南岭西段加里东期苗儿山岩体锆石SHRIMPU-Pb年龄、地球化学特征及其构造意义

苗儿山岩体位于南岭西段,主体为加里东期花岗岩,少量印支期和早燕山期花岗岩。加里东期花岗岩具块状构造,由早期黑云母花岗闪长岩、中期斑状黑云母二长花岗岩和晚期细粒黑(二)云母二长花岗岩组成,以斑状黑云母二长花岗岩为主。对中期斑状黑云母二长花岗岩和晚期细粒二云母二长花岗岩各进行了1个样品的锆石SHRIMP U-Pb年龄测试,分别得到428.5±3.8 Ma、409±4 Ma的年龄值,反映出早志留世末、志留纪末-泥盆纪初2期岩浆事件。中期主体花岗岩具有富硅(SiO2=70.09%~76.59%)、中铝(Al2O3=12.71%~14.72%)、高钾(K2O=4.48%~5.73%)、中碱(Na2O+K2O=7.24%~7.91%)、高ASI(平均1.15)的特点,总体属高钾钙碱性系列过铝质花岗岩类。主体花岗岩微量元素中Ba、Nb、Sr、P、Ti表现为明显亏损,Rb、(Th+U+K)、(La+Ce)、Nd、(Zr+Hf+Sm)、(Y+Yb+Lu)等则相对富集,稀土总量中等(179.8×10-6~270.6×10-6),轻稀土富集[(La/Yb)N=5.07~14.33],具明显的负Eu异常(δEu=0.15~0.46)。岩体具有较高的ISr值(0.70660~0.72082)和较低的εNd(t)值(-8.29~-7.94),两阶段Nd模式年龄(t2DM)为1.81~1.84 Ga。C/MF-A/MF图解显示源岩为变质泥质岩和碎屑岩。上述地球化学特征表明花岗岩为S型花岗岩,源岩主要为中、上地壳岩石。花岗岩氧化物和微量元素构造环境判别图解指示岩体形成于后碰撞构造环境。基于岩石成因、构造环境判别以及区域构造演化过程,推断加里东期苗儿山花岗岩的具体形成机制为:在陆内强挤压之后挤压应力相对松弛、压力降低的后碰撞构造环境下,因地壳增厚而升温的中、上地壳岩石减压熔融并向上侵位。结合区域资料分析,苗儿山地区在奥陶纪末-志留纪初北流运动和志留纪后期的广西运动中均产生过强烈的陆内挤压和地壳增厚。     

陕西小秦岭地区熊耳群火山岩型铁(钛)矿及资源潜力

对小秦岭地区熊耳群地层的分布作了概述。在熊耳群地层分布区划出了坝源—洛源(A区)、三岔—石门(B区)和西峪河—梧桐河(C区)三个火山岩型铁矿资源潜力区。阐述了各潜力区的铁矿成矿条件,对潜在资源量作了测算。预测全区300 m以上铁矿潜在资源量为≥9.4亿吨,钛铁矿≥300万吨。     

Influence of underground space development mode on the groundwater flow field in Xiong’an new area

The degree and scale of underground space development are growing with the continuous advancement of urbanization in China. The lack of research on the change of the groundwater flow field before and after the development of underground space has led to various problems in the process of underground space development and operation. This paper took the key development zone of the Xiong’an New Area as the study area, and used the Groundwater modeling system software (GMS) to analyse the influence on the groundwater flow field under the point, line, and surface development modes. The main results showed that the underground space development would lead to the expansion and deepening of the cone of depression in the aquifer. The groundwater level on the upstream face of the underground structure would rise, while the water level on the downstream face would drop. The “line” concurrent development has the least impact on the groundwater flow field, and the maximum rise of water level on the upstream side of the underground structure is expected to be approximately 3.05 m. The “surface” development has the greatest impact on the groundwater flow field, and the maximum rise of water level is expected to be 7.17 m.     

河南嵩县南部熊耳群古火山构造与成矿关系研究

河南嵩县南部熊耳群古火山构造保存完整,喷发旋回清晰,火山岩相及爆发相主要岩石种类齐全。其主要喷发类型为裂隙式喷发,次为中心式喷发,主要受区域基底断裂控制,且沿区域切壳深大断裂带呈串珠状分布。表明基底断裂一火山喷发带一区域断裂带是一个连续发展的过程。区内金及部分有色金属矿产与熊耳群古火山活动密切关联,古火山口爆发角砾岩产出地段是寻找该类型金矿的最佳地段,受古火山构造控制的古火山口及其周边的中性、酸性次火山岩脉（墙）,是寻找钼、金、铅锌多金属矿产的有利部位。     

小秦岭—熊耳山地区燕山期大规模成矿的地球动力学背景

基于小秦岭-熊耳山地区多金属矿床辉钼矿Re-Os模式年龄、矿物40Ar-39Ar年龄、高精度矿物和岩石Rb-Sr等时线测年数据,以及与成矿相关花岗岩的SHRIMP测年数据的分析和研究,认为小秦岭-熊耳山地区燕山期大规模成矿作用主要出现在140Ma和120 Ma两个时期,其中钼钨铅锌矿系列主要形成于早成矿期,金矿形成于晚成矿期.根据与这两个成矿期所对应的岩浆热事件,说明是两期岩浆活动的结果, 其所对应的地球动力学背景分别为构造体制大转换和岩石圈大规模拆沉作用下的伸展环境.     

