The petrological control on the lithosphere-asthenosphere boundary (LAB) beneath ocean basins

doi:10.1016/j.earscirev.2018.06.011

IOCAS-IR > 海洋地质与环境重点实验室

	The petrological control on the lithosphere-asthenosphere boundary (LAB) beneath ocean basins
	Niu, Yaoling 1,2,3,4; Green, David H.5
	2018-10-01
发表期刊	EARTH-SCIENCE REVIEWS
ISSN	0012-8252
卷号	185 页码:301-307
通讯作者	Niu, Yaoling(yaoling.niu@durham.ac.uk)
摘要	The plate tectonics theory established 50 years ago has formed a solid framework for understanding how the earth works on all scales. In this theory, movement of the tectonic plates relative to the subjacent asthenosphere is one of the fundamental tenets. However, the nature of the boundary between the lithosphere and asthenosphere (LAB) beneath ocean basins remains under debate. The current consensus is that the oceanic lithosphere thickens with age by accreting asthenosphere material from below, and reaches its full thickness (L) similar to 90 km at the age (t) similar to 70 Ma. This lithospheric thickening fits the relation L alpha t(1/2), consistent with conductive cooling to the seafloor. A puzzling observation is that although conductive cooling continues, the oceanic lithosphere ceases to grow any thicker than similar to 90 km when t > 70 Ma. Small scale convection close beneath the LAB has been generally invoked to explain this puzzle, but why such convection does not occur until L similar to 90 km at t > 70 Ma has been a matter of conjecture. In this paper, we summarize the results of many years of experimental petrology and petrological studies of oceanic basalts, which indicate consistently that the LAB is a petrological phase boundary marking the intersection of the geotherm with the solidus of amphibole (pargasite)bearing peridotite. That is, petrologically, the LAB is an isotherm of similar to 1100 degrees C with L alpha t(1/2) for t < 70 Ma and an isobar of similar to 3 GPa (similar to 90 km) fort > 70 Ma. This unifying concept explains why the LAB depth increases with age for t < 70 Ma and maintains constant (similar to 90 km) for t > 70 Ma. The LAB, that is intrinsically determined by petrological phase equilibria, does not require small-scale convection. However, because the mantle above the LAB is the conductive lithosphere (pargasite-bearing peridotite) and below the LAB is the viscosity -reduced convective asthenosphere (peridotite + incipient melt), the small-scale convection in the asthenosphere close beneath the LAB (similar to 90 km) under older (t > 70 Ma) seafloors becomes possible, whose convective heat supply balances the conductive heat loss, maintaining the constant heat flow, seafloor depth and lithosphere thickness.
关键词	Lithosphere-asthenosphere boundary LAB Petrological control Amphibole dehydration solidus Petrology-controlled sub-LAB convection Plate model
DOI	10.1016/j.earscirev.2018.06.011
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China (NSFC)[41130314] ; National Natural Science Foundation of China (NSFC)[41630968] ; Chinese Academy of Sciences Innovation grant[Y42217101L] ; Qingdao National Laboratory for Marine Science and Technology[2015ASKJ03] ; NSFC-Shandong Joint Fund for Marine Science Research Centers[U1606401] ; University of Tasmania (Earth Sciences discipline) ; Research School of Earth Sciences, Australian National University ; National Natural Science Foundation of China (NSFC)[41130314] ; National Natural Science Foundation of China (NSFC)[41630968] ; Chinese Academy of Sciences Innovation grant[Y42217101L] ; Qingdao National Laboratory for Marine Science and Technology[2015ASKJ03] ; NSFC-Shandong Joint Fund for Marine Science Research Centers[U1606401] ; University of Tasmania (Earth Sciences discipline) ; Research School of Earth Sciences, Australian National University
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:000448493500015
出版者	ELSEVIER SCIENCE BV
引用统计	被引频次：45[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/156574
专题	海洋地质与环境重点实验室
通讯作者	Niu, Yaoling
作者单位	1.China Univ Geosci, Beijing, Peoples R China 2.Univ Durham, Dept Earth Sci, Durham, England 3.Chinese Acad Sci, Inst Oceanol, Beijing, Peoples R China 4.Qingdao Natl Lab Marine Sci & Technol, Qingdao, Peoples R China 5.Univ Tasmania, Sch Earth Sci, Hobart, Tas, Australia
第一作者单位	中国科学院海洋研究所
通讯作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	Niu, Yaoling,Green, David H.. The petrological control on the lithosphere-asthenosphere boundary (LAB) beneath ocean basins[J]. EARTH-SCIENCE REVIEWS,2018,185:301-307.
APA	Niu, Yaoling,&Green, David H..(2018).The petrological control on the lithosphere-asthenosphere boundary (LAB) beneath ocean basins.EARTH-SCIENCE REVIEWS,185,301-307.
MLA	Niu, Yaoling,et al."The petrological control on the lithosphere-asthenosphere boundary (LAB) beneath ocean basins".EARTH-SCIENCE REVIEWS 185(2018):301-307.

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