RT journal article
T1 Evidence of Hydrocarbon-Rich Fluid Interaction with Clays: Clay Mineralogy and Boron Isotope Data from Gulf of Cádiz Mud Volcano Sediments
A1 Martos-Villa, Rubén
A1 Mata, M. Pilar
A1 Williams, Lynda B.
A1 Nieto, Fernando
A1 Arroyo Rey, Xabier
A1 Sainz-Díaz, C. Ignacio
A2 Ciencias de la Tierra
K1 mud volcano
K1 B isotopes
K1 illite–smectite
K1 molecular modelling fluids
K1 Gulf of Cádiz
K1 hydrocarbons
AB Clay dehydration at great depth generates fluids and overpressures in organic-richsediments that can release isotopically light boron from mature organic matter, producing 10B-richfluids. The B can be incorporated into the tetrahedral sites of authigenic illite during the illitizationof smectite. Therefore, the crystal-chemical and geochemical characterization of illite, smectite orinterlayered illite–smectite clay minerals can be an indicator of depth (temperature) and reactionswith the basin fluids. The aim of this study was to determine the detailed clay mineralogy, B-contentand isotopic composition in illite–smectite rich samples of mud volcanoes from the Gulf of Cádiz,in order to evaluate interactions of hydrocarbon-rich fluids with clays. Molecular modeling of theillite structure was performed, using electron density functional theory (DFT) methods to examinethe phenomenon of B incorporation into illite at the atomic level. We found that it is energeticallypreferable for B to reside in the tetrahedral sites replacing Si atoms than in the interlayer of expandableclays. The B abundances in this study are high and consistent with previous results of B data oninterstitial fluids, suggesting that hydrocarbon-related fluids approaching temperatures of methanegeneration (150  C) are the likely source of B-rich illite in the studied samples.
PB MDPI
SN 2075-163X
YR 2020
FD 2020-08
LK http://hdl.handle.net/10498/23829
UL http://hdl.handle.net/10498/23829
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 14-nov-2026