White Paper Title: 
Merging reaction path models with spatial and temporal data on ridge systems to predict the timing and location of microbial habitat generation

Reaction path modeling has long been a useful tool in evaluating complex processes in natural systems by quantifying reaction progress. One of the strengths of reaction path modeling is that it is independent of time and space. However, this can be a barrier to relating the results of reaction-path calculations to the spatial and temporal constraints that define natural systems.  The complexities of mapping calculations onto nature are amplified when unraveling biogeochemical processes that involve all of the abiotic and biotic constituents of the system. Nevertheless, overcoming these obstacles will permit new insights not attainable by reaction path modeling alone. Merging model results with observational and geochemical/physical data from Ridge 2000 will also lead to predictions of the timing and location of microbial habitat generation not otherwise possible.

Previous investigations using reaction path modeling reveal only slight differences among MORB alteration assemblages and the resulting fluid compositions regardless of moderate differences in equilibration temperature, or fairly wide ranges of water-to-rock ratios. As examples, calculated pHs, silica activities and hydrogen concentrations are quite similar even when using MORB compositions that span the range of observations.  In contrast, ultramafic assemblages yield far more variability, consistent with experiments and observations of natural systems. In order to understand these systems though, water-rock-microbe interactions and their consequences must be investigated with respect to space and time across the moving reference frame of the ridge system.  To portray these processes in a more tangible way, model results using data from a variety of ridge systems can be presented in the form of affinity diagrams using combinations of reaction progress, time, and composition to deconvolute the biogeochemical processes of the system.  In this way, the conditions of real systems can be mapped spatially and temporally to link the nonequilibrium thermodynamics of water-rock alteration with the nonequilibrium processes of metabolism and biosynthesis.  This approach permits insights into the habitability of diverse geochemical systems as they evolve along/within a ridge segment through both space and time.  The outcome will be new interpretations of the succession of microbial populations as spreading occurs and when linked to temporal data on volcanic events, earthquakes and the subsequent changes in the geochemistry of mineral assemblages and fluids, can aid in predicting habitat generation, sustentation,  evolution, mortality and migration.