K. Bernhard Spörli

Triassic radiolarians from the ocean‐floor sequence of the Waipapa Terrane at Arrow Rocks, Northland, New Zealand

Abstract Triassic radiolarians are reported from two horizons in Waipapa Terrane at Arrow Rocks, Whangaroa area, Northland. This relatively undisturbed succession represents an ocean‐floor sequence, consisting (in ascending order) of basalt with limestone layers, bedded chert, black shale, and red, maroon and green siliceous mudstone. The age of the lower part of the section is Middle‐Late Permian. The radiolarian assemblages reported here indicate Early or Middle Triassic and Middle Triassic (Anisian) ages for maroon siliceous mudstones in the upper part of the section. Between strata of known Permian and Triassic age there is a thin potential Permian/Triassic boundary interval consisting of alternating black shale and grey chert. Radiolarian paleogeography indicates that the Arrow Rocks sequence experienced long distance plate tectonic displacement from a position of relatively low latitude in the Middle Permian and to a high latitude in mid‐Triassic time.

Mesozoic phosphatic and calcareous nodules containing well-preserved radiolarian fauna from the North Island, New Zealand

ニュージーランドには日本とよく似たチャート・砕屑岩を含む中・古生代の地質体が広く分布するが, 放散虫化石による生層序学的研究はようやく端緒に着いたばかりある. 我々は1995, 96年の2年にわたり, 国際学術研究 (代表: 酒井豊三郎)による, ニュージーランドの中生界を中心とした含放散虫岩の調査を行った. その結果のうち, ワイパパ, ムリヒク両テレーンの, 中生代南半球の極めて保存のよい放散虫化ヨを産するノジュールの産状を紹介する.