摘要
本文首次提出中国北方大陆下存在一个地幔热柱的论证,并提出亚热柱(sub—plume)的新概念。热柱的中心与边缘部分的隙间熔浆分别为苦橄质玄武岩与碱性玄武岩。在渐新世到中新世约18.4 Ma内,北方大陆以3.26cm/a的速率向东南飘移了约600km,使日本海、渤海—华北平原等脱离热柱。导致晚第三纪日本海扩张的停止,渤海—华北平原等早第三纪火山喷发的突然中止。火山喷发期间,在热柱头部若干个亚热柱的形成,好似若干个“铆钉”穿入岩石圈,有效地阻止了岩石圈的飘移(这时的飘移速率只有0.05cm/a),我们把火山喷发称为固定岩石圈的“铆钉效应”。
A mantle plume beneath the north part of China continent has been demonstrated firstly and a new concept of sub-plume has been presented by this paper. A mantle plume has been thought to be generated at the depth of about 400km. where the mantle material rising from the deeper level underwent partial melting, a buoyancy resulted from reverse density drove the plume with its diameter of about 400 - 500 km rising up to the base of lithosphere. where the plume spread out to form a mushroom - shaped head with its long and short diameter of 1800 km and 1350 km, respectively. The central and side plume have their interstitial melt of picritic and alkali basalts, respectively. During an interval of about 18.4 Ma from Oligocene to Miocene the north part of China continent had been drifted about 600 km southeastwards with a drifting rate of 3.26 cm/a . by which the Japan Sea. the Bohai-North China Plain and others had been departed from the plume, resulting in the sudden stopping of the Japan Sea and the Bohar - North China Plain from sea-floor spreading and volcanic eruption, respectively. In Neogene - Quaternary Changbai shan was located above the central plume, resulting in some much more intensive, widespread and long duration volcanic eruptions relative to the other volcanic areas, and a unique acid volcanic eruption of Tianchi among the north part of China continent in later Quaternary. During the duration of eruption the formation of several sub-plumes at the head of the mantle plume, and a succesion of volcanic eruptions are naw considered as several 'rivets' penetrating into the overlying lithosphere to make resistance against the lithosphere drifting (with only drifting rate of 0.05 cm/a), and we refer to the volcanic eruption as 'rivet effect' for fixing lithosphere.
出处
《现代地质》
CAS
CSCD
1992年第3期267-274,共8页
Geoscience
基金
国家自然科学基金资助项目
关键词
大陆
地幔
热柱
岩石圈
中国
mantle plume and sub-plume, lithosphere motion and 'rivet effect
