Quartz as Monitor for Sediment Provenance from Source to Sink (2019-2023, FWF 33038)
Quartz belongs to the most abundant minerals in the Earth’s crust and is an important constituent of sediments and sedimentary rocks. In recent years it has become evident that the incorporation of trace amounts of protons (so called OH defects) reflect initial crystallization conditions and/or later thermal overprint. OH defects and trace metals in quartz allow discrimination between grains from different source rock systems, such as those from young igneous bodies versus those from bodies with metamorphic overprint. Mineral and melt inclusions reflect the crystallization history of quartz, too, but are more inert towards thermal treatment than OH defects. Knowing both characteristics (OH defects and melt/mineral inclusions) allows for the reconstruction of initial crystallization condition and later metamorphic overprint of individual quartz grains. In this way, individual quartz grains bear a wealth of information concerning their geological history and have a high potential as a tracer that may be used to determine sediment provenance and infer geological processes within the source area, even if the respective parent rocks have long been eroded away.
The “quartz-monitor” research project investigates the intrinsic chemical variations of detrital monocrystalline quartz and inclusions (mineral and melt) as an innovative sediment provenance tool. The aim of this project is to generate the first comprehensive database of detailed OH defect characteristics of detrital quartz from selected sedimentary systems with properties that make them model systems for other localities worldwide, and to test applicability and limits of hydrous defects and trace metal geochemistry in quartz as a monitor for sedimentary processes and provenance analysis in large-scale source to sink settings. The sample material will be derived from existing offshore wells drilled by international scientific ocean drilling, ongoing IODP expeditions and on-shore reference material. As main analytical methods Fourier-Transform Infrared (FTIR) Spectroscopy, Secondary Ion Mass Spectrometry (SIMS), and Electron Probe Micro Analyzer (EPMA) will be used.
Results of this project will help to further understand the evolution of different contributors in large sedimentary systems in terms of provenance and mixing ratios of quartz from different lithologies (metamorphic, igneous, and reworked sedimentary material), as quartz populations better reflect mixing ratios of contributing sources than accessories such as heavy minerals, or zircon age spectra.
Publications:
Stalder, R. (2021): OH point defects in quartz – a review. European Journal of Mineralogy 33, 145-163