东特提斯二叠纪地层,古地理及矿产国际学术讨论会综述     

颜佳新 《地质科技情报》1998,17(1):41-43

概述了“东特提斯二叠纪生物地层、古地理和矿产资源国际学术讨论会（ＰＥＴ）”和“澳大利亚生物古地理国际学术讨论会（ＰＡＦＦ）”所涉及的主要内容及最新研究进展,简要评述了东特提斯地区联合古陆时期的古地理、古气候、古海洋研究现状,指出了我国在该方面存在的差距和今后研究值得注意的方向。  相似文献   

Distribution of potential geological hazards and control factors in Qingdao offshore,China     

《China Geology》2019,2(1):40-48

Engineering construction actively occurs in coastal zones, and these areas have numerous potential geological hazard factors. Since 2009, the development of geological surveys in sea areas has promoted extensive geophysical surveys in Qingdao offshore. In the present study, the types and distribution of potential geological hazard factors were systematically revealed using sub-bottom profile data, side-scan sonar data, and single-channel seismic data, among others. Based on previous research findings, the potential geological hazard factors are classified, and control factors in Qingdao offshore are discussed. The research results show that the primary potential geological hazards include active faults, buried paleo channels, shallow gas, irregular bedrock, eroded gullies, estuary deltas, tidal sand ridges, and seawater intrusion. In addition, neotectonic movement, sea level changes and sedimentary dynamic processes were the main factors that affected the distribution of geological hazards in Qingdao offshore.©2019 China Geology Editorial Office.  相似文献   

中国多阶段活化构造与铀成矿作用     

王木清 《铀矿地质》2017,(1):9-15

中国地质构造和铀成矿复杂,活化构造作用时间长,从早元古宙延续至今,以中新生代最为强烈。针对特定大区域内多种类型铀矿床并存,而主成矿期往往基本一致的特点,笔者从大地构造、深部地质结构、地球物理和地球化学等方面,就中国多阶段活化构造演化及其对铀成矿的控制作用进行了探讨。  相似文献   

Mercury contamination in Long Island Sound, USA, from the historic hat-making industry     

《中国地球化学学报》2006,25(B08):236-237

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Mineralization,Geochemistry and Zircon U‐Pb Ages of the Paodaoling Porphyry Gold Deposit in the Guichi Region,Lower Yangtze Metallogenic Belt,Eastern China   总被引：1，自引：0，他引：1  

DUAN Liu’an  YANG Xiaoyong  DENG Jianghong  WANG Fangyue  LEE Insung 《《地质学报》英文版》2018,92(2):706-732

The newly discovered Paodaoling porphyry Au deposit from the Guichi region, Lower Yangtze River Metallogenic Belt(LYRB), contains 35 tons of Au at an average grade of ~1.7 g/t. It is a porphyry ‘Au-only' deposit, as revealed by current exploration in the depths, mostly above-400 m, which is quite uncommon among coeval porphyry mineralization along the LYRB. Additionally, there are also Cu-Au bearing porphyries and barren alkaline granitoids in the Paodaoling district. Zircon LA-ICP-MS U-Pb dating of the Cu-Au-bearing porphyries yield an age of 141–140 Ma, falling within the main magmatic stage of the LYRB, whereas the barren granites give an age of 125–120 Ma, coeval with the regional Atype granites. The Cu-Au-bearing porphyries are LILE-, LREE-enriched and HFSE-depleted, typical of arc magmatic affinities. The barren granites are HFSE-enriched, with lower LREE/HREE ratios and pronounced negative Eu anomalies. The Cu-Au-bearing porphyries in the Paodaoling district have high oxygen fugacities and high water content. Pyrite sulfur isotopes of the Paodaoling gold deposit indicate a magmatic-sedimentary mixed source for the ore-forming fluids. Based on the alteration and poly-metal zonation of the deepest exploration drill hole from the Paodaoling Au deposit, we propose that Cu ore bodies could lie at depth beneath the current Au ore bodies. The magmatism and associated Cu-Au mineralization of the Paodaoling district are likely to have formed in a subduction setting, during slab rollback of the paleo-Pacific plate.  相似文献   

舟山岛中更新世以来孢粉组合特征及古气候变迁   总被引：4，自引：0，他引：4  

叶兴永 《海洋地质与第四纪地质》2000,20(3):9-13

根据舟山岛ＺＫ１孔３３个孢粉和３７个微体古生物样品的分析,讨论了我国第四大岛－舟山岛自第四纪中更新世以来的古植被,古气候变迁。舟山岛经历了３个寒冷期,２个温暖期和１个冰后期,其中第二冷期又可分出２个亚冷期和２个亚暖期,冰后期可分出北方期－前北方期、亚北方期－大西洋期和亚大西洋期,为舟山岛第四纪地层划分和地层对比提供了充分的依据。  相似文献   

Petrography and geochemistry of upper Triassic sandstones from the Tumengela Formation in the Woruo Mountain area,North Qiangtang Basin,Tibet: Implications for provenance,source area weathering,and tectonic setting   总被引：1，自引：0，他引：1       下载免费PDF全文

Zhongwei Wang  Jian Wang  Xiugen Fu  Xinglei Feng  Dong Wang  Chunyan Song  Wenbin Chen  Shengqiang Zeng 《Island Arc》2017,26(4)

The petrography and major and trace element concentrations of the sandstones from the Tumengela Formation in the Woruo Mountain area, North Qiangtang Basin, are studied to determine their provenance, intensity of weathering and tectonic setting. The detrital compositions of the Tumengela sandstone samples are dominated by quartz (58.0–70.1 %, average 64.7 %) and lithic fragments (21.8–35.9 %, average 27.3 %), but low in feldspar content (4.9–12.9 %, average 8.0 %). The sandstones can be classified as litharenite and feldspathic litharenite according to their detrital compositions, which is consistent with the geochemical data. The detrital modal compositions reflect that these sandstones are probably derived from a recycled orogenic source. The index of chemical variability (ICV) and SiO₂/Al₂O₃ ratio values suggest that the compositional maturity and recycling were moderate. The weathering indices such as the chemical index of alteration (CIA), plagioclase index of alteration (PIA), chemical index of weathering (CIW), and Al₂O₃–(CaO* + Na₂O)–K₂O (A–CN–K) diagram indicate that the intensities of weathering in the source area were moderate. The Al₂O₃/TiO₂, Th/Co, La/Sc, La/Co, Th/Sc, Cr/Th ratio values and the discriminant function of the Tumengela sandstones indicate that the sediments were mainly derived from felsic source rocks, while also mixed with intermediate source rocks. The comparison of rare earth element patterns and its Eu anomalies to the probable source rocks infer that the sandstones were derived from the combination of granite, rhyolite, dacite, and gneisses. The proximal central uplift belt was probably the primary provenance area as evidenced by the petrographical and geochemical features of the Tumengela sandstones. The multidimensional tectonic discrimination diagram based on major elements show a collision setting (80 %) combined with a rift setting (20 %) for the Tumengela sandstones, which is consistent with the general geology of the study areas.  相似文献