Explosive deep water basalt in the sumisu backarc rift.

Abstract

Eruption of 1-million-year-old tholeiitic basalt >1800 meters below sea level (>18 megapascals) in a backarc rift behind the Bonin arc produced a scoriaceous breccia similar in some respects to that formed during subaerial eruptions. Explosion of the magma is thought to have produced frothy agglutinate which welded either on the sea floor or in a submarine eruption column. The resulting 135-meter-thick pyroclastic deposit has paleomagnetic inclinations that are random at a scale of <2.5 meters. High magmatic water content, which is about 1.3 percent by weight after vesiculation, contributed to the explosivity.

• Authors: J Gill, P Torssander, H Lapierre, R Taylor, K Kaiho, M Koyama, M Kusakabe, J Aitchison, S Cisowski, K Dadey, K Fujioka, A Klaus, M Lovell, K Marsaglia, P Pezard, B Taylor, K Tazaki
• Journal: Science (New York, N.Y.) (Science) Vol. 248 Issue 4960 Pg. 1214-7 (Jun 08 1990) ISSN: 0036-8075 [Print] United States
• PMID: 17809906 (Publication Type: Journal Article)