The origin of celestine–quartz–calcite geodes associated with a basaltic dyke, Makhtesh Ramon, Israel

Anenburg, Michael and Bialik, Or M. and Vapnik, Yevgeny and Chapman, Hazel J. and Antler, Gilad and Katzir, Yaron and Bickle, Mike J. (2014) The origin of celestine–quartz–calcite geodes associated with a basaltic dyke, Makhtesh Ramon, Israel. Geological Magazine, 151 (05). pp. 798-815. ISSN 0016-7568, ESSN: 1469-5081 DOI 10.1017/S0016756813000800

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Official URL: http://dx.doi.org/10.1017/S0016756813000800

Abstract

Spectacular celestine geodes occur in a Jurassic peri-evaporitic sequence (Ardon Formation) exposed in Makhtesh Ramon, southern Israel. The geodes are found only in one specific location: adjacent to an intrusive contact with a Lower Cretaceous basaltic dyke. Celestine, well known in sedimentary associations worldwide and considered as a low temperature mineral, may therefore be associated with magmatic-induced hydrothermal activity. Abundant fluid inclusions in celestine provide valuable information on its origin: gas-rich inclusions in celestine interiors homogenized at T>=200°C whereas smaller liquid-rich inclusions record the growth of celestine rims at T<=200°C. Near 0°C melting temperatures of some fluid inclusions and the occurrence of hydrous Ca-sulphate solid crystals in other inclusions indicate that celestine precipitated from variably concentrated Ca-sulphate aqueous solutions of meteoric origin. Celestine crystallized from meteoric water heated by the cooling basaltic dyke at shallow levels (c. 160 m) during a Lower Cretaceous thermal perturbation recorded by regional uplift and magmatism. The 87Sr/86Sr ratio of geode celestine, 0.7074, is similar to that measured in the dolostones of the host Jurassic sequence, but differs markedly from the non-radiogenic ratio of the dyke. Strontium in celestine was derived from dolostones preserving the 87Sr/86Sr of Lower Jurassic seawater, while sulphur (δ34S = 19.9‰) was provided by in situ dissolution of precursor marine gypsum (δ34S = 16.8‰) indicated by relict anhydrite inclusions in celestine. Low-temperature meteoric fluid flow during the Campanian caused alteration of the dyke into secondary clays and alteration of geodal celestine into quartz, calcite and iron oxides.

Item Type: Article
Uncontrolled Keywords: 2014AREP; IA68;
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Geological Magazine
Volume: 151
Page Range: pp. 798-815
Identification Number: 10.1017/S0016756813000800
Depositing User: Sarah Humbert
Date Deposited: 25 Aug 2014 22:09
Last Modified: 07 Sep 2014 01:41
URI: http://eprints.esc.cam.ac.uk/id/eprint/3094

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