Timescales of faulting through calcite geochronology: A review

How the geochemistry of syn-kinematic calcite cement depicts past fluid flow and assists structural interpretations: a review of concepts and applications in orogenic forelands

“…In cases where fluid mixing is not supported by data, authors have considered that the opening of the fracture triggers the precipitation by locally reducing pCO 2 (Beaudoin et al 2014a;Cruset et al 2018). It is interesting to note that the recent study of Roberts and Holdsworth (2022) suggests that veins developed as crack seal are optimal to access the past fluid at the time of deformation, even though this needs to be considered with care as Bons et al (2012) clearly showed that a crack seal can be related to multiple events of deformation.…”

“…Classically, the concentration in 230 Th, 232 Th, 234 U and 238 U for the U-series geochronology and in 235 U, 238 U, 207 Pb, 206 Pb and 204 Pb for U-Pb geochronology is obtained by isotope dilution followed by thermal ionization mass spectrometry (TIMS) or inductively coupled plasmamass spectrometry (ICP-MS), a technique that has a high precision and accuracy but is time-consuming and expensive (Brannon et al 1996;Rasbury & Cole, 2009), even though recent development makes it faster (Engel et al 2020). The recent reduction of the concentration threshold for the detection of trace elements using laser ablation coupled to ICP-MS (LA-ICP-MS) has enabled a democratization of LA-ICP-MS geochronology, that paved the way to obtaining the U-Pb absolute age of syn-kinematic calcite cements in veins (see Roberts et al, 2020, for a review) and faults (see Roberts & Holdsworth, 2022, for a review), with further developments of U-Pb dating of dolomite phases (Bar et al 2021;Motte et al 2021;Su et al 2022). In contrast, the very low 230 Th concentration in carbonates severely hampers the applicability of LA-ICP-MS to U-series geochronology (e.g.…”

“…Another important point is that the ages obtained from vein cements might not be straightforwardly interpreted as representative of the entire duration of the deformation event that developed the veins, so a certain number of data might be required to cover the entire timespan during which a deformation phase affected the rock . In faults, the age of a cement can be younger than the fault activity because of a subsequent fluid flow (Roberts et al 2021;Roberts & Holdsworth, 2022). To check whether the U-Pb age legitimately represents the age of precipitation, a recent approach couples the Δ 47 CO 2 palaeothermometry to U-Pb geochronology to check whether the vein cement precipitated at thermal equilibrium with the host or not (Pagel et al 2018;Hoareau et al 2021a;Muñoz-López et al 2022).…”

Episodic Reactivation of Carbonate Fault Zones with Implications for Permeability – an Example from Provence, Southeast France

“…Crack-seal textures and slickenfibers are the most reliable structures indicative of syn-tectonic fracturing and/or faulting (e.g. Ukar and Laubach, 2016;Roberts and Holdsworth, 2022). By contrast, blocky calcite cement is less reliable since deposition of calcite may have occurred late with respect to deformation (post-kinematic).…”

Far-field brittle deformation record in the eastern Paris Basin (France)

“…Since no syntaxial or antitaxial growth orientations were identified (sensu Bons et al 2012), the syn-kinematic precipitation of calcite crystals within tension gashes is unclear (Roberts & Holdsworth, 2022). Field observations have revealed that tension gashes are generally associated with tectonic stylolites, suggesting syn-kinematic calcite dissolution and recrystallization (André et al 2010).…”