Sedimentology and Mineralogy of Dolomitic Coorong Lakes, South Australia

摘要: ABSTRACT Coorong dolomites are true "primary dolomites"; that is, dolomite is precipitating where there was nothing before and not replacing an earlier carbonate mineral. Dolomites in the various lakes of coastal plain South Australia occur three mineralogical associations; Dolomite ± Mg-calcite (widespread) Magnesite (common northwest) aragonite hydromagnesite (rare only northwest). Most Holocene occurrences near region associated with Mg-calcite. Only more arid settings found at northwestern end region, Salt Creek, commonly association magnesite occasionally aragonite. surface sediments Creek such as Pellet Lake Milne often lake center about margin. The tend to be magnesian-rich than Mg-calcite, a direct reflection chemistry mother waters. Waters which precipitate typically concentrated magnesium-rich waters pre ipitating hence co-precipitated will also magnesium-rich. Textures vertical sequences from largely independent mineralogy; similar transitions whether filling carbonate, magnesian carbonates, or gypsum. has been main mineral concern previous geological studies this area, yet it makes up no 10% minerals forming surficial deposits across plain. hydrological model should used explain widespread dolomitization ancient supratidal shelf carbonates. counterparts rock record facies mosaic lacustrine sitting much extensive paleoaquifer.