Hydrogen and Ar-40/Ar-39 isotope evidence for multiple and protracted paleofluid flow events within the long-lived North Anatolian Keirogen (Turkey)

Boles, Austin, van der Pluijm, Ben, Mulch, Andreas, Mutlu, Halim, Uysal, I. Tonguc and Warr, Laurence N. (2015) Hydrogen and Ar-40/Ar-39 isotope evidence for multiple and protracted paleofluid flow events within the long-lived North Anatolian Keirogen (Turkey). Geochemistry Geophysics Geosystems, 16 6: 1975-1987. doi:10.1002/2015GC005810


Author Boles, Austin
van der Pluijm, Ben
Mulch, Andreas
Mutlu, Halim
Uysal, I. Tonguc
Warr, Laurence N.
Title Hydrogen and Ar-40/Ar-39 isotope evidence for multiple and protracted paleofluid flow events within the long-lived North Anatolian Keirogen (Turkey)
Formatted title
Hydrogen and 40AR/39Ar isotope evidence for multiple and protracted paleofluid flow events within the long-lived North Anatolian Keirogen (Turkey)
Journal name Geochemistry Geophysics Geosystems   Check publisher's open access policy
ISSN 1525-2027
Publication date 2015-06-28
Sub-type Article (original research)
DOI 10.1002/2015GC005810
Open Access Status Not yet assessed
Volume 16
Issue 6
Start page 1975
End page 1987
Total pages 13
Collection year 2016
Language eng
Formatted abstract
We present a new approach to identifying the source and age of paleofluids associated with low-temperature deformation in the brittle crust, using hydrogen isotopic compositions (δD) and 40Ar/39Ar geochronology of authigenic illite in clay gouge-bearing fault zones. The procedure involves grain-size separation, polytype modeling, and isotopic analysis, creating a mixing line that is used to extrapolate to δD and age of pure authigenic and detrital material. We use this method on samples collected along the surface trace of today's North Anatolian Fault (NAF). δD values of the authigenic illite population, obtained by extrapolation, are −89 ± 3‰, −90 ± 2‰, and −97 ± 2‰ (VSMOW) for samples KSL, RES4-1, and G1G2, respectively. These correspond to δD fluid values of −62‰ to −85‰ for the temperature range of 125°C ± 25°, indistinguishable from present-day precipitation values. δD values of the detrital illite population are −45 ± 13‰, −60 ± 6‰, and −64 ± 6‰ for samples KSL, G1G2, and RES4-1, respectively. Corresponding δD fluid values at 300°C are −26‰ to −45‰ and match values from adjacent metamorphic terranes. Corresponding clay gouge ages are 41.4 ± 3.4 Ma (authigenic) and 95.8 ± 7.7 Ma (detrital) for sample G2 and 24.6 ± 1.6 Ma (authigenic) and 96.5 ± 3.8 Ma (detrital) for sample RES4-1, demonstrating a long history of meteoric fluid infiltration in the area. We conclude that today's NAF incorporated preexisting, weak clay-rich rocks that represent earlier mineralizing fluid events. The samples preserve at least three fluid flow pulses since the Eocene and indicate that meteoric fluid has been circulating in the upper crust in the North Anatolian Keirogen since that time.
Keyword Illite
Hydrogen isotopes
Ar-40
Ar-39 geochronology
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2016 Collection
 
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