Quick
Search: 
   
advanced search
 GSW Home    GeoRef Home    My GSW Alerts    Contact GSW    About GSW    Journals List    Help 

Brief Display | Full Display

P. J. Cook and M. W. McElhinny
A reevaluation of the spatial and temporal distribution of sedimentary phosphate deposits in the light of plate tectonics (in An issue devoted to phosphate, potash, and sulfur)
Economic Geology and the Bulletin of the Society of Economic Geologists (April 1979), 74(2):315-330

Abstract:
A new compilation of paleolatitudes of sedimentary phosphate deposits using worldwide paleomagnetic data confirms the hypothesis that the majority formed at low-latitude locations. A number of Jurassic and possibly some Cambrian deposits formed at intermediate latitudes (30 degrees -50 degrees ). Phosphorites range in age from lower Proterozoic to Recent. There has been sporadic deposition of phosphate during this time, as continents drifted into low-latitude locations. It is proposed that there is no direct genetic link between periods of volcanism, orogenesis, formation of evaporites, and episodes of phosphogenesis. All these features are indirectly genetically related through plate tectonics to particular phases in the rifting and separation of continental and oceanic components of plates. In the case of diverging plates, volcanism and tectonism are an early-stage feature, evaporites intermediate-, and phosphorites late-stage features. Models are developed to explain the different sedimentary sequences that develop in north-south and east-west seaways. No model is presently available for epeiric seas.A temporal model is also proposed to explain the distribution of phosphorus in sediments in the last 3,400 m.y. The association of phosphorus with iron and organic matter in the hydrosphere is particularly critical to the model. Even the temporal model is influenced to some extent by plate tectonics.

Index Terms/Descriptors:
chemically precipitated rocks; continental drift; controls; deposits; distribution; mineral deposits, genesis; paleogeographic controls; paleogeography; paleolatitude; phosphate deposits; phosphate rocks; plate tectonics; resources; sedimentary rocks; spatial variations; time variations

GeoRef, Copyright 2006, American Geological Institute. Abstract, Copyright, Society of Economic Geologists


HOME HELP FEEDBACK SUBSCRIPTIONS SEARCH
Copyright © 1979 by the GeoScienceWorld.