Cenozoic diatremes in Chubut, Northern Patagonia, Argentina.

HALLER MJ; NEMETH K

Flagstaff

Taller; Hopi Buttes Volcanic Field Workshop, Maar-Diatreme Volcanism; 2012

University of Otago/Northern Arizona University/USGS

Mafic volcanism in Patagonia started in Paleocene times and continued until the Pleistocene. The Somuncura plateau is the largest (55,000 km2) back-arc mafic volcanic field in South America, and one of Earth?s largest LIPS that has no clear link to a hotspot or major extension. It is possible to recognize a pre-plateau volcanic event of Paleocene-Eocene age, followed by the main eruptive episode which gave origin to the plateau during the Late Oligocene-Early Miocene, and a post-plateau event which lasted until de Late Pliocene [1]. Mafic volcanic fields in the Patagonian region are largely preserved as extensive plateau-like lava fields, strongly eroded scoria cones and lava spatter ramparts. Diatremes have been identified in the deeply eroded parts of former Paleocene volcanoes. Preserved diatremes are eroded to over one hundred meters depth below their original syn-eruptive paleo-surface in some cases. The depth of exposure is estimated to be in the level to exhume deep root zones where the intruding dyke buds mingled, and mixed with the conduit-filling, pyroclast-charged slurry.