研究人員指出，在冰島之下,，地幔熱柱中熱地幔材料的躍動(dòng)性上涌導(dǎo)致了北大西洋海床的上升,。新成果發(fā)表在7月在線出版的《自然—地球科學(xué)》上。大約5600萬年前,，海底平面被臨時(shí)性抬舉,，并在沉入海底之前因河水的沖蝕形成了海峽。
Ross Hartley和同事合作,，利用地震數(shù)據(jù)成像了蘇格蘭東部的奧克尼-塞得蘭群島西部的古代地貌,，今天，這一地帶被埋藏在2公里厚的沉積巖之下,。對這一地帶的地形剖面模型和重建地貌中河流的分析顯示,，海底亞表面是在一系列的離散步驟中被抬高的，這可能是因地幔熱柱中地幔材料溫度的間隙性升高所造成,。
在本期一篇相關(guān)的新聞和評述文章中,， Philip Allen指出：“Hartley等展示了冰島地幔熱柱中熱地幔材料脈動(dòng)的向上和側(cè)面的分布，與北大西洋海底上升模式之間的神奇關(guān)系,。”(生物谷 Bioon.com)
doi:10.1038/ngeo1191
PMC:
PMID:1
Transient convective uplift of an ancient buried landscape
Ross A. Hartley; Gareth G. Roberts; Nicky White; Chris Richardson
Sedimentary basins in the North Atlantic Ocean preserve a record of intermittent uplift during Cenozoic times1. These variations in elevation are thought to result from temperature changes within the underlying Icelandic mantle plume2. When parts of the European continental shelf were episodically lifted above sea level, new landscapes were carved by erosion, but these landscapes then subsided and were buried beneath marine sediments3. Here, we use three-dimensional seismic data to reconstruct one of these ancient landscapes that formed off the northwest coast of Europe during the Palaeocene–Eocene Thermal Maximum. We identify a drainage network within the landscape and, by modelling the profiles of individual rivers within this network, we reconstruct the history of surface uplift. We show that the landscape was lifted above sea level in a series of three discrete steps of 200–400 m each. After about 1 million years of subaerial exposure, this landscape was reburied. We use the magnitude and duration of uplift to constrain the temperature and velocity of a mantle-plume anomaly that drove landscape formation. We conclude that pulses of hot, chemically depleted, mantle material spread out radially beneath the lithospheric plate at velocities of ~35 cm yr−1.
