DOI: 10.1016/j.earscirev.2019.103061
论文题名: The Zanclean megaflood of the Mediterranean – Searching for independent evidence
作者: Garcia-Castellanos D. ; Micallef A. ; Estrada F. ; Camerlenghi A. ; Ercilla G. ; Periáñez R. ; Abril J.M.
刊名: Earth Science Reviews
ISSN: 00128252
出版年: 2020
卷: 201 语种: 英语
英文关键词: bedrock
; discharge
; evaporation
; flood
; flooding
; hydrodynamics
; Messinian
; sediment
; Algerian Basin
; Atlantic Ocean
; Gulf of Cadiz
; Mediterranean Sea
; Strait of Gibraltar
; Zanclea
英文摘要: About six million years ago, the Mediterranean Sea underwent a period of isolation from the ocean and widespread salt deposition known as the Messinian Salinity Crisis (MSC), allegedly leading to a kilometer-scale level drawdown by evaporation. One of the competing scenarios proposed for the termination of this environmental crisis 5.3 million years ago consists of a megaflooding event refilling the Mediterranean Sea through the Strait of Gibraltar: the Zanclean flood. The main evidence supporting this hypothesis is a nearly 390 km long and several hundred meters deep erosion channel extending from the Gulf of Cádiz (Atlantic Ocean) to the Algerian Basin (Western Mediterranean), implying the excavation of ca. 1000 km3 of Miocene sediment and bedrock. Based on the understanding obtained from Pleistocene onshore megaflooding events and using ad-hoc hydrodynamic modeling, here we explore two predictions of the Zanclean outburst flood hypothesis: 1) The formation of similar erosion features at sills communicating sub-basins within the Mediterranean Sea, specifically at the Sicily Sill; and 2) the accumulation of the eroded materials as megaflood deposits in areas of low flow energy. Recent data show a 6-km-wide amphitheater-shaped canyon preserved at the Malta Escarpment that may represent the erosional expression of the Zanclean flood after filling the western Mediterranean and spilling into the Eastern Basin. Next to that canyon, a ~1600 km3 accumulation of chaotic, seismically transparent sediment has been found in the Ionian Sea, compatible in age and facies with megaflood deposits. Another candidate megaflood deposit has been identified in the Alborán Sea in the form of elongated sedimentary bodies that parallel the flooding channel and are seismically characterized by chaotic and discontinuous stratified reflections, that we interpret as equivalent to gravel and boulder megabars described in terrestrial megaflood settings. Numerical model predictions show that sand deposits found at the Miocene/Pliocene (M/P) boundary in ODP sites 974 and 975 (South Balearic and Tyrrhenian seas) are consistent with suspension transport from the Strait of Gibraltar during a flooding event at a peak water discharge of ~108 m3 s−1. © 2019 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/166085
Appears in Collections: 气候变化与战略
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作者单位: Instituto de Ciencias de la Tierra Jaume Almera, ICTJA-CSIC, Barcelona, Spain; Marine Geology and Seafloor Surveying, Department of Geosciences, University of Malta, Msida, MSD 2080, Malta; Helmholtz Centre for Ocean Research, GEOMAR, Kiel, Germany; Instituto de Ciencias del Mar, ICM-CSIC, Barcelona, Spain; Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy; University of Sevilla, Spain
Recommended Citation:
Garcia-Castellanos D.,Micallef A.,Estrada F.,et al. The Zanclean megaflood of the Mediterranean – Searching for independent evidence[J]. Earth Science Reviews,2020-01-01,201