Japan Geoscience Union Meeting 2016

Presentation information


Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG56] Petrology, Mineralogy and Resource Geology

Thu. May 26, 2016 3:30 PM - 4:45 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Tatsuo Nozaki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Akira Miyake(Department of Geology and Mineralogy, Graduate School of Science, Kyoto University), Nobutaka Tsuchiya(Department of Geology, Faculty of Education, Iwate University), Satoshi SAITO(Graduate School of Science and Engineering, Ehime University)

3:30 PM - 4:45 PM

[SCG56-P08] Petrological feature of Nakanodake intrusion from Yoneyama area, northern Fossa Magna, Central Japan

*Masataka Aizawa1, Takaharu Sato2, Satoshi Okamura1, Yoneyama Research Group (1.Hokkaido Education University, Sapporo Campus, 2.Osaka Museum of Natural History)

Keywords:Northern Fossa Magna, Yoneyama, Nakanodake intrusion, Crystallization differentiation, Tholeiitic rock series

Early Pleistocene Nakanodake intrusion, 1.2-1.6 km diameter, is located in northern Fossa Magna. The intrusion, composed of inner gabbro and outer hornblende andesite, is intruded in the Yoneyama Formation. On the basis of petrography and geochemistry, the intrusion is divided into Opx-Cpx gabbro, Hor-Opx-Cpx andesite, and Hor-Cpx andesite. The rocks of the Nakanodake intrusion have high K content and tholeiitic characteristics, indicating a similar geochemical trend to that of the Yoneyama Formation. Mg value (100*Mg/(Mg+Fe)) of Opx and Cpx, and An content of plagioclase in gabbros are lower than those in hornblende andesites, which suggests that the rocks from the intrusion were not originated by fractional crystallization from the common source magma.