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Basin-Scale Controls on Fault Zone Diagenesis: Observations from the Rio Grande Rift, NM

Randolph Williams
Geoscience, University of Wisconsin-Madison, Madison, WI, USA
[email protected]

Abstract

Approaches to evaluating fault seal typically consider only variations in host-rock lithology and throw, neglecting the effects of fault-zone diagenesis. This is in part due to difficulties in constraining the fluid sources and pathways responsible for fault zone cementation at the basin scale. As cement volume is directly related to fluid flux, chemistry, and temperature, prediction of the basin-scale distribution of fault zone cementation requires better knowledge of the development of the regional flow pathways which ultimately control the distribution of fault-zone cements throughout basin evolution. I propose to examine the record of flow pathways responsible for fault zone cementation in the well characterized Rio Grande rift of New Mexico to better understand controls on the distribution of carbonate cements in rift basins in general. 'Clumped-isotope' paleothermometry and standard stable isotope analysis will be used to constrain the origin(s) and temperature(s) of fluids responsible for fault zone cementation in the Rio Grande rift. Additionally, 87Sr/86Sr analysis, elemental analysis, and U-series geochronology will be used to further constrain the fluid source and timing of fault zone cementation. By relating our findings to structural setting and displacement it should be possible to predict which faults in a given rift basin are most likely to serve as large-scale flow conduits at different stages of basin evolution, and how cementation has contributed to sealing in these faults over time.

AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects