CURRENT & FUTURE RESEARCH INTERESTS

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CURRENT FOCUS... FINISH DISSERTATION!

TITLE: Tracking the low-temperature thermal evolution of the Bundelkhand craton and Vindhyan basin

Associated manuscripts in preparation:

  • Temporal insight into the stabilization, unroofing, and subsequent burial of the Bundelkhand craton of central India

  • Deccan traps thermal overprint on zircon and apatite (U-Th)/He dates from the Bundelkhand craton and Vindhyan basin of Central India

SUMMARY:

This work utilizes a suite of geo- and thermochronometric tools, coupled with detailed stratigraphic analysis, to unravel the long-term burial and erosional evolution of central India from 2.5 Ga to the present. This works pairs detrital zircon U-Pb ages from the Vindhyan basin with apatite U-Pb ages from the Bundelkhand craton to reveal the craton's evolution from ~2.5 to ~950 Ma. To unravel the low-temperature thermal evolution of the Bundelkhand craton from ~1 Ga to the present, this study uses the radiation damage accumulation and annealing models for the zircon and apatite (U-Th)/He system. This work provides new insight into (1) processes leading to craton stability, (2) current limitations in modelling long-term low-temperature thermal histories,  and (3) mechanisms controlling erosion of quiescent continental interiors.

INTERESTS FOR NOW AND LATER...

  • Was a discrete global-scale erosional event(s) necessary for the "Cambrian Explosion" to occur?  If so, what are the driving mechanisms?

  • Do long-term thermal histories from quiescent cratons across the globe share similarities?

  • Can radiation damage accumulation and annealing models for the (U-Th)/He system account for subtle, short-lived heat pulses?

  • How can we reliably track rates of sediment recycling within surficial and deep crustal environments throughout deep time?

Himalayan related:

  • How can we more reliably distinguish between Kohistan-Ladakh and Gangdese arc derived sediment in early Eocene Himalayan deposits?

  • What are the spatial-temporal kinematic relationships between iLH duplexes, the Munsiari thrust, and the MCT? What is driving along strike variability, and are these kinematic relationships linked to spatial-temporal patterns in crustal exhumation?

IF YOU SHARE ANY INTERESTS OR WOULD LIKE TO DISCUSS ANY OF THE ABOVE, PLEASE FEEL FREE TO CONTACT ME—I'M ALWAYS HAPPY TO CHAT.

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Sediment provenance of pre- and post-collisional Cretaceous–Paleogene strata from the frontal Himalaya of northwest India

Colleps, C.L., McKenzie, N.R., Horton, B.K., Webb, A.A.G., Ng, Y.W., Singh, B.P.

2020 Earth and Planetary Science Letters

ABSTRACT:

Whereas the timing for India–Asia collision remains debated, contrasting collisional models provide testable predictions in terms of sediment source contributions during the accumulation of Paleocene to middle Eocene deposits now exposed in the frontal Himalayan system. Within the Lesser Himalaya and frontal thrust system of northwest India, discontinuous exposures of the Cretaceous Singtali Formation and upper Paleocene–middle Eocene Subathu Formation yield a record of these early collisional stages. To test competing collisional models, we analyze the provenance of these deposits with new detrital zircon U-Pb and Hf isotopic data which can distinguish among Indian plate, Asian plate, Kohistan-Ladahk arc, and various Himalayan sources. Detrital zircon age distributions for the Singtali Formation are dominated by Paleoproterozoic zircons with a distinct Cretaceous age component, whereas age data from the Subathu Formation record (1) a marked increase in the relative abundance of Cambrian–Neoproterozoic grains, (2) a decrease in the proportion of Paleoproterozoic grains, and (3) distinct Permian and Late Cretaceous–Paleocene age components. All Cretaceous grains from the Singtali Formation yielded crustal Hf isotopic signatures, indicating a distinctive pre-collisional source of Cretaceous grains of Indian affinity. Zircon Hf isotopic signatures from <320 Ma grains in the Subathu Formation show a significant lower to middle Eocene increase in source diversity, including juvenile grains most likely originating from the Asian plate and Kohistan-Ladakh arc. This requires inception of India-Asia collision by ∼44–50 Ma—the depositional age of the uppermost Subathu Formation. This major provenance shift is similar to that observed for pre- and post-collisional Tethyan Himalayan strata in the north, which is suggestive of a single contiguous basin linking the Lesser Himalaya by ∼44–50 Ma and contests the notion that the Lesser and Tethyan Himalaya were separated by a “Greater India Basin” during the Eocene. When coupled with the well documented Paleocene–early Eocene provenance record of the Tethyan Himalaya, these new data provide support for a collisional model in which Asian detritus reached the northernmost edge of India by ∼59 Ma with terminal closure of both the Shyok and Indus-Yarlung suture zones by ∼54 Ma.

