Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas)

Abstract

Research Article| July 31, 2018 Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas) Hannah L. Hubert; Hannah L. Hubert Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Eugene C. Rankey; Eugene C. Rankey Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Christopher Omelon Christopher Omelon Kansas Interdisciplinary Carbonates Consortium, Department of Geology, University of Kansas, Lawrence, Kansas 66045, U.S.A. Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2018) 88 (7): 827–849. https://doi.org/10.2110/jsr.2018.42 Article history first online: 31 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Hannah L. Hubert, Eugene C. Rankey, Christopher Omelon; Organic Matter, Textures, and Pore Attributes of Hypersaline Lacustrine Microbial Deposits (Holocene, Bahamas). Journal of Sedimentary Research 2018;; 88 (7): 827–849. doi: https://doi.org/10.2110/jsr.2018.42 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract Discovery of lacustrine microbialite reservoirs in South Atlantic pre-salt has motivated the search for analogs for perspectives on their deposition and initial porosity. Although previous efforts mapped spatial patterns and produced facies models of large microbial lacustrine systems, details of the origins of microbialite fabrics are less well constrained. To address these unknowns, this study evaluates the influence of organic-matter source, abundance, and growth habit on Holocene microbialite fabrics. Integrated multi-scale analyses characterize fabrics of Holocene microbialites in a small (< 1 km2), shallow (< 1 m), hypersaline, alkaline lake on Crooked–Acklins Platform in the southern Bahamas. The results of analyses indicate systematic distribution of surface sediment across the lake, from various types of unlithified microbial mats to calcareous microbialites; bottom type relates to water depth. Spherules with laminae of radial aragonite are common in organic-rich mats, and can have competitive growth boundaries. Calcareous microbialites in the lake center can reach up to 60 cm tall and 2+ m across, and include macrofabrics and microfabrics that vary considerably, across micrometer to meter scales. Porosity varies from 43 to 59%, in pore types ranging from intra-fibrous (IF), breccia (BR), vuggy (VUG), intra- (WL) and inter-laminar (IL), digitate (DG), to branching (BRA). Microfabrics are not unique to individual macrofabrics, and organic-matter source is similar among fabrics. The abundance of organic matter and growth habit of organics on the outer parts of microbialites varies markedly among fabrics, suggesting that these parameters may control rock fabric. The occurrence of Mg silicates in association with these microbialites may favor preservation of the depositional pores. Although ultimate preservation is unknown, understanding the genesis of primary fabrics may provide insights into possible pore evolution in reservoir analogs. You do not currently have access to this article.