Late Neogene Radiolarian Assemblages Characteristic of Indo-Pacific Areas of Upwelling

Abstract

Comparison of radiolarian faunas in Late Neogene sediments from the Peru margin, the Oman margin and from beneath the Somalian gyres allowed definition of an assemblage characteristic of areas of upwelling. We describe the stratigraphic and geographic ranges of 12 previously studied and 10 new or newly described taxa. These forms fall into 3 categories: (1) endemic upwelling (14 species); (2) displaced temperate (3 species); and (3) enhanced tropical (5 species). Not all elements of the assemblage are present, or in like abundances, in each upwelling area studied, but there is sufficient matching to allow identification of the assemblage. Eight long ranging species exhibit diachronous first appearances up to 7 my older in the Oman material than in the Peru material.