The use of regional, but detailed, aeromagnetic data to define the Precambrian basement fault pattern, the plumbing system for mineral concentrations in the lithosphere
Gay, S. Parker Jr.
published: Jan 1, 2003
ArtNo. ESP136000800044, Price: 19.00 €
Hydrothermalists accept as fact the idea that faults in the basement metamorphic complex serve as conduits ("plumbing") for rising magmas and fluids coming from the lower crust and mantle and that these magmas and fluids give rise to ore concentrations by precipitation near the earth's surface. However, the spatial characteristics of the transmissive basement faults are generally not known, nor is there consensus as to their age. Were they formed contemporaneously by the lower density magmatic fluids as they rise, or are they part of a pre-existing pervasive network of basement faults of considerable antiquity? The author hypothesizes that the latter is true and in support of this, will show that basement shear zones/faults have controlled almost all faults that cut the Phanerozoic sedimentary section in cratonic petroleum basins. This is proven by comparing basement fault locations mapped by state-of-the-art aeromagnetic processing and interpretation techniques with the detailed and voluminous subsurface mapping and seismic data generated by the petroleum industry. If this observation holds true for rocks in petroleum basins for the last 500 million years or so, it certainly holds true for hard-rock areas, i.e. the remainder of continental crust during the same time period. By scientific extension, it probably holds true for all continental crust during much, or all, of earth's history. To summarize: earth's crust is cut by a pervasive fracture pattern that formed in Archean or Early Proterozoic time, has been reactivated numerous times since, controls much, or most, later geology, including emplacement of mineral-rich plutons and vein-systems, and is mappable, to large degree, with modern aeromagnetic methods.