https://doi.org/10.1016/j.epsl.2020.116079

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Neogene Kinematic Evolution and Exhumation of the NW India Himalaya: Zircon Geo‐ and Thermochronometric Insights From the Fold‐Thrust Belt and Foreland Basin

Colleps, C.L., Stockli, D.F., McKenzie, N.R., Webb, A.A.G., Horton, B.K.

2019 Tectonics

ABSTRACT:

The kinematic and exhumational evolution of the Lesser Himalaya (LH) remains a topic of debate. In NW India, the stratigraphically diverse LH is separated into the inner LH (iLH) of late Paleo‐Mesoproterozoic rocks and the outer LH (oLH) of Cryogenian to Cambrian rocks. Contradictory models regarding the age and structural affinity of the Tons thrust—a prominent structure bounding the oLH and iLH—are grounded in conflicting positions of the oLH prior to Himalayan orogenesis. This study presents new zircon (U‐Th)/He and U‐Pb ages from the thrust belt and foreland basin of NW India that refine the kinematic and exhumational evolution of the LH. Combined cooling ages and foreland provenance data support emplacement and unroofing of the oLH via southward in‐sequence propagation of the Tons thrust by middle Miocene time. This requires that, before India–Asia collision, the oLH was positioned as the southernmost succession of Neoproterozoic–Cambrian strata along the north Indian margin. This is further supported by detrital zircon U‐Pb ages from Cretaceous–Paleogene strata (Singtali Formation) unconformably overlying the oLH, which yield diagnostic Cretaceous detrital zircons correlative with coeval strata in the frontal Himalaya of Nepal. A pulse of rapid exhumation along the Tons thrust front at ~16 Ma was followed by east‐to‐west development of a midcrustal ramp at ~12 Ma which facilitated diachronous iLH duplexing. This duplexing shifted the locus of maximum exhumation northward, eroding away Main Central Thrust hanging wall rocks until the iLH breached the surface at ~9–11 Ma near Nepal and by ~3–7 Ma within the Kullu‐Rampur window.

https://doi.org/10.1029/2018TC005304

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Zircon (U‐Th)/He Thermochronometric Constraints on Himalayan Thrust Belt Exhumation, Bedrock Weathering, and Cenozoic Seawater Chemistry

Colleps, C.L., McKenzie, N.R., Stockli, D.F., Hughes, N.C., Singh, B.P.,  Webb, A.A.G., Myrow, P.M., Planavsky, N.J., Horton, B.K.

2018 Geochemistry, Geophysics, Geosystems

ABSTRACT:

Shifts in global seawater 187Os/188Os and 87Sr/86Sr are often utilized as proxies to track global weathering processes responsible for CO2 fluctuations in Earth history, particularly climatic cooling during the Cenozoic. It has been proposed, however, that these isotopic records instead reflect the weathering of chemically distinctive Himalayan lithologies exposed at the surface. We present new zircon (U‐Th)/He thermochronometric and detrital zircon U‐Pb geochronologic evidence from the Himalaya of northwest India to explore these contrasting interpretations concerning the driving mechanisms responsible for these seawater records. Our data demonstrate in‐sequence southward thrust propagation with rapid exhumation of Lesser Himalayan strata enriched in labile 187Os and relatively less in radiogenic 87Sr at ∼16 Ma, which directly corresponds with coeval shifts in seawater 187Os/188Os and 87Sr/86Sr. Results presented here provide substantial evidence that the onset of exhumation of 187Os‐enriched Lesser Himalayan strata could have significantly impacted the marine 187Os/188Os record at 16 Ma. These results support the hypothesis that regional weathering of isotopically unique source rocks can drive seawater records independently from shifts in global‐scale weathering rates, hindering the utility of these records as reliable proxies to track global weathering processes and climate in deep geologic time.

https://doi.org/10.1002/2017GC007191