Bulletin of the Geological Survey of Japan Vol.50 No.4 (1999)

Cover photograh | Table of Contents |

Cover photograh


Mesozoic Gorkhi Granite in Mongolia

This granite corps out about 50km east of Ulaanbaatar, capital of Mongolia. It is mainly composed of coarse-grained biotite granite, often showing porphyritic texture of K-feldspar phenocryst. It intruded in late Triassic to early Jurassic and its lead radiometric age of zircon is 215±7 Ma. Optical quartz was mined from pegmatite veins in this granite. This photograph was taken at the excursion of East Eurasian Geological Seminar in October, 1998 (see Takahashi's article in this volume). The rock is called“Turtle Rock”because of the shape.

(Photoed by Yuhei TAKAHASHI, Oct. 1998)

Table of Contents

Seismic profiling of deep geological structure in the Kobe and Ashiya areas Takanobu YOKOKURA, Kazuo Yamaguchi, Naomi KANO(, Teruki MIYAZAKI, Takeshi IKAWA, Yohichi OHTA, Taku KAWANAKA and Susumu ABE (245-267) 50-04_01.pdf(4,187KB)
Diatom biostratigraphy of the Middle Miocene Hatatate Formation, Sendai City, Miyagi Prefecture Yukio YANAGISAWA (269-277) 50-04_02.pdf(1,285KB)
[ Notes and Comments ]
Geological research works in Mongolia
Yuhei TAKAHASHI (279-289) 50-04_03.pdf(1,751KB)
Abstracts for Geological Survey Seminar, No. 258
Oman ophiolite and oceanic crust(291-303)