Dr. Renas I. Koshnaw

Research interest

My scientific journey has been driven by the quest to unravel the dynamic interplay between Earth’s interior and exterior through diverse geological approaches. I do field-based research and integrate various methods in earth sciences, including siliciclastic stratigraphy, magnetostratigraphy, structural measurements, thermochronology, geochronology, and geochemistry, combined with geophysical data such as seismic reflection profiles and teleseismic tomography.

Why is the NW Zagros foreland basin deeper than what the nearby mountain loads alone would suggest?

This study uncovered a two-stage basin evolution driven by surface topography and deep earth processes. During the early Miocene, subsidence resulted from the combined effects of mountain topography and the sinking Neotethys plate. During the middle Miocene, a horizontal tear in the Neotethys plate triggered asthenospheric mantle flow, reshaping the basin's architecture and amplifying subsidence in its southeastern segment.

The Zagros collisional zone tectonic evolution

This research involved determining the maximum age of the Arabia–Eurasia collision, identifying the basin type of the suture zone sediments, and reconstructing the tectonic history since the Paleocene. The main utilized methods were detrital zircon U-Pb and (U-Th)/He double dating. Dating continental collision is important because it provides quantitative constraints on global physical processes, plate tectonic kinematics, and reconstruction of paleogeography and paleoclimates in response to mountain-building processes. These results were published in Solid Earth.

Timing of the Arabia-Eurasia continental collision

This research documented the detrital zircon provenance and timing of deposition of the oldest synorogenic deposits on the Arabian plate (the Red Beds Series) in the NW Zagros orogenic belt in the Kurdistan region of Iraq. Results point to ~26 Ma as a minimum age of collision. In other words, by ~26 Ma, the Neotethys oceanic plate must have been subducted completely between Arabia and Eurasia. The results were published in Geology.

Controls on the thin-skinned versus thick-skinned deformation in the NW Zagros orogenic belt

Based on field observation, balanced cross sections, and apatite (U‐Th)/He thermochronology, I documented that the Zagros fold–thrust belt evolved from a thin–skinned to a hybrid thin‐ and thick‐skinned belt, characterized by a regional out‐of‐sequence basement‐involved shortening during the late Miocene. Such spatial and temporal evolution was influenced by the interplay between basement discontinuities and multi–level mechanically weak stratigraphy, and potentially driven by thermomechanical effects of potential slab breakoff in the rear of the orogen. This research was published in Tectonics.

Impact of fold-thrust belt growth on foreland basin architecture, depositional environment, and sediment dispersal style

In this research, I recognized changes in the depositional environment, stratigraphy, and sediment routing and their provenance through time in the NW Zagros foreland basin. Field and detrital zircon provenance data show that the basin filling was due to an early phase of sediment shedding from distal sources in the eastern Anatolia, and a late phase of sediment arrival from the northwestern Iran. This style of foreland basin filling is unlike the classic model that suggests a change in stratigraphy and sedimentology due to the fold-thrust belt’s gradual advance in a particular direction. The results from this paper highlighted the influence of oblique collision on the foreland basin filling style and argued that the uplift of the sediment source terranes, the Turkish–Iranian plateau, commenced first in the NW and later in the NE. This research was published in Basin Research.

Interplay between shortening, and synorogenic erosion and sedimentation

This work documented for the first time an out-of-sequence thrusting history for the most prominent feature, the Mountain Front Flexure, of the northwestern segment of the Zagros fold-thrust belt in the Kurdistan region of Iraq by utilizing apatite helium thermochronometry, detrital zircon U-Pb geochronology, and basin analysis techniques. The results of this study shed light on the timing and nature of the Cenozoic deformation in the Zagros and discussed potential controls on the pattern of fold-thrust belt advance into the flanking foreland basin, such as variations in syntectonic exhumation, mechanical stratigraphy, and inherited structures. This research was published in Tectonophysics.

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renas.i.koshnaw@gmail.com