Miocene Radiolarian Faunas from Southern California

Abstract

The Radiolaria described in this paper came from tw o areas in southern California, the Palos Verdes Hills and the Newport area. M ost of these deposits consist of or ganic shales referred to as the M onterey shale. In the Palos Verdes Hills the deposits are about 2500 feet thick and have been divided into five lithologic members. Three are named (beginning at the base) the Altam ira shale, the Valmonte diatom ite, and the M alaga mudstone. Radiolaria were abundant in the latter two members. M ost of the Newport area samples studied contain a very large proportion of species com m on to the Valmonte member of the Palos Verdes Hills. The writers conclude that the shales containing the Radiolaria of the Palos Verdes Hills and New port area were laid down under conditions not greatly dissimilar to those existing in the adjacent Catalina Channel under open sea conditions; and that at least the upper portion of the M alaga mudstone is almost certainly bathyal, although possibly other portions were deposited under shallower water conditions. N inety-one species, all of them new, are herein described. INTRODUCTION AND ACKNOWLEDGMENTSSeveral years ago the writers' attention was called to the occurrence of Radiolaria at a number of Miocene localities in southern California. Woodring, Bramlette, and Kleinpell (1936), in describing the geology of the Palos Verdes Hills, noted that radiolarians were abundant in a number of their localities. The writers, through the courtesy of the late Dr. R. D . Reed, at that time chief geologist of the Texas Oil Company, obtained samples of the shales from the localities referred to in that paper, as well as a considerable number of other samples, including several from the Newport Bay area, a few miles to the southeast. Most of these samples yielded well-preserved radiolarians, described in this paper, the first from the marine Miocene of Western North America.ABSTRACT 2 MIOCENE RADIOLARIAN FAUNAS FROM SOUTHERN CALIFORNIA " The M onterey shale has an estimated thickness of 2500 feet in the Palos Verdes Hills, and the base is not exposed in the region where the oldest rocks crop out (Fig. 2). The form ation consists of five main lithologic units, consisting, in ascending order, principally of silty shale, porcelaneous and cherty shale, phosphatic shale, diatom ite and radiolarian mudstone. Other kinds of rock are found in each unit; those mentioned are the prevailing ones. Perhaps each of these divisions deserves member rank, but in view of the absence of adequate exposures the three lower ones are grouped as the Altam ira shale member. The diatom ite constitutes the Valmonte diatom ite member; and the radiolarian mudstone is called the M alaga mudstone m em ber."All samples from the Palos Yerdes Hills containing radiolarians described in this paper came from the Valmonte diatomite member and the Malaga mudstone member. The Valmonte diatomite overlying the Altamira shale consists of dia tomite and diatomaceous silt or clay shale, estimated as 750 feet thick. Six samples came from this mem...

Antarctic Radiolaria from the Southeast Pacific Basin, Deep Sea Drilling Project, Leg 35

“…The Prunopyle titan reported from Antarctic sediments by numerous authors is not believed to be the same species that was originally described by Campbell and Clark (1944) from Miocene sediments in California. Campbell and Clark (1944) clearly state that P. titan does not have any internal medullary shell.…”

“…Campbell and Clark (1944) clearly state that P. titan does not have any internal medullary shell. The Antarctic form referred to as P. titan, on the other hand, does have a loosely packed internal structure composed of at least four spirals.…”

Radiolarians from the Kerguelen Plateau, Leg 119

“…foremanae, Lithomelissa sphaerocephalis, and Calocyclas asperum. P. polyacantha was described by Campbell and Clark (1944) from the Miocene deposits of southern California. Its representatives were also observed in upper Eocene/ Oligocene sediments of Leg 29 .…”

Taxonomy and species diversity of Holocene pylonioid radiolarians from surface sediments of the northeastern Indian Ocean

“…The type image of the representative species shows small pores on the 2nd and 3rd rings, which are different from those of specimens previously identified as this species (e.g., Sharma and Ram, 2003). Circodiscus microporus differs from Circodiscus circularis (Campbell and Clark, 1944) because the rings are apparently wider in the former than in the latter.…”