Episodic exhumation of the Appalachian orogen in the Catskill Mountains (New York State, USA)

et al., 2004; McKeon et al., 2014) and there is contradictory information from thermal models. First-generation modeling programs commonly produced a late-stage cooling artifact (e.g., Ketcham et al., 1999; Roden-Tice et al., 2009), and without supporting geologic evidence, a confident interpretation of late-stage rapid cooling from such models was problematic. We apply multi-kinetic inverse thermal modeling that utilizes apatite grains? variable resistance to annealing (via measuring the diameter of fission-track etch pits, Dpar as a composition proxy), which does not produce spurious latestage cooling artifacts. Low-temperature thermochronologic results from samples collected over a -1 km vertical Increasing evidence indicates the eastern North American passive margin has not remained tectonically quiescent since Jurassic continental breakup. The identification, timing, resolution, and significance of post-orogenic exhumation, notably an enigmatic Miocene event, are debated. We add insight by constraining the episodic cooling and exhumation history of the Catskill Mountains (New York, USA) utilizing apatite fission-track thermochronology and apatite (U-Th)/He data from a -1 km vertical profile. Multi-kinetic inverse thermal modeling constrains three phases of cooling: Early Jurassic to Early Cretaceous (1?3 ?C/m.y.), Early Cretaceous to early Miocene (-0.5 ?C/m.y.), and since Miocene times (1?2 ?C/m.y.). Previous thermochronologic studies were unable to verify late-stage cooling and/or exhumation (typically post-Miocene and younger) because late-stage cooling was commonly a spurious artifact of earlier mono-kinetic annealing algorithms. Episodic cooling phases are correlative with rifting, passive-margin development, and drainage reorganization causing landscape rejuvenation. Geomorphologic documentation of increased offshore mid-Atlantic sedimentation rates and onshore erosion support the documented accelerated Miocene cooling and exhumation.

Automated summary

This study utilizes multi-kinetic inverse thermal modeling to constrain the cooling and exhumation history of the Catskill Mountains (New York, USA) through apatite fission-track thermochronology and apatite (U-Th)/He data. By examining three cooling phases - from Early Jurassic to Early Cretaceous (1-3 °C/m.y.), Early Cretaceous to early Miocene (-0.5 °C/m.y.), and since Miocene times (1-2 °C/m.y.), correlations between episodic cooling phases and geologic processes such as tectonic uplift are revealed.