Tectonic control for evaporite formation in the Eastern Betics (Tortonian; Spain)

Abstract

Tectonic uplift and sea level lowering are two proposed mechanisms to explain the development of thresholds in front of the widespread evaporite basins of the circum-Mediterrranean region during the Miocene. Here we apply a multi-disciplinary approach to the continuously marine sequences of the Murcia-Cartagena basin to investigate which mechanism is responsible for the Tortonian evaporites of the Eastern Betics. First we develop a high-resolution chronology for the Venta de la Virgen section by integration of biostratigraphic, magnetostratigraphic and isotopic dating results. Next we construct palaeobathymetry and geohistory curves for this section and the Abad composite of the Sorbas basin. We show that the apparent differential vertical motions between the two sections cannot be explained by sea-level change but only by local tectonics. The Murcia-Cartagena basin shows significant tectonic uplift during the late Tortonian and early Messinian, while the neighboring Fortuna basin was rapidly subsiding. We conclude that tectonic activity on the Alhama de Murcia Fault was responsible for the emergence of a threshold that finally led to evaporite formation in the Fortuna basin.

Synchronous onset of the Messinian evaporite precipitation: First Mediterranean offshore evidence

“…The LO of G.nicolae has been dated at 6.8 Ma, marking the Lower/Upper Abad boundary in the Sorbas basin . In the same interval we found the FO of Rectouvigerina cylindrica, a benthic taxon that also appears around 6.8 Ma (Krijgsman et al, 2006;Sierro et al, 2001). Above the FO of R.cylindrica, we identified a change in the benthic foraminiferal assemblage.…”

“…5). The absence of coarse-grained detrital material indicates that the southwestern BP margin, although part of the Betic system, was not strongly affected by late Tortonian uplift (Krijgsman et al, 2006;Soria et al, 2001). Unlike the Eastern Betics, there is no biological or lithological evidence suggesting that the Tortonian Salinity Crisis (7.8-7.6 Ma; Krijgsman et al, 2000) influenced this area.…”

Origin and consequences of western Mediterranean subduction, rollback, and slab segmentation

“…After 8 Ma, the Alboran domain, including its overlying Middle Miocene and older extensional detachments and basins, has been shortened as a result of ongoing Africa‐Iberia convergence in a N‐S to NW‐SE direction, with deformation concentrated along sinistral N‐NE trending faults, dextral W‐NW trending faults, and reverse WSW‐W trending faults [ Aldaya et al ., ; Crespo‐Blanc et al ., ; Lonergan et al ., ; Lonergan and Platt , ; Martinez‐Martinez et al ., ; Booth‐Rea et al ., ; Platt et al ., ; Meijninger and Vissers , ; Marin‐Lechado et al ., ; Benmakhlouf et al ., ; Martinez‐Garcia et al ., ]. After 8 Ma, the region uplifted [ Krijgsman et al ., ; van der Laan et al ., ; Hüsing et al ., ], with as most spectacular effect the eventual disconnection of the waters of the Mediterranean basin from the Atlantic Ocean during the Messinian salinity crisis [ Krijgsman et al ., ].…”

Precessional variability of87Sr/86Sr in the late Miocene Sorbas Basin: An interdisciplinary study of drivers of interbasin exchange

“…The Messinian Salinity Crisis (MSC) caused ~6% of global ocean salt to be sequestered on the floor of the Mediterranean Sea [ McKenzie , ] in an evaporite layer ~1.5 km thick [ Hsü et al , ]. This extreme event was caused by restriction of the Miocene Atlantic‐Mediterranean connections (Figure ) as a result of tectonic uplift ranging from northern Morocco to Spain [ Krijgsman et al , , ] and eustatic sea level fall [ Manzi et al , ]. Much of our understanding of the conditions leading to the MSC and its timing is derived from astronomically tuned sequences exposed on the margins of the Mediterranean [e.g., Krijgsman et al , ; Manzi et al , ].…”