UPPER PALEOZOIC AND LOWER MESOZOIC RADIOLARIAN ASSEMBLAGES FROM THE BUSUANGA ISLANDS, NORTH PALAWAN BLOCK, PHILIPPINES

菲律賓北巴拉灣地塊布西安哥群島上部古生代與下部中生代放射蟲族群之研究

程延年(YEN-NIEN CHENG)

《Collection and Research》 1期 (1989/09) Pp. 129-175

https://doi.org/10.6693/CAR.1989.1.7

摘要

A preliminary field sampling from ribbon chert successions on Busuanga and UsonIs lands yield abundant and well-preserved Radiolaria. Six radiolarian assemblages can be recognized of which three assemblages are of Permian in age and three assemblages are of Triassic in age. They are tentatively named as: Albaillella cf. levis-Latentifustula cf. similicutis Assemblage, Follicucullus cf. scholasticus-Triplanospongos cf. musashiensis Assemblage, Neoalbaillella cf. optima Assemblage, Pesudoheliodiscus sp. F Assemblage, and Betraccium deweveri Assemblage. Twenty-nine species belongingto thirteen genera of the Upper Paleozoic albaillellids and stauraxon polycystins are illustrated. For Triassic (Ladinian to upper Norian) section, Radiolaria are much more diversified and totally sixty-four species belonging to twenty-three genera are illustrated.

並列摘要

本論文分析採自菲律賓北巴拉灣地塊，布西安哥群島(Busuanga Islands)燧石層中之上部古生代與下部中生代放射蟲族群。根據初步研究結果，該燧石層中保存良好之放射蟲可分為六個明顯之族群組合，其中三個屬於二疊紀，三個歸屬於三疊紀。本研究之初步結果具有下列三項重要意義：(1)晚古生代與早期中生代深海相燧石層中之放射蟲在全球分佈極為有限，尤其通過古/中生代界限(P／T boundary)，放射蟲族群有顯著之變異，呈現截然不同之面貌。本研究剖面可提供接近連續之放射蟲組合變化，得以對放射蟲演化趨勢做進一步探討;(2)二疊紀與三疊紀合放射蟲之燧石層隱約指示該區域與南中國海張開形成之前的古地中海(Paleo-Tethys)有關。北巴拉灣地塊是否為古地中海經由中國南域向東延伸之存留殘體，值得進一步探討;(3)環西太平洋島弧自日本、琉球(臺灣)、巴拉灣至波羅洲一系列的晚古生代一早中生代地層，表現極為類似的混同層(melange)岩性結構，進一步對放射蟲之研究將有助於對該區域地質史之瞭解。本論文描繪了上部古生代二壘13屬、29種，以及下部中生代三疊紀23屬、64種的放射蟲，其精確之分類學研究正進行中，將另行發表。