Fault-Related Carbonates as Quaternary Seismotectonic and Paleoclimate Archives (Monte Marine Fault, Central Apennines)

Abstract

Seismogenic faults shape continental landscapes, drive crustal deformation and influence fluid exchange between the lithosphere and atmosphere. Yet, quantitative links between fault activity, exhumation and near-surface environmental evolution remain poorly understood. Here, structural (meso- and micro-scale) investigations are integrated with carbonate geochemistry and geochronology to reconstruct the long-term spatio-temporal evolution of seismogenic faulting along the Monte Marine normal fault (MMNF) in the central Apennines, Italy. Field investigations and sampling of exhumed fault zones were complemented by analyses of faults exposed in paleoseismological trenches, together preserving carbonate mineralizations and cataclasites formed at different crustal depths and during successive stages of fault evolution. Carbon and oxygen stable isotope analyses (δ¹³C, δ¹⁸O), clumped isotope thermometry (Δ₄₇) and carbonate geochronology (U-Th, ¹⁴C dating) distinguish three structural and geochemical groups, spanning deeply exhumed fault zones, shallow fault-related carbonates, and near-surface carbonate concretions. Meteoric-derived footwall mineralizations along the MMNF record structurally controlled fluid flow from at least ∼481 ka, up to the Holocene surface-rupture record preserved in paleoseismological trenches (ca. 5.3–4.0 ka cal BC), pointing to long-lived, spatially distributed seismogenic activity. These data also constrain a maximum average exhumation rate of ∼1.57 ± 0.30 mm/yr across the fault system since ∼0.5 Ma. By linking fault-zone carbonate archives from exhumed structures with those exposed in paleoseismological trenches, this study provides a quantitative framework for reconstructing long-term fluid circulation, seismogenic fault activity and paleoclimatic conditions, tracing the evolution of fault–fluid systems across structural levels, from deeply exhumed fault zones to active surface ruptures in extensional mountain belts.