Assessing the Role of Crustal Components in the Geochemical Evolution of Arc Magmatism across Eastern Panama and the Colombian Arc
Abstract
The Western and Central Cordilleras of Colombia and the mountains of eastern Panama are composed of a complex collage of terranes which today host some of the world's most dangerous volcanoes. Numerous oceanic terranes have been accreted to the continental margin since the mid-Cretaceous. These are a mixture of intra-oceanic arc and oceanic plateau rocks with related metamorphic and sedimentary components, which now form much of the basement of western Colombia. The basement of eastern Panama in contrast is thought to be a SW extension of the Caribbean oceanic plateau. Recent advances in our understanding of arc magmatism highlight the role of fractionation and assimilation processes in the lower continental crust of continental arcs. For the first time, we present major and trace element and Sr-Nd-Hf isotopic data of Eocene to Recent magmatism from both eastern Panama and western Colombia to assess the role of accreted oceanic terranes in the formation of arc magmas across the region. This includes data from polygenetic and monogenetic edifices of the modern arc, the ancestral sequences of these edifices and hypabyssal and volcanic samples of preceding arc segments in Colombia and Panama of Oligocene to Plio-Pleistocene age. This data is compared to a large dataset of volcanic and hypabyssal rocks of comparable age from the region and analyses of regional basement. This is used to assess the role of crustal contamination and assimilation of oceanic basement, and fractionation processes within the crust, in the production of magmas from the Miocene through to the inception of the modern volcanic arc in Colombia. This demonstrates a greater potential relationship between assimilation of lower and upper crustal material in the petrogenesis of arc magmas in the region than previously assumed, allowing us to test as yet unreconciled local models of andesite and adakite petrogenesis on a regional scale.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T21E0340C
- Keywords:
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- 1099 General or miscellaneous;
- GEOCHEMISTRY;
- 1199 General or miscellaneous;
- GEOCHRONOLOGY;
- 8199 General or miscellaneous;
- TECTONOPHYSICS;
- 8499 General or miscellaneous;
- VOLCANOLOGY