RESEARCH Geochemistry and Geochronology
RESEARCH Geochemistry and geochronology of the Troodos ophiolite: An SSZ ophiolite generated by subduction initiation and an extended episode of ridge subduction? Soichi Osozawa1,*, Ryuichi Shinjo2, Ching-Hua Lo3, Bor-ming Jahn3, Nguyen Hoang4, Minoru Sasaki5, Ken’ichi Ishikawa6, Harumasa Kano7, Hiroyuki Hoshi8, Costas Xenophontos9, and John Wakabayashi10 1DEPARTMENT OF EARTH SCIENCES, GRADUATE SCHOOL OF SCIENCE, TOHOKU UNIVERSITY, SENDAI 980-8578, JAPAN 2DEPARTMENT OF PHYSICS AND EARTH SCIENCES, UNIVERSITY OF THE RYUKYUS, NISHIHARA 903-0213, JAPAN 3DEPARTMENT OF GEOSCIENCES, NATIONAL TAIWAN UNIVERSITY, TAIPEI 10699, TAIWAN 4FORMER: GEOLOGICAL SURVEY OF JAPAN, ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY (AIST), TSUKUBA 305-8567, JAPAN 5DEPARTMENT OF EARTH AND ENVIRONMENTAL SCIENCES, GRADUATE SCHOOL SCIENCE AND TECHNOLOGY, HIROSAKI UNIVERSITY, HIROSAKI 036-8561, JAPAN 6CENTER FOR THE ADVANCEMENT OF HIGHER EDUCATION, TOHOKU UNIVERSITY, SENDAI 980-8576, JAPAN 7TOHOKU UNIVERSITY MUSEUM, SENDAI 980-8578, JAPAN 8DEPARTMENT OF EARTH SCIENCES, GRADUATE SCHOOL OF EDUCATION, AICHI UNIVERSITY OF EDUCATION, KARITA 448-8542, JAPAN 9FORMER: CYPRUS GEOLOGICAL SURVEY, NICOSIA 1415, CYPRUS 10DEPARTMENT OF EARTH AND ENVIRONMENTAL SCIENCES, CALIFORNIA STATE UNIVERSITY, FRESNO, FRESNO, CALIFORNIA 93740, USA ABSTRACT New trace-element, radiogenic isotopic, and geochronologic data from the Troodos ophiolite, considered in concert with the large body of previously published data, give new insight into the tectonic history of this storied ophiolite, as well as demonstrating the variability of suprasubduction-zone ophiolites, and differences between them and commonly used modern analogs. Similar to earlier studies, we fi nd that island-arc tholeiite of the lower pillow lava sequence erupted fi rst, followed by boninite. We further divide boninitic rocks into boninite making up the upper pillow lava sequence, and depleted boninites that we consider late infi ll lavas.
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