Lake-basin-types 2.0?expanding the model to the 4th dimension? and beyond!

MANCUSO, ADRIANA CECILIA; BOHACS, KEVIN; BENAVENTE, CECILIA ANDREA; CARROL, ALAN

Seattle

Congreso; GSA annual Meeting; 2017

The lake-basin-type model of Carroll and Bohacs (1999) classified the stratigraphic record of ancient lakesystems according to rates of potential accommodation relative to sediment+water supply. To provide widespreadapplicability, the model convolved all modes and paths of water supply (direct fall, surficial, subsurface) withamounts and types of sediment supply (clastic, biogenic, chemical) into a single basin-filling volume term(sediment+water). Subsequent investigations confirmed the utility of this approach and widened its applicationbeyond lake C cycles and resource evaluation to biological evolution and HC reservoirs, but also revealed someimportant limitations due to simplifications in the original model.We propose adding two major subdivisions of the sediment+water term: 1) water-supply paths and 2) the volumeof water supply relative to sediment supply.Water-supply paths are categorized as ?through-flow? (for overfilled, balanced-fill, and underfilled lake-basintypes), ?recharge? (for balanced-fill and underfilled), and ?discharge? (for underfilled) using Rosen?s 1994approach. These paths can be deciphered using stable carbonate and oxygen isotope composition of primarylacustrine limestones, detailed sedimentology, and mineralogy. Distinguishing water-supply paths providesadditional insights into playa systems and character of evaporite and carbonate strata.The ratio of sediment and water volumes most directly influences the depth of lake waters which affect lakehydrodynamics and ecosystem behavior as well as the details of stratal stacking and depositional sequences. Ithelps fine-tune estimates of the distribution of porosity, permeability, and organic-matter content.These additions can aid more detailed interpretations of lacustrine strata, understanding controls onbiogeochemical cycles, and predicting the occurrence and distribution of various chemical species, but they are ahypothesis to be tested. The evolution of these lake models benefitted from being embraced by the limnogeologycommunity (due to the work of such champions as Beth Gierlowki-Kordesch and her students). It showed thebenefit of having relatively simple, but broadly applicable frameworks based on objective observations, to focusdiscussion and move a discipline forward.