Changes in crustal fluid flow over geologic time

摘要

Important changes in the physical drives for crustal fluid flow may have occurred when substantial organic matter began to be buried in post-Proterozoic time,when continental glaciers grew and melted,and when continents assembled or broke up.The 3.74 Ga Amitsoq gneiss in Quilangarssuit Greenland,that is composed of metamorphosed volca-nics and sediments that include banded ironstones and conglomerates,indicates that the basic physical causes of crustal fluid flow(the hydrologic cycle,gravity-driven flow,sedimentation and compaction,and convection near igneous intrusions)have been in place since the very earliest times.