Middle Jurassic to Lower Cretaceous Radiolarian Biostratigraphy of Shikoku with Reference to Selected Sections in Lombardy Basin and Sicily

The biostratigraphic distribution of Middle Jurassic to Early Cretaceous radiolarians from nine sections in Shikoku, Japan is investigated with reference to four sections in the Lombardy Basin and Sicily. Documentation of the stratigraphic ranges of diagnostic radiolarian species permits the recognition of datum levels as the first order criteria for correlation. Thirteen radiolarian zones are proposed on the basis of 12 datum levels for a Middle Jurassic to Lower Cretaceous interval. These zones are, in ascending order : the Eucyrtidiellum unumaense Zone, Obesacapsula magniglobosa Interval-zone, Tricolocapsa tetragona Interval-zone, Guexella nudata Interval-zone, Archaeodictyomitra(?) mirabilis Interval-zone, Amphipyndax tsunoensis Interval-zone, Stylocapsa(?) spiralis Interval-zone, Gongylothorax sakawaensis Zone, Foremanella hipposidericus Zone, Zhamoidellum mikamense Zone (Podocapsa amphitreptera Interval-zone applied in Tethyan region), Sethocapsa cetia Interval-zone, Ditrabs sansalvadorensis Interval-zone and Sphaerostylus septemporatus Zone. A direct correlation of the Shikoku sequences with the Tethyan sequences is attempted mainly by means of these datum levels and zonation herein proposed. In addition, correlation of the proposed zones with those of previous authors is discussed. A detailed comparison of the proposed zonation with nannofossil data from both the Shikoku and Tethyan sections provides important clues to the age assignment of the radiolarian zones. A total of 152 radiolarian species are discriminated by using both a transmitted light and scanning electron microscopy in this study, and 17 of them are described as new species

Tectonic significance of Late Cretaceous Radiolaria from the obducted Matakaoa Volcanics, East Cape, North Island, New Zealand(MEMORIAL VOLUME TO THE LATE PROFESSOR TERUHIKO SAMESHIMA)

Radiolarian faunas from several localities in the Matakaoa Volcanics of the Mangaroa Range, North Island, New Zealand indicate Late Cretaceous (Campanian to Maastrichtian) ages. This contrasts with Late Paleocene/Early Eocene ages obtained from foraminifera approximately 3 km higher in the section. The radiolarian faunas are cosmopolitan and may have been deposited at mid to high latitude. A new structural analysis indicates that the fossils occur in a sequence of intercalated pillow lavas, sediments and dolerites about 10 km thick equivalent of layer 2B of the oceanic crust. This great thickness implies that there has been much repetition by shortening deformation. Layering dips steeply; younging is generally to the north and the sequence is affected by km-scale steeply plunging folds associated with decollements. Structural development involved first formation of melange, and subsequent refolding of these structures to give the present dextral, steeply plunging folds. It is not clear yet how another phase of deformation, steepening and overturning of layering in the Matakaoa Volcanics, relates to these two tectonic events.publishe