The Palaeomagnetic Study of the MineralizationAge of Gold Deposits in the Xiong'' ershan Area,Henan Province

Based on palaeomagnetic studies of the Precambrian gold deposits in the Xiong'ershan area, Henan Province, the authors infer that the ore-forming processes of the Beiling alteration-type gold ore deposit and the Dianfang breccia-type gold ore deposit started in the Proterozoic, and was superimposed by later mineralization, whereas the mineralization age of the Jiguanshan quartz- vein type gold ore deposit is Yanshanian.     

Hydrogeochemical characteristics of groundwater and pore-water and the paleoenvironmental evolution in the past 3.10 Ma in the Xiong’an New Area,North China

The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area, North China, which caused the enhanced mixing of groundwater in different aquifers and significant changes in regional groundwater chemistry characteristics. In this study, groundwater and sediment pore-water in drilling cores obtained from a 600 m borehole were investigated to evaluate hydrogeochemical processes in shallow and deep aquifers and paleo-environmental evolution in the past ca. 3.10 Ma. Results showed that there was no obvious change overall in chemical composition along the direction of groundwater runoff, but different hydrochemical processes occurred in shallow and deep groundwater in the vertical direction. Shallow groundwater (< 150 m) in the Xiong’an New Area was characterized by high salinity (TDS > 1000 mg/L) and high concentrations of Mn and Fe, while deep groundwater had better water quality with lower salinity. The high TDS values mostly occurred in aquifers with depth < 70 m and >500 m below land surface. Water isotopes showed that aquifer pore-water mostly originated from meteoric water under the influence of evaporation, and aquitard pore-water belonged to Paleo meteoric water. In addition, the evolution of the paleoclimate since 3.10 Ma BP was reconstructed, and four climate periods were determined by the δ¹⁸O profiles of pore-water and sporopollen records from sediments at different depths. It can be inferred that the Quaternary Pleistocene (0.78–2.58 Ma BP) was dominated by the cold and dry climate of the glacial period, with three interglacial intervals of warm and humid climate. What’s more, this study demonstrates the possibilities of the applications of pore-water on the hydrogeochemical study and further supports the finding that pore-water could retain the feature of paleo-sedimentary water.© 2021 China Geology Editorial Office.     

豫西熊耳群火山岩中杏仁体研究及其意义

河南豫西中元古界熊耳群火山岩系广泛分布,且遭受多次构造活动、岩浆侵入及剥蚀的影响。区域火山活动贯穿整个中元古代熊耳期,时间自NE向SW由早到晚。通过对熊耳群火山岩的岩石学研究,确定了熊耳群的岩石系列及火山岩中的杏仁体,通过对其中杏仁体分布、形状及内部构造的研究,可为今后有找矿勘查打好基础。     

Ore-controlling Geological Factors of Gold Deposits in the Xiong＇ ershan Region, Western Henan Province

本文统计了豫西熊耳山地区53个金矿床（点）,编绘了熊耳山地区金矿床分布图。系统的野外矿床地质观察以及熊耳山地区矿床分布图都显示,该区金矿的主要控矿要素为太华群变质结晶基底、北西向和北东向断裂构造,以及燕山期酸性侵入岩。太华群处于熊耳山核部,南北两侧以不整合接触带分别与熊耳群及新生代地层相拆离。矿集区45％的金矿床分布于太华群内,从鲁山、熊耳山到小秦岭．金矿化程度增强,而太华群中的金丰度依次降底,显示太华群提供了部分成矿物质。近东西向马超营断裂为熊耳山地区一级构造单元,其北侧发育一系列北东向次级断层。区内金矿床主要分布于马超营断裂以北,明显沿北东向断层成带分布,且矿床的控矿构造也呈北东向,暗示了北东向断层的控矿特征。研究区内发育有花山、五丈山、合峪、太山庙等大花岗岩体和大量石英斑岩脉和花岗斑岩岩脉。花山岩体和五丈山岩体与地层外接触带是控制金矿床产出重要区域,36％的金矿床产出于岩体附近或角砾岩体内,小型岩脉则广泛发育于各金矿床内。本区1：20万区域化探金含量存在七个异常区,分别与该区金矿床集中分布区相吻合。