Dating South African Rifting Events via Apatite Helium Thermochronology
Additional Funding Sources
This project is supported by a 2019-2020 STEM Undergraduate Research Grant from the Higher Education Research Council.
Abstract
Despite many years of study the topographic evolution of the south African plateau is still poorly understood. Thermal histories and cooling dates obtained from rocks that compose the area may give an idea to the progression of continental rifting and plateau development. Our goal is to constrain the < 70°C thermal history from samples in the Algoa and Gamtoos basin using (U-Th)/He Thermochronology dating. We began the process to acquire the data necessary by selectively picking and packing apatite grains that meet several quality requirements. 64 apatite grains from 13 sedimentary rock samples have been selected for analysis packaged and sent to the University of Colorado Thermochronology Research and Instrumentation Laboratory (CU TRaIL) to be analyzed. After analysis we will examine our data for spatial patterns using Geographic Information System (GIS) software. In addition a forward and inverse thermal history models will be conducted using a software called HeFTy (Ketcham 2005). This software will allow for the exploration of thermal histories that can explain data well while taking into consideration of other geologic information and previously published geo- and thermochronology from the region that constrain the possible histories. Preliminary cooling dates for samples 1059-61 and 1059-62 are 90 ± 11 and 103 ± 14 Ma. These dates are substantially younger than the depositional ages for the samples and rifting in the region. Theses dates would suggest a major cooling phase 90 – 100 Ma that may be associated with plateau development.
Dating South African Rifting Events via Apatite Helium Thermochronology
Despite many years of study the topographic evolution of the south African plateau is still poorly understood. Thermal histories and cooling dates obtained from rocks that compose the area may give an idea to the progression of continental rifting and plateau development. Our goal is to constrain the < 70°C thermal history from samples in the Algoa and Gamtoos basin using (U-Th)/He Thermochronology dating. We began the process to acquire the data necessary by selectively picking and packing apatite grains that meet several quality requirements. 64 apatite grains from 13 sedimentary rock samples have been selected for analysis packaged and sent to the University of Colorado Thermochronology Research and Instrumentation Laboratory (CU TRaIL) to be analyzed. After analysis we will examine our data for spatial patterns using Geographic Information System (GIS) software. In addition a forward and inverse thermal history models will be conducted using a software called HeFTy (Ketcham 2005). This software will allow for the exploration of thermal histories that can explain data well while taking into consideration of other geologic information and previously published geo- and thermochronology from the region that constrain the possible histories. Preliminary cooling dates for samples 1059-61 and 1059-62 are 90 ± 11 and 103 ± 14 Ma. These dates are substantially younger than the depositional ages for the samples and rifting in the region. Theses dates would suggest a major cooling phase 90 – 100 Ma that may be associated with plateau development.