[Eoas-seminar] Dr. Guo Jan 30 Seminar 3pm

[eoas-seminar at lists.fsu.edu]

I am pleased to announce a colloquium

On: Friday Jan 30 at 3:00pm

By: Dr. Hongcheng Guo
Purdue University

At: EOAS 1050

Title:
>From Noble Gases to Mountain Ranges: Using Thermochronology to Understand Rock Thermal Histories and Tectonic Processes
Abstract: Understanding the growth and erosion of mountain ranges provides a key framework for a wide variety of natural processes in the lithosphere, at Earth’s surface, and in the atmosphere, as well as their interactions. In this talk, I introduce the use and recent advances in thermochronology for the study of rock thermal histories and the exhumation of mountain ranges, with an emphasis on apatite (U–Th)/He dating.
I begin with the fundamental basis of thermochronology and introduce a community-wide challenge, the overdispersion of (U–Th)/He ages, because of an incomplete understanding of helium diffusion systematics. I then demonstrate the outcomes and new research opportunities stem from the development, testing, and application of a new analytical method, continuous ramped heating (CRH), designed to address this challenge.
(1) Testing CRH on rock samples with well-constrained tectonic and thermal histories shows that CRH can be used as a screening tool for routine (U–Th)/He dating and can reveal first-order kinetic variations in helium diffusion. (2) As a screening tool, CRH is successfully applied to learn the timing of uplift-related exhumation in the intracontinental Altai Mountains, where the exhumation history has traditionally been difficult to constrain. (3) CRH analyses of various samples have shown complex diffusion behaviors of He that are inconsistent with classic volume-diffusion models. This observation motivates a “diffusion sink” hypothesis to explain the complex diffusion, and my most recent work demonstrates that the trapping and release of helium into and out of these diffusion sinks are temperature sensitive and can provide additional information of thermal histories.




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