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Past hot fluid flows in limestones detected by Delta (sub 47) -(U-Pb) and not recorded by other geothermometers

Benjamin Brigaud, Magali Bonifacie, Maurice Pagel, Thomas Blaise, Damien Calmels, Frederic Haurine and Philippe Landrein
Past hot fluid flows in limestones detected by Delta (sub 47) -(U-Pb) and not recorded by other geothermometers
Geology (Boulder) (May 2020) Pre-Issue Publication


Geothermometers are commonly used to reconstruct the diagenetic and thermal history of rocks. However, characterizing the timing, origin, and temperature of paleofluid flow remains challenging because it must be assessed indirectly through the analysis of microscopic cements that precipitate and fill intergranular spaces during fluid circulation. Here, we measure both the clumped isotope (Delta (sub 47) ) temperature and in situ U-Pb age of individual diagenetic calcite cements within a sedimentary section of the Paris Basin (France), whose thermal history has been previously inferred to be <60 degrees C. We show that cementation occurred during two stages associated with major events at the western European lithospheric scale: (1) the Bay of Biscay rifting (Late Jurassic-Early Cretaceous), and (2) north-south Pyrenean compression (Eocene) followed by east-west extension during the European Cenozoic rift system event (Oligocene). Related to both events, we report unexpectedly hot fluids, up to 110 degrees C, contrasting with the lower temperatures inferred from other geothermometers (e.g., fluid inclusions, clay minerals, apatite fission tracks, maturity of organic matter by Rock-Eval pyrolysis, or vitrinite reflectance). These high temperatures (>70 degrees C) have been measured for calcite cements containing single-phase aqueous fluid inclusions, challenging the commonly accepted assertion that the absence of nucleation of a vapor phase indicates crystallization at low temperature ( approximately <70 degrees C). We suggest that the kinetics of mineralization events prevented the recording of short-lived hot fluid flows by other geothermometers.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: Pre-Issue Publication
Title: Past hot fluid flows in limestones detected by Delta (sub 47) -(U-Pb) and not recorded by other geothermometers
Affiliation: Universite Paris-Saclay, Geosciences Paris Sud, Orsay, France
Published: 20200519
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2020-049504
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 1 table, geol. sketch map
N48°00'00" - N50°00'00", E01°00'00" - E05°00'00"
Secondary Affiliation: Institut de Physique du Globe de Paris, FRA, FranceAndra, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202014
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