西南太平洋新喀里多尼亚洛亚蒂盆地的现代沉积作用

洛亚蒂盆地沉积物是棕黄色软泥和生物碎屑砂。它们有5个来源:新喀里多尼亚堤礁、深海生物群落、浮游生物群体和火山碎屑。沉积物由浊流和半深海沉积物的互层组成,可以通过粒度分析,矿物成分和生物碎屑的分析将两者加以区分。通过对蒂奥和利富之间的岩心的研究,认识到在蒂奥水道对面,分布着一个展布广阔,但幅度很小、延伸50km的海底扇。

Modern Sedimentation in the Loyalty Basin Along the Thio-Lifou Profile (New Caledonia,SW Pacific)

The Loyalty Basin, northeast of new Caledonia, is about 100km wide and 2350m deep in the transect between Thio (New Caledonia) and the island of Lifou. It is bounded to the southwest by New Caledonia and its surrounding barrier reef and to the northeast by the barrier reef of the Loyalty Ridge. Lifou Island, a raised atoll, is an emerged part of the Loyalty Ridge. The sediments cored in the Loyalty Basin during the BIOCAL mission is 1985 are bioturbated and composed of an alternation of turbidites and hemipelagites. The hemipelagites are brownyellowish muddy oozes to calcareous muds; the turbidites are composed of sandy and silty oozes capped transitionally with muddy oozes. The hemipelagite and the Te division of the Bouma sequence have different characteristics but are not located in the core. However, they can be distinguished by carbonate composition and grain size. All the sediments originate from five sources: (1) New Caledonia (quartz, clay and heavy minerals), (2) the barrier reef (fragments of algae, madreporarian corals, foraminifera and mud of the periplatform, (3) plankton (foraminifera, coccoliths and pteropoda), (4) the bathyal community and (5) pyroclastic fragments. Turbidites, distributed in cores between Thio and Lifou, constitute a low-profile submarine fan fed by the main canyons of the slope opposite the Thio Pass. The fan developed from a rim of slumps and mud flows located near the base of the slope. The fan extends 50km toward the northeast as far as the tectonic Levi Ridge. The hemipelagites are predominant beyond this ridge.