WORKING GROUP ON SEDIMENT GENERATION
WGSG TECHNICAL SECTIONS
The WGSG aims at broadening the community and favour the debate and the initiative of early-career geoscientists. The subsections exist to create groups of discussion, literature exchange and especially to push the brinstorming sessions during the meetings of the group. Get in touch with one of our coordinators to contribute to the development of both the subsection and the WGSG!
EXHUMATION SECTION
Sediments are mostly generated by the erosion of landforms. The amount of sediments generated is dependent of several factors such as the nature of the bedrock, erosion and uplift rates and climate. Constraining the location, timing, and magnitude of uplift and erosion events allow to better understand the source of sediments deposited in surrounding basins. Several methods exist to quantify exhumation events both on the source terranes and on the sedimentary basins:
- Thermochronology-based methods:
o fission track analyses on apatite (AFT), zircon (ZFT);
o (U-Th-Sm)/He analyses on apatite (AHe), zircon (ZFT);
o cosmogenic nuclides
o clumped isotopes with U/Pb dating (carbonates)
- Other thermal-based methods:
o vitrinite reflectance
- Stratigraphic-based methods:
o unconformity studies
o mass-balance studies
- Tectonic-based methods:
o subsidence curve analysis
- Compaction-based method:
o well & seismic velocity anomalies
EROSION AND TRANSPORT
Weathering and erosion
All sedimentary detritus is derived from weathered parent rock material and is supplied to the routing system through erosion. Bedrock geology, climate and tectonics influence style and rates of weathering and erosion and thus control the texture and the composition of sediments. It is therefore crucial to understand (1) which processes control sediment generation in a variety of geodynamic and climatic settings, (2) how bedrock properties influence sediment properties, and (3) at what rates sediment is produced.
Transport and sorting
The final sedimentary product in a sink almost never reflects the initial provenance of a sediment. While in transit, chemical alteration, mechanical breakdown, hydraulic sorting, sediment recycling and mixing may modify, and in some cases, completely obscure original compositions and textures. By understanding the chemical and physical processes producing this environmental “noise”, valuable information may be deciphered and successfully separated from the initial signal.
DIAGENESIS
The conversion of loose sediments into consolidated rocks is regulated by a number of processes starting after deposition (e.g. compaction, cementation etc.). However, both depositional texture and mineralogy represent the starting conditions which largely regulate post depositional modifications. Initial mineralogical composition (e.g. ductile and unstable grains) and sediment textural fabric (e.g. grain-size and sorting) results, from the interaction of both external forcing (tectonic, climate and lithology) and autogenic controls on sediment generation, partitioning and dispersal and eventually the trajectories of sediment particles and solutes. Furthermore, the interplay of climate and sedimentary environments determines pore-water chemistry which in turn rules the extent and type of weathering and pedogenesis during sediment temporary storage and/or final deposition. Both processes are intimately related to clay production, abundancy and type as well as to its spatial distribution within sedimentary environments and associated facies. This section aims at investigating all the factors controlling the generation of sediment in its broadest sense (as well as those regulating their distribution within the sedimentary system) and their impact on early diagenetic processes.