AN IMPORTANT CURRENT REVERSAL (INFLUX) IN THE RIFIAN CORRIDOR (MOROCCO) AT THE TORTONIAN-MESSINIAN BOUNDARY: THE END OF TETHYS OCEAN
AN IMPORTANT CURRENT REVERSAL (INFLUX) IN THE RIFIAN CORRIDOR (MOROCCO) AT THE TORTONIAN-MESSINIAN BOUNDARY: THE END OF TETHYS OCEAN
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DOI：
10.1029/90pa00756
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发表时间：
1991-02-01
期刊：
影响因子：
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通讯作者：
Bonaduce, Gioacchino
中科院分区：
文献类型：
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作者：
Benson, Richard H.;Bied, Kruna Rakic-El;Bonaduce, Gioacchino
在摩洛哥的下墨西拿泥灰岩中发现的大西洋冷圈和温带中层动物群表明，在盐度危机之前，里菲安走廊存在一个强大的向东流动的底流。这种流入开始前沉积在古地中海，继续在珊瑚礁形成的物种多样性减少，并减少与“盐水”浓度的深水阶段的危机的初始阶段。在拉巴特附近的布雷格河谷的泥灰岩浓缩段中，最容易研究这种流入。这一“虹吸事件”的开始与Tortonian/Messinian边界（6.4 Ma，subchron 6 N1）相吻合。其特征是：（1）浮游有孔虫从暖热带上层Globorotalia menardii和Globigerinoides占优势的暖热带上层有孔虫转变为中层Gl。miotumida丛与conomiozea;（2）上冷层介形类动物群的突然出现，包括上冷层介形类动物群的出现，（3）超微植物群的变化，（4）6.3Ma全球碳转移的开始。虹吸的最初强流入阶段持续了至少0.7百万年，在Chron 5的中间之后减少，约。第575章失去了5.3 MA.当大陆性气候造成古地中海水收支赤字时，虹吸形成的条件。当贝蒂奇-里夫造山带前渊的构造运动改变了两个海峡的门槛时，发生了逆转，即里夫走廊和伊比利亚门户。在南部走廊，流入量迅速增加，从上升的大西洋密度跃层下方引入沃茨，而古地中海溢流水（PMOW）则继续流出北方伊比利亚门户。“推覆体”或滑枕岩的侵入，首先进入入口，然后进入走廊，导致PMOW流出的结束，终止了对虹吸管的需要，然后导致古地中海的孤立。
Atlantic psychrospheric and temperate mesopelagic faunas found in the lower Messinian marls in Morocco indicate that a strong, eastward flowing, bottom current was present in the Rifian Corridor before the Salinity Crisis. This influx began just before diatomite deposition in the Paleo-Mediterranean, continued during a decrease in species diversity in coral reef formation, and diminished with the initial stages of "brine" concentration in the deep-water phase of the Crisis. The influx is most readily studied in a condensed section of marl in the Bou Regreg valley near Rabat. The beginning of this "siphon event" coincides with the Tortonian/Messinian boundary (6.4 Ma, subchron 6N1). It is identified by (1) a change in the planktonic foraminifera from dominance of warm, tropical, epipelagic Globorotalia menardii with Globigerinoides to the temperate, mesopelagic Gl. miotumida plexus with conomiozea; (2) the sudden appearance of an upper psychrospheric ostracode fauna with Agrenocythere pliocenica and Oblitacythereis ruggierii, (3) a change in nannoflora; and (4) beginning of the 6.3 Ma Global Carbon Shift. The initial strong influx stage of the siphon lasted at least 0.7 m.y., decreasing after the middle of Chron 5, ca. 5.7, to be lost ca. 5.3 Ma. Conditions for the siphon formed when the continental climate created a deficit in the water budget of the Paleo-Mediterranean Sea. The reversal took place when tectonic movement in the foredeeps of the Betic- Rif Orogene changed the thresholds of the twin straits, the Rifian Corridor and the Iberian Portal. Inflow increased rapidly in the southern Corridor to draw in waters from beneath the rising Atlantic pycnocline, while Paleo-Mediterranean Overflow Water (PMOW) continued out of the northern Iberian Portal. The invasion of "nappes" or olistoliths, first into the portal and then into the corridor, led to the end of the outflow of the PMOW terminating the need for the siphon, and then to the isolation of the Paleo-Mediterranean.