ObjectivePrevious 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. Methodsthis 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 chromatography-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. ResultsThe 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". ConclusionThis study provides novel insights and directions for evaluating deep prospecting potential in exploration geochemistry.