Dolomite cation order in the geological record

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Pina Martínez, Carlos Manuel and Pimentel Guerra, Carlos and Crespo López, Ángel (2020) Dolomite cation order in the geological record. Chemical geology, 547 (119667). ISSN 0009-2541

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Abstract

Dolomite is a carbonate mineral frequently found in sedimentary rocks from Proterozoic to Holocene. In the Iberian Peninsula, dolomites appear in a wide number of geological formations and they can be considered as representative of dolomites crystallised in most (post)sedimentary environments on Earth. In this paper, we present a first systematic study of the cation order of dolomites formed from Neoproterozoic to late Holocene. We found that the lowest values of cation order (quantified by measuring I01.5/I11.0 intensity ratios on diffractograms) mainly correspond to dolomites formed in about the last 30 Myr. In contrast, older dolomites usually reach maximum I01.5/I11.0 intensity ratios. Furthermore, higher values of cation order seem to be related to higher values of the full width half maximum of 10.4 diffraction peaks (FWHM10.4). Assuming that a decrease in FWHM10.4 (i.e. an increase in the crystallite size) in sedimentary environments indicates mineral ripening, our results show that Mg-Ca ordering in dolomites might take place mainly by a dissolution-(re)crystallisation ageing process operating over large geological periods.


Item Type:Article
Uncontrolled Keywords:Dolomite; Iberian Peninsula; Geological record; Cation ordering; Crystallite size; Dissolution-crystallisation; X-ray Powder Diffraction
Subjects:Sciences > Geology > Crystallography
ID Code:60827
Deposited On:09 Jun 2020 10:03
Last Modified:09 Jun 2020 11:11

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