Tracing paleofluid sources using clumped isotope thermometry of diagenetic cements along the Moab Fault, Utah

Abstract

Interactions among fluids, deformation structures, and chemical changes in sediments impact deformation of the shallow crust, influencing the preservation and extraction of the economic resources it contains. These interactions have been studied along the Moab Fault, in the Paradox Basin, Utah, where diagenetic cements, joints, cataclastic deformation bands and slip surfaces developed during faulting are thought to control fault permeability. Previous fluid inclusion micro-thermometry and stable isotopic data from calcite cements collected along segments of the Moab Fault suggest cements precipitated from hot basin fluids that migrated up the fault and interacted with a shallower meteoric groundwater source. In this study, we investigate the interactions of these fluids with deformation structures using clumped isotope thermometry of calcite cements along the Moab Fault. Guided by prior high-resolution mapping of deformation structures and calcite cements, we measured the growth temperature of calcite cements collected at varying distance from fault segments and fault intersections. Cement temperatures from individual segments vary greatly; cements along a relatively simple fault segment indicate temperatures ranging from 67 to 128°C, similar to previously published fluid inclusion homogenization temperatures from a cement sample collected in the same locality, while a nearby fault intersection hosts cements with temperatures of 13 to 88°C. The spatial pattern of cement temperatures revealed by clumped isotope thermometry suggests that intensely jointed zones associated with fault intersections enable rapid down-fault migration of cool surface waters and that deformation-band faults with their associated slip surfaces may further compartmentalize fluid flow, restricting fluid sources to warm waters thermally equilibrated with the country rock outside the jointed zone. Our data confirm that the relationship between faults and fluid flow can vary greatly over short length scales, and suggest that some fracture zones can be highly conductive to depths as great as 2 km.

Clumped isotope thermometry in deeply buried sedimentary carbonates: The effects of bond reordering and recrystallization

“…Thus, it is important to explore emergent techniques, such as carbonate clumped isotope thermometry (Eiler, 2007(Eiler, , 2011, which can be diversely applied to virtually any carbonate in a range of thermal settings. For example, the technique has been applied in the diagenetic tempera ture range (~125 °C and lower) to recon struct mineralization temperatures and to reveal fluid chemistries associated with cements and fractures (e.g., Huntington et al, 2011;Budd et al, 2013;Loyd et al, 2013), faults (Swanson et al, 2012;Bergman et al, 2013), and concre tions (Loyd et al, 2012;Dale et al, 2014). At higher temperatures, clumped isotopes may be useful for reconstructing cooling rates (e.g., Passey and Henkes, 2012) and refining burial histories (e.g., Henkes et al, 2014).…”

Analytical effects on clumped isotope thermometry: Comparison of a common sample set analyzed using multiple instruments, types of standards, and standardization windows

“…The measurement of the organization of multiple rare isotopes within a molecule opens up avenues of scientific inquiry that are not accessible with single isotope systems, such as the long‐standing problem of determining the respective influences of water isotopic values and carbonate growth temperatures on the oxygen isotope composition of carbonate minerals. The carbonate clumped isotope thermometer has been deployed in a growing number of applications, such as paleoclimatology, sedimentology and basin analysis, and tectonics because it is completely independent of the sample's bulk isotopic composition and allows temperatures to be measured directly without knowledge of the isotopic composition of water. In this application, the overexpression of 13 C‐ 18 O bonds within the carbonate lattice relative to a randomized mixture of isotopes (denoted Δ 47 ) is controlled by the formation temperature of the carbonate mineral, assuming that it formed at equilibrium …”

What do we really know about early diagenesis of non-marine carbonates?

“…Clumped isotope thermometry can help in constraining conditions of diagenesis in carbonates at temperatures higher or lower than temperature of formation (Swart, 2015) and to reconstruct burial depths and fluid flow history (Huntington et al, 2006;Eiler, 2011;Bergman et al, 2013;Ritter et al, 2017;Sample et al, 2017). According to Ferry et al (2011) clumped isotope thermometry should record the depositional temperature, diagenesis, and recrystallization of carbonate minerals up to at least 100-200°C, though caution is needed (Ritter et al, 2017).…”