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Nano-crystal formation of TiO (sub 2) polymorphs brookite and anatase due to organic-inorganic rock-fluid interactions

Hans-Martin Schulz, Richard Wirth and Anja Schreiber
Nano-crystal formation of TiO (sub 2) polymorphs brookite and anatase due to organic-inorganic rock-fluid interactions
Journal of Sedimentary Research (February 2016) 86 (2): 59-72

Abstract

The occurrence of the titania polymorphs brookite and anatase as nano-crystals in organic matter-rich sediments of differing age and thermal maturity has been investigated by means of a multidisciplinary analytical approach (FIB-TEM, organic geochemistry, and petrography). It was the aim of the study to analyze the formation mechanisms, fate and behavior of the titania nano-crystals as a result of organic-inorganic rock-fluid interactions. Brookite nano-crystals have been detected in immature Mediterranean sapropels of Quaternary age, but anatase also occurs in deeper and older black shales (Furongian Alum Shale, Sweden; Devonian to Carboniferous Bakken Shale, Williston Basin, USA). Whereas anatase prevails as single crystals, brookite nano-crystals often are agglomerated. Single brookite nano-crystals from Posidonia Shale (Lower Jurassic, Northern Germany) have increasing crystal diameters with increasing thermal maturity. Exclusively anatase nano-crystals both as single crystals or as agglomerates have been detected at oil-water contacts in oilfields, and along fractures with fluid flow enriched in dissolved organic carbon. Titania nano-crystal precipitation, growth (and agglomeration) takes place in the pore water of micro-environments at low to high temperatures and where low pH is coupled to the occurrence of dissolved organic components. Low sedimentation rates preserving a critical geochemical environment or higher temperatures seem major controls for the precipitation of anatase and its tendency not to agglomerate.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 86
Serial Issue: 2
Title: Nano-crystal formation of TiO (sub 2) polymorphs brookite and anatase due to organic-inorganic rock-fluid interactions
Affiliation: GeoForschungsZentrum Potsdam, Potsdam, Germany
Pages: 59-72
Published: 201602
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 58
Accession Number: 2016-083545
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N47°15'00" - N55°00'00", E05°49'60" - E15°00'00"
N55°15'00" - N69°15'00", E11°00'00" - E24°15'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201640
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