Detrital Thermochronology
Introduction
Detrital thermochronology is a method of provenance analysis that directly constrains the age of source rocks by dating individual mineral grains within the sedimentary rock itself. Rather than inferring source lithology from mineral type or optical properties alone, detrital thermochronology yields absolute ages that can be matched to known source terrains. This makes it possible to trace individual grains back to specific source areas - a capability that conventional petrographic provenance methods cannot provide.
Detrital thermochronology involves estimation of the ages of single mineral grains - such as apatite and zircon - using various radiometric techniques. Determining the ages of individual mineral grains in sedimentary rocks provides the ages of the source rocks from which those grains were derived. This analysis makes it possible to link mineral grains to specific source areas of known age. [1]
Why Apatite and Zircon
Zircon and apatite are the most commonly dated minerals in detrital thermochronology for complementary reasons. Zircon is extremely resistant to physical and chemical weathering - it survives multiple sedimentary cycles intact - and its uranium-lead (U-Pb) system has a high closure temperature, recording the crystallisation age of the source rock. Apatite is less resistant but has a lower closure temperature for the fission track and (U-Th)/He systems, which record the cooling history of the source rock and can reveal timing of exhumation and uplift. Together, zircon and apatite provide both crystallisation and cooling ages, giving a fuller picture of source terrain history.
Related Topics
Weathering
Weathering is the physical disintegration and chemical decomposition of older rock that produces solid particulate residues - resistant minerals and rock fragments - and dissolved chemical...
Provenance Analysis
The silicate mineralogy and rock-fragment composition of siliciclastic sedimentary rocks are fundamental properties that set them apart from other sedimentary rocks. Mineralogy is a particularly...
Mineral
"Mineral" means different things depending on who you ask.{/* SRC: Nesse p.3: "Almost every human endeavor is influenced by minerals. Many natural resources used in the manufacture of" */}...
Siliciclastic Sedimentary Rocks
Siliciclastic sedimentary rocks are sedimentary rocks composed mainly of silicate particles derived by the weathering breakdown of older rocks and by pyroclastic volcanism. Sandstones,...
References & Citations
- 1.Principles of Sedimentology and Stratigraphy Boggs, Sam Jr.
Master UPSC Geology Optional
Ex-ONGC Geologist & Rank Holder
Learn the exact analytical answer-writing patterns needed for UPSC Optional from an AIR 2 & AIR 25 holder.
Offline in Delhi