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Late Cenozoic paleoenvironments in the Sea of Okhotsk area

鄂霍次克海地区晚新生代古环境

基本信息

批准号：
07041083
负责人：
OGASAWARA Kenshiro
金额：
$ 3.52万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

In order to reconstruct the late Cenozoic paleoenvironmental history in the Sea of Okhotsk area, such two sections in Sakhalin as the Makarov and Schmidt Peninsula investigated from paleontological and geological point of views. On the basis of detailed columnar sections (1 : 1000 scale), samples for bio-and chrono-stratigraphical analysis collected more than 500 localities in Makarov region in 1995 and in Schmidt Peninsula in 1996. Paleontological studies such as Diatom, benthic Foraminifera, Mollusca, Pollen, Dinoflagellate have done as coupled with sedimentological studies (facies's analysis, heavy minerals and geochemical analysis). As the result, the Oligocene to Pliocene lithostratigraphy and biostratigraphy of the studied areas were established. A big chronological gape was first recognized between the Chefov and Verkhne Due Formation in Makarov region on the basis of the Dinoflagellate and Pollen biostratigraphy. The Ar-Ar dating, 22-23 Ma of the basaltic rocks from the Chefov Formation may indicated the initial rifting stage of the Sea of Okhotsk. The beds corresponding to the first mid-Neogene climatical optimum were recognized in the Verkhne Due Formation in Makarov region and Pili Formation in the Shmidt Peninsula based on benthic fossils and pollens. The Denticulopsis hyalina Zone was recognized both from the Maruyama (Makarov region) and Pili (Schmidt Peninsula) Formations, respectively. Molluscs occurred from the Machigar Formation in Schmidt Peninsula were comparable with those of the Oligocene Asagai Fauna of Japan. Consequently, the Cenozoic paleoenvironmental history of the Sea of Okhotsk area was well understood in reference to that of the Japanese Islands and Northern Pacific.

为了恢复鄂霍次克海地区晚新生代的古环境史，对库页岛马卡罗夫和施密特半岛剖面进行了古生物学和地质学研究。根据详细的柱状剖面图（1：1000比例），1995年在马卡罗夫地区和1996年在施密特半岛收集了500多个地点的生物和年代地层分析样本。对硅藻、底栖有孔虫、软体动物、花粉、甲藻等古生物进行了研究，并结合沉积学（相分析、重矿物和地球化学分析）进行了研究。建立了研究区渐新统至上新世的岩石地层和生物地层。根据沟鞭藻和花粉生物地层学资料，首次在马卡罗夫地区的Chefov组和Verkhne Due组之间发现了一个巨大的年代学断层。切福夫组玄武岩的Ar-Ar年龄为22-23 Ma，表明鄂霍次克海处于初始裂陷阶段。根据底栖化石和花粉，在马卡罗夫地区的Verkhne Due地层和施密特半岛的皮利地层中识别出对应于第一个新近纪中期气候最佳状态的地层。Denticulopsis hyalina带分别来自Maruyama组（Makarov地区）和皮利组（施密特半岛）。产于施密特半岛的Machigar组的软体动物可与日本渐新世浅盖动物群相比较。因此，鄂霍次克海地区新生代的古环境史可以参照日本列岛和北方太平洋的古环境史来理解。