地质科技通报2025，Vol.44Issue(4)：233-255,23.DOI:10.19509/j.cnki.dzkq.tb20240481
雪峰隆起带金矿床有机地球化学特征及其成矿指示意义:以沃溪和万古金矿为例
Organic geochemical characteristics and their metallogenic indication of gold deposits in Xuefeng uplift zone:A case study of Woxi and Wangu gold deposits
摘要
Abstract
[Objective]Previous deep mineral exploration by organic hydrocarbons revealed that the deep-source superimposed anomalies observed in the deep and marginal parts of the Woxi and Wangu gold deposits differ significantly from the syngenetic superimposed anomalies identified in peripheral mineralized bodies.To further investigate the different halo-forming mechanisms between Au mineralization and organic matter formation.[Methods]this study focused on large to medium sized gold deposits(Woxi and Wangu)in the Xuefeng uplift belt and their peripheral mineralized bodies(characterized by good gold mineralization in shallow but poor deep mineralization).The analytical methods include rock-pyrolysis analysis(Rock-Eval),chloroform asphalt"A"extraction and fractional component separation quantification,saturated hydrocarbon analyzed by gas chro-matography-mass spectrometry(GC-MS),fluid inclusion,and C-H-O-S stable isotope analysis.These comparative investigations were conducted on their ore forming geological characteristics,organic geochemical signatures,fluid inclusion and isotopic geochemical features.This approach aims to elucidate the Au-organic matter mineralization and halo-forming mechanisms.[Results]The results indicate that:(1)Large-to-medium gold deposits and peripheral mineralized bodies have different metallogenic geological characteristics.The former underwent regional metamorphic hydrothermal filling and metasomatism followed by a superimposed mineralization involving deep-source fluids,while the latter only experienced regional metamorphic hydrothermal filling and metasomatism.(2)Both systems contain adsorbed organic and,the source of organic matter is similar with their original depositional environments.However,The total organic carbon(TOC)content in large-to-medium gold deposits exceeds that of peripheral mineralized bodies by over 50%,along with oxygen and hydrocarbon indices being 10 and 3-8 times lower,respectively.This indicates higher abundance and maturity of organic matter in large-to-medium gold deposits.(3)C-H-O-S stable isotope results demonstrate that metallogenic materials in large-to-medium gold deposits originates from the mantle,while the ore-forming fluids is a"deep-source fluids"formed by multi-stage evolution and mixing of mantle-derived fluids.In contrast,the metallogenic materials of peripheral mineralized bodies derived solely from ore-bearing strata,and their ore-forming fluids originated from shallow crustal fluids("shallow-source fluids").These differences reflect distinct fluid dynamics and mixing mechanisms,leading to divergent geological significances in mineralization.(4)Two type deposits have different organic matter sources in ore-forming fluids.The large-to-medium gold deposits contain not only the"incremental"organic matter introduced by deep-source fluids but also the adsorbed organic matter,whereas peripheral mineralized bodies contain only adsorbed organic matter.This likely explains the significantly higher TOC in the former.(5)The different halo-forming mechanisms between Au and organic matter mineralization.In large-to-medium gold deposits,Au transported by mantle-derived fluids predominantly exists as organic complexes ore chelates(e.g.,Au(CH3)2+,[Au(CH2NH2COO)]2+)and migrates via both liquid and gaseous phases.In contrast,Au in peripheral mineralized bodies associates with organic matter through physical adsorption,lacking geochemical significance of organic complexation/chelation.This distinction manifests as stronger organic hydrocarbon anomalies and strong correlation between Au and organic hydrocarbon by different carriers(ore bodies,overlying strata,or soils)in large-to-medium gold deposit.In peripheral mineralized bodies,hydrocarbon anomalies are weaker,and Au-hydrocarbon are poorer.These conclusions align with early organic hydrocarbon-based deep prospecting observations:"deep-source fluid mineralization—metallogenic materials derived from deep sources-strong Au-organic hydrocarbon correlations—deep-source superimposed anomalies—high deep prospecting potential"versus"shallow-source fluid mineralization—mineralizing material confined to strata—weak Au-organic hydrocarbon correlations-syngenetic superimposed anomalies-limited deep prospecting potential".[Conclusion]This study provides novel insights and directions for evaluating deep prospecting potential in exploration geochemistry.关键词
有机质/成矿机理/矿化体/金矿床/雪峰隆起带/沃溪金矿/万古金矿Key words
organic matter/metallogenic mechanism/mineralized/gold deposit/Xuefeng uplift zone/Woxi gold deposit/Wangu gold deposit分类
天文与地球科学引用本文复制引用
陈海龙,权永彬,陈平波,欧阳志强,张威,彭欢,卜建财,陈勇..雪峰隆起带金矿床有机地球化学特征及其成矿指示意义:以沃溪和万古金矿为例[J].地质科技通报,2025,44(4):233-255,23.基金项目
湖南省自然资源厅科技计划项目(2023-0145DZ) （2023-0145DZ）
