary rocks,we can draw the protolith of metamorphic slate type is depisitional clastic detritus( volcanic eruption basalt, mudstone and greywacke) , and formation of the tectonic environment is active continental margin.

花垣—茶洞断裂带位于湖南西部,为松桃—大庸深断裂的分支,是松桃—大庸断裂北段的一部分.通过对断裂带两侧的野外基础特征、节理发育处的测量统计、擦痕与共轭节理的应力分析以及断裂带两侧的深部钻孔勘探揭露,得出花垣—茶洞断裂带的活动至少有2个期次:一期为北东向南西向的左行剪切走滑;另一期为断裂带北侧的地层下滑,下滑距离约为550～700 m.

花垣铅锌矿田位于上扬子地块东南缘的湘西北地区,是我国重要的铅锌产地(邓文龙,1985;杨绍祥,2006,2007).笔者通过野外实地勘查,对矿田范围内构造现象进行了测量分析.矿田内断裂主要有茶洞-花垣大断裂及其伴生的小断裂(图1F1),褶皱主要李梅背斜(图1 F2)、太阳山向斜(图1 F3)、渔塘背斜(图1 F4)及其伴生的小型短轴背向斜.

Huayuan lead-zinc ore field in Zhangjiajie of western Hunan, is a large-sized, and the ore bodies algal limestones the margin of the shallow platform in the lower part of the Early Cambrian Qingxudong Formation. The authors expounded the ore-hosting lithology, sedimentary environment and petrographic evolution of Huayuan lead-zinc ore field. According to the metallogenic characteristics of the Huayuan lead-zinc ore field, the formation and evolution of the ore field is divided into the First construction (geological processes), the secondary construction (lithofacies characteristics) and the third-level construction (basic rock unit).