Calibrating the duration and timing of the Messinian salinity crisis in the Mediterranean: linked tectonoclimatic signals in thrust-top basins of Sicily
Calibrating the duration and timing of the Messinian salinity crisis in the Mediterranean: linked tectonoclimatic signals in thrust-top basins of Sicily
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DOI：
10.1144/gsjgs.156.4.0827
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发表时间：
1999-07-01
影响因子：
2.7
通讯作者：
Jones, RE
中科院分区：
文献类型：
--
作者：
Butler, RWH;McClelland, E;Jones, RE
影响地中海的墨西拿“盐度危机”是地质记录中已知的基准面波动最引人注目的例子之一：在一个持续时间不到2 Ma的阶段内，幅度可能为2 km。西西里中部的卡尔塔尼塞塔盆地内的沉积物被用来校准这些波动的持续时间和时间。被称为“第一旋回”和“第二旋回”的两个碎屑岩系列被区域间不整合面隔开。第一个旋回为区域海退，第二个旋回为海进。这些矿床的年代地层标定是通过一项相关的磁性地层学、构造学和沉积学研究提供的。退化是长期的。最早的辉长岩在6.88Ma前的C3 Ar时代早期富集，最年轻的辉长岩在6.0Ma后的C3 An时代晚期富集。在此期间，海岸线向盆地内移动了70 km，在垂直剖面上，海平面相对下降了0.3-0.4 m ka（-1）。最低峰可能发生在5.8- 5.5Ma。海侵，标志着积累的“第二个周期”的存款，这一切都记录反向磁化（C3 R），显然发生得更快（200万年），在返回到“正常”的海洋条件在地中海中部晚在Chron C3 R。在位于卡尔塔尼塞塔盆地下方的冲断带内，局部构造变形速率相对较慢。因此，西西里的墨西拿“盐度危机”的时间和速率可能普遍适用于该地区的其他盆地，并有助于支持新近纪这一部分的气候变化速率。
The Messinian 'salinity crisis' which affected the Mediterranean represents one of the most dramatic examples of base-level fluctuation known in the geological record: an amplitude of perhaps 2 km within a stage with a duration of less than 2 Ma. Deposits within the Caltanissetta Basin of central Sicily are used to calibrate the duration and timing of these fluctuations. Two successions of evaporites termed 'First Cycle' and 'Second Cycle', are separated by an inter-regional unconformity. The first cycle is regionally regressive while the second is transgressive. Chronostratigraphic calibration of these deposits has been provided by a linked magnetostratigraphic, structural and sedimentological study. The regression was protracted. The earliest evaporites in our study accumulated early in Chron C3Ar (pre 6.88 Ma) and the youngest accumulated late in chron C3An (post 6.0 Ma). During this interval the basinward shift in coastline was 70 km and in vertical section implies a relative fall in sea level at 0.3-0.4 m ka(-1). Lowstand probably finally occurred at 5.8-5.5 Ma. Transgression, marked by accumulation of the 'second cycle' deposits, which all record reversed magnetizations (C3r), apparently occurred far more rapidly (200 ka), prior to the return to 'normal' marine conditions in the central Mediterranean late in Chron C3r. Local rates of tectonic deformation are relatively slow within the thrust belt which underlies the Caltanissetta Basin. Therefore, it is likely that the timing and rates of the Messinian 'salinity crisis' on Sicily are generally applicable to other basins in the region and help to underpin rates of climate change within this part of the Neogene.