Regional and down-core distributions of authigenic carbonates, ferric smectite, vivianite, gypsum, barite, AVS, pyrite and other iron-sulfide minerals in sediments off SW Taiwan were determined by electron and optical microscopy. In the studied region, zonal patterns and transitions of authigenic materials in particular iron sulfides with depth are characteristic of non-steady state early diagenesis and can be correlated to the sulfate-methane transition zone (SMTZ) under the influence of intermittent and site-specific operations of intense anaerobic oxidation of methane (AOM) at topographic heights and their adjoining areas. Such a phenomenon is most pervasive in the Tainan Ridge, Yungan Ridge, and Good Weather Ridge sediments that may have been repeatedly conditioned by fluctuated methane seepage. Advanced growth or overgrowth of pyrite can be largely attributed to prominent AOM associated with high methane flux and were utilized in conjunction with SMTZ depth to highlight characteristic patterns of AOM properties in different tectonic units. By and large, the Tainan Ridge, Yungan Ridge, and Good Weather Ridge sediments in the fold-and-thrust belt is dominated by present-day active and strong AOM reactions while the Fangliao Ridge-Kaoping Canyon area in the upper slope domain with extensive mud diapirism and volcanism and the Formosa and Jiulong ridges as part of the passive South China Sea continental slope are accentuated by ancient records of advanced AOM as marked by mineral authigenesis with limited current activities of AOM. The regional contrasting patterns of AOM properties defined by mineral authigenesis and SMTZ depth highlight geological controls due to tectonic diversities among the gas-hydrate potential areas off SW Taiwan.
|Translated title of the contribution||Authigenic minerals in gas-hydrate potential areas offshore SW Taiwan: An overview|
|Number of pages||36|
|Journal||Special Publication of the Central Geological Survey|
|Publication status||Published - 2016 Dec|
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)