In practice, these adventures involve loading up a research vessel or a large cargo van with equipment and people for an all-out geochemical study of sediments, pore waters in sediments, and overlying waters. In carbonates, the very rapid breakdown of the abundant associated organic matter together with rapid sediment mixing by burrowing organisms leads to massive carbonate dissolution in nearly all sedimentary environments. The dissolution is on a fine scale and is easy to miss with the petrographic microscope. For terrigenous sediments, Walter's group documented chemical shifts in clay minerals from both hypersaline and estuarine environments. These changes are consistent with ion exchange from clay surfaces and clay mineral transformations and suggest that early fixation of K from seawater can lead to early illite formation.
Experiments relate mineral reactions to measurable, observable phenomena.
In EAGL, a controlled experimental approach is taken to mineral growth and dissolution rates by direct measurement in known solution chemistries, at different reaction times and temperatures. Walter s group is currently determining reaction rates for feldspar alteration, quartz precipitation and salt recrystallization. Fluid salinity and organic acid content have major roles in the rate of feldspar dissolution as well as in the formation rate of secondary clay minerals. Quartz precipitation is more rapid as the fluid salinity increases. These experiment results can be related back to rock products and burial histories resulting is a useful blend of chemistry with geologic factors to better explain natural reservoir porosity and permeability.