Stratigraphy and sedimentology of South American foreland basin lakes: Keys to deciphering climatic and tectonic controls on lacustrine deposition in ancient foreland basins

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AbstractResearch would produce an understanding of topographic closure, lake/wetland evolution, and lacustrine stratigraphic architecture associated with foreland basins. Results would include the first comprehensive models of modern foreland basin lakes and test the hypotheses of related basin evolution. 3D modeling would be used to test interpretations of other ancient foreland basins providing a means to transport results to other projects. Prior results exemplify a very capable team.Broader impact:Two Ph.D.s and several undergrads. International linkage with sister programs, collaborators, and students in Argentina and Brazil. Results also disseminated to public and paleoclimatology community and biologists studying speciation in foreland basin watersheds.Strengths:Studies of modern and ancient lakes have become common as geologists recognize them as recorders of climate and non-marine life. However, few scientists have focused on understanding the tectonic influence on lake system evolution. This is a much-needed study! Excellent team and collaborators including expertise in paleolimnology, tectonics, geophysics, stratigraphic modeling, and local expertise. Excellent review and plan. Prior experience in handling a synthesis project on lake deposits is evident. Good use of GIS synthesis and SRTM imagery for high resolution geomorphic characterization. Excellent sedimentologic and stratigraphic approach, including utilization of hierarchical sequence stratigraphy that is closely linked to process and grid/stratified sampling design for sedimentologic and facies studies.Work is exciting and addresses an important, fundamental problem. Study provides an integrated approach to better understand topographic closure, lake and wetland evolution, and lacustrine stratigraphic architecture in association with foreland basin, in a similar level of detail as their successful studies of rift valley lacustrine settings. Model input includes multiscaled sampling, coring, and seismic. 3D stratigraphic simulation is quite robust, handling input of 3D structural flexure, erosion and deposition, bed aggradation and degradation, all solved simultaneously. This is an excellent use for computer simulation to extend results of this work to other areas and for use in the classroom.Weaknesses:Panel asks what role the chemical sediments in these lakes play in this study. Recent studies on the saline lakes in the Andean region shows that individual lakes can change greatly both physically and chemically over various short time periods. Evaporites can accumulate quickly and, just as easily dissolve quickly, so their accumulation rates cannot be directly related to time. In addition, these hypersaline lakes change greatly on seasonal and decadal scales. One visit to one of these lakes does not allow a good characterization of it. Will the PIs consult with someone who has studied these hypersaline Andean lakes in detail? Such publications were not cited.Panel expressed concern about the quantification of organic burial rates to be integrated with sediment accumulate rates, which are being measured on very different scales. The 75 carbon analyses currently requested are only one days lab work. Panel suggests the budget be increased for this analytical work. Also, panel requests that PIs ensure that results are not overgeneralized, realizing that the sampling regime must be placed in the context of the dynamic conditions of these lakes. The panel would also encourage the PIs to include one very small lake to be included in their study so that their work is not biased towards medium - large lakes.In general, the proposal is quite ambitious. The panel is concerned that the PIs will not be able to study each lake in enough detail to best understand it.Outcome of this work could have a high impact for a little known depositional system.