Syndepositional Deformation Features In High-Relief Carbonate Platforms: Long-Lived Conduits for Diagenetic Fluids

• DOI: 10.2110/jsr.2013.3
• Publication Date: 2013-01-29T20:56:53Z
• Authors: D. A. Budd; E. L. Frost; K. W. Huntington; P. F. Allwardt
• Keywords: Electrical conduit

Abstract Syndepositional faults and fractures are known to affect early fluid flow in carbonate platforms. Less clear is whether they active conduits throughout the entire history of platform strata. Syndeformational Permian (late Guadalupian) carbonates exposed Dark Canyon, Guadalupe Mountains, New Mexico, U.S.A., address this question. Transmitted-light cathodoluminescent petrography, stable-isotope fluid-inclusion analyses, clumped-isotope thermometry show that there were multiple episodes fracturing, dissolution, cementation, replacement fractures. Dolomite cement or dolomitized marine cements line walls some indicate syndepositional reflux evaporated seawaters through Fine- medium-crystalline, luminescently zoned calcite may overlie dolomite cements, fracture where those phases absent, karst breccia on walls. The δ18O values (−8.8 −14.0‰ VPDB) temperatures (16° 32°C) precipitation from meteoric fluids (δ18OSMOW −6.2 −10.5‰) associated with episodic sea-level lowstands during development high-frequency depositional sequences. calcites can themselves be fractured, rotated, recemented, indicating recurrent deformation influx. Evaporite once dominant pore-filling phase fractures, forming both before after cements. earliest evaporites formed deposition Tansill limestone, probably same brines dolomites. Evaporites postdate did not form until Permo-Triassic burial, when geomechanical analysis indicates likely reactivated could have been sourced overlying bedded evaporite. All evaporite subsequently calcitized, mainly by coarse-crystalline, inclusion-rich warm (59° 96°C) fluids. Calculated isotopic compositions −0.5 −4.7‰) imply mixing oil-field brines. Carbon isotope (+2 −17‰) microbial degradation hydrocarbons fluids, but all. Geomechanical potential for failed (reactivated) Basin Range extension, basinal interpreted migrated upward event. Platform-margin (unassociated faults) witnessed cooler 65°C) than outer-shelf (70° because tapped waters greater depths. most recent generated dissolution features laminated speleogenetic calcites, which result intrastratal karsting exhumation weathering. Diagenetic equivalent observed adjacent limestones, suggesting communication between matrix diagenetic rocks. complex paragenesis also only fluid-flow networks, impact a rock's if changing stress fields.