Hydrothermal dolomitization of Jurassic-Cretaceous limestones in the southern Alps (Italy): Relation to tectonics and volcanism

Abstract

Research Article| May 01, 1990 Hydrothermal dolomitization of Jurassic-Cretaceous limestones in the southern Alps (Italy): Relation to tectonics and volcanism Cinzia Cervato Cinzia Cervato 1Institute of Geology, Swiss Federal Institute of Technology, Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Author and Article Information Cinzia Cervato 1Institute of Geology, Swiss Federal Institute of Technology, Zürich, Switzerland Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (5): 458–461. https://doi.org/10.1130/0091-7613(1990)018<0458:HDOJCL>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Cinzia Cervato; Hydrothermal dolomitization of Jurassic-Cretaceous limestones in the southern Alps (Italy): Relation to tectonics and volcanism. Geology 1990;; 18 (5): 458–461. doi: https://doi.org/10.1130/0091-7613(1990)018<0458:HDOJCL>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Dolomitization has affected up to 750 m of the Jurassic and Cretaceous pelagic carbonate sequence of the southern continental margin of the Alpine Tethys; the sequence crops out in the southern Alps of Italy (Monti Lessini). Late Paleocene to Miocene extrusion of basaltic tuffs, breccias, and lavas was contemporaneous with the dolomitization and was associated with extensive tectonism in an ancient back-arc basin. More than 200 samples were analyzed by X-ray diffraction, cathodoluminescence, scanning electron microscopy, stable isotope ratios (carbon, oxygen, strontium), and clay mineralogy. The dolomite contains 40% to 50% MgCO3. In thin section, the crystal size distribution is unimodal (about 100 μm), possibly indicating a single nucleation for the main crystallization phase. The δ13C of the dolomite is not appreciably different from the undolomitized pelagic limestone (+1.0‰ to +2.0‰ Peedee belemnite [PDB]). The δ18O variation (-5.0‰ to-13.0‰ PDB) is due to temperature variation in the system. The 87Sr/86Sr ratio in the dolomite (0.70839-0.70867) is consistent with the ratio in late Oligocene-Miocene marine water. Clay minerals in limestone and dolomite differ in the presence of neoformed Mg-chlorite, indicating a maximum temperature of about 150 °C for dolomitization.The dolomite is suggested to have a hydrothermal origin. The heat flow associated with volcanism allowed marine water to penetrate the system and circulate in convective cells through the tectonic breccias, locally dolomitizing the limestone. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.