Physics
Scientific paper
Sep 1978
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1978e%26psl..41...32b&link_type=abstract
Earth and Planetary Science Letters, Volume 41, Issue 1, p. 32-46.
Physics
9
Scientific paper
A broad zone of dominantly subaerial silicic volcanism associated with regional extensional faulting developed in southern South America during the Middle Jurassic, contemporaneously with the initiation of plutonism along the present Pacific continental margin. Stratigraphic variations observed in cross sections through the silicic Jurassic volcanics along the Pacific margin of southernmost South America indicate that this region of the rift zone developed as volcanism continued during faulting, subsidence and marine innundation. A deep, fault-bounded submarine trough formed near the Pacific margin of the southern part of the volcano-tectonic rift zone during the Late Jurassic. Tholeiitic magma intruded within the trough formed the mafic portion of the floor of this down-faulted basin. During the Early Cretaceous this basin separated an active calc-alkaline volcanic arc, founded on a sliver of continental crust, from the then volcanically quiescent South American continent. Geochemical data suggest that the Jurassic silicic volcanics along the Pacific margin of the volcano-tectonic rift zone were derived by crustal anatexis. Mafic lavas and sills which occur within the silicic volcanics have geochemical affinities with both the tholeiitic basalts forming the ophiolitic lenses which are the remnants of the mafic part of the back-arc basin floor, and also the calc-alkaline rocks of the adjacent Patagonian batholith and their flanking lavas which represent the eroded late Mesozoic calc-alkaline volcanic arc. The source of these tholeiitic and calc-alkaline igneous rocks was partially melted upper mantle material. The igneous and tectonic processes responsible for the development of the volcano-tectonic rift zone and the subsequent back-arc basin are attributed to diapirism in the upper mantle beneath southern South America. The tectonic setting and sequence of igneous and tectonic events suggest that diapirism may have been initiated in response to subduction. Present address: University of the Witwatersrand, Jan Smuts Avenue, Johannesburg 2001, South Africa.
Bruhn Ronald L.
de Wit Maarten J.
Stern Charles R.
No associations
LandOfFree
Field and geochemical data bearing on the development of a mesozoic volcano-tectonic rift zone and back-arc basin in southernmost South America does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Field and geochemical data bearing on the development of a mesozoic volcano-tectonic rift zone and back-arc basin in southernmost South America, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Field and geochemical data bearing on the development of a mesozoic volcano-tectonic rift zone and back-arc basin in southernmost South America will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-941297