Re-evaluation of Infiltration-driven Regional Metamorphism in Northern New England: New Transport Models with Solid Solution and Cross-layer Equilibration of Fluid Composition

摘要: The spatial distribution of reactants and products infiltrationdriven decarbonation reactions can be a record the geometry amount reactive fluid flow during regional metamorphism. In past, these distributions have been interpreted assuming (1) minerals are fixed in composition (2) single layers chemically isolated. Because neither assumption is normally valid, new transport models were developed that specifically predict well-studied biotite-forming reaction marls from northern New England.The consider isothermal isobaric (iso-P^T) flow, horizontal direction increasing T (up-T flow), (3) vertical, upward decreasing P andT (down-P^T flow). All assume medium composed many thin differ amounts compositions mineral solid solutions prior to reaction, parallel layering, homogenized across layering over distance much greater than layer thickness. reproduce at outcrops Maine Vermont where there extensive data, regional-scale observations only low grades region several kilometers wide higher grade coexist. Models up-T down-P^T preferred because they additionally spatially widespread complete highest grades. Results show when solutions, predicted by simple hydrodynamic metamorphic fully consistent with observed terrains. further demonstrate layer-scale variations progress better explained terms layer-by-layer initial abundances coupled homogenization channelized focused into elevated progress. minimum time-integrated fluxes 10mol cm 2 rock, 1^2 orders magnitude less what has estimated composition.