Mode of formation of an earliest Pliocene — Latest Miocene, basaltic, pillow-lava pile present at Pentecost island, new Hebrides, and its bearing on the formation of basaltic rudite

Bulletin Volcanologique - Tập 43 - Trang 505-510 - 1980
G. Neef1
1W.S. & L.B. Robinson University College, (University of New South Wales), N.S.W., Australia

Tóm tắt

A well exposed, gently tilted, 400 m-high, earliest Pliocene-Latest Miocene, basaltic, pillow-lava pile in Northern Pentecost, New Hebrides contains two large rafts of sediment. These rafts are considered to be important in unravelling how such deep water, pillow-lavapiles develop. It is thought that after early laccolithic intrusion beneath a sediment cover, possibly only 10 m thick, that lava bulged the overlying sediment upwards budding off pillows at localities where upward bulging had created voids. Subsequently, when the pile was probably 100–150 m high, pillow lava was deposited on the upper slopes of the pile from a dyke-feeder. There was, then, two stages of development: an early stage of internal growth and a late stage of external growth. Pillow fragmentation is not necessarily due to gravitational collapse on the exterior of the pile as the bulging-up-process beneath early formed pillows may lead to breccia formation. Deep sea rudites, thus, are considered to be due to autoclastic processes and/or gravitational collapse.

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Tài liệu tham khảo

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Bulletin Volcanologique

Tập 43

505-510

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