About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

AAPG Bulletin, V. 98, No. 9 (September 2014), P. 17891809.

Copyright copy2014. The American Association of Petroleum Geologists. All rights reserved.

DOI: 10.1306/05121413127

Dimensions, texture-distribution, and geochemical heterogeneities of fracture–related dolomite geobodies hosted in Ediacaran limestones, northern Oman

Veerle Vandeginste,1 Cédric M. John,2 John W. Cosgrove,3 and Christina Manning4

1 Imperial College London, Department of Earth Science and Engineering and Qatar Carbonate and Carbon Storage Research Centre, London SW7 2BP, United Kingdom; [email protected]
2 Imperial College London, Department of Earth Science and Engineering and Qatar Carbonate and Carbon Storage Research Centre, London SW7 2BP, United Kingdom; [email protected]
3 Imperial College London, Department of Earth Science and Engineering and Qatar Carbonate and Carbon Storage Research Centre, London SW7 2BP, United Kingdom; [email protected]
4 Royal Holloway University of London, Department of Earth Sciences, Egham Hill, Egham, Surrey TW20 0EX, United Kingdom; [email protected]

ABSTRACT

Predicting spatial distribution, dimension, and geometry of diagenetic geobodies, as well as heterogeneities within these bodies, is challenging in subsurface applications, and can impact the results of reservoir modeling. In this outcrop–based study, we generated a data set of the dimensions of fracture–related dolomite geobodies hosted in Ediacaran (Khufai Formation) limestones of the Oman Mountains that are up to several hundreds of meters long and a few tens of meters wide. The dolomite formed under burial conditions by fluids that interacted with siliciclastic layers, as demonstrated by the enriched Fe (up to 4.4%) and Mn (up to 0.8%) contents and BLTN13127eq1 (BLTN13127eq2) signatures. Dolomitization probably occurred during the Hercynian Orogeny (or pre-Permian) because dolomitization predates some folding and pre-Permian rocks have seen intense deformation related to the Carboniferous Hercynian Orogeny. Moreover, dolomitization occurred between the onset and termination of bedding-parallel stylolitization and thus most likely before deep burial related to the Alpine Orogeny. Hence, dolomitization most likely occurred before deep burial related to the Alpine Orogeny and during or following the intense deformation related to the Carboniferous Hercynian Orogeny had affected pre–Permian rocks. The clumped–isotope signature yields a temperature of approximately 260°C (500°F), interpreted as the apparent equilibrium temperature obtained during uplift after deepest burial during the Late Cretaceous. Lateral transects across the dolomite bodies show that zebra dolomite textures are common throughout the body and that vugs are more common at the rim than the center of the bodies. Moreover, a weak geochemical trend exists with more depleted BLTN13127eq3, Fe, and Mn concentrations in the core than at the rim of the dolomite bodies. These results show that minor heterogeneities exist within the dolomite bodies investigated. These data contrast with previous studies, in which more significant variation is reported in width of the dolomitization halo and texture for larger dolomite bodies that formed in host rocks more permeable than the examples from the Oman Mountains.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].