Late Miocene Mediterranean desiccation: topography and significance of the 'Salinity Crisis' erosion surface on-land in southeast Spain: Comment

One of the most striking aspects of the Mediterranean "Messinian Salinity Crisis" as observed in landbased sections, is the basin-wide synchronicity in facies change (Krijgsman et al., 1999a). The Messinian succession of the Caltanisetta Basin on Sicily serves as the classical standard for these facies changes, which can also be recognised elsewhere in the Mediterranean, i.e. on Cyprus, Crete, northern Italy and southern Spain. It starts with an alternation of open marine marls and sapropels, passes via diatomites into evaporitic limestones, gypsum and halite of the "Lower Evaporites" (of marine origin) and, following an erosional unconformity, ends with the "Upper Evaporites" and associated fresh to brackish water deposits of the Lago Mare that are essentially of non-marine origin and contain a caspi-brackish ostracode fauna. The erosional unconformity between the "Lower and Upper Evaporites" is assumed to reflect the phase of most extreme sea level drawdown in the Mediterranean that caused significant erosion and localised channel entrenchment on the continental shelves and slopes

Astrochronology for the Messinian Sorbas basin (SE Spain) and orbital (precessional) forcing for evaporite cyclicity

The Sorbas basin of SE Spain contains one of the most complete sedimentary successions of the Mediterranean reflecting the increasing salinity during the Messinian salinity crisis. A detailed cyclostratigraphic study of these successions allows a correlation of the sedimentary cycle patterns to astronomical target curves. Here, we present an astrochronological framework for the Messinian of the central part of the Sorbas basin. This framework will form a solid basis for high-resolution correlations to the marginal carbonate facies and to the Central Mediterranean area. The early Messinian Abad Member contains 55 precession induced sedimentary cycles marked by homogeneous marl-opalrich bed alternations in the `Lower Abad' and by homogeneous marl-sapropel alternations in the `Upper Abad'. Astronomical tuning results in an age of 5.96 Ma for the transition to the Yesares evaporites and thus for the onset of the `Messinian salinity crisis'. The marl±sapropel cycles of the `Upper Abad' are replaced by gypsum±sapropel cycles (14) in the Yesares Member, indicating that the evaporite cyclicity is related to precession controlled oscillations in (circum) Mediterranean climate as well. As a consequence, gypsum beds correspond to precession maxima (insolation minima) and relatively dry climate, sapropelitic marls to precession minima (insolation maxima) and relatively wet climate. An alternative (glacio-eustatic) obliquity control for evaporite cyclicity can be excluded because the number of sedimentary cycles with a reversed polarity is too high. Sedimentation during the Abad, Yesares, and the overlying coastal sequences of the Sorbas Member, took place in a continuously marine environment, indicating that marine conditions in the Sorbas basin prevailed at least until 5.60-5.54 Ma. According to our scenario, deposition of the Yesares and Sorbas Member took place synchronously with deposition of the `Lower Evaporites' in the Central Mediterranean. Finally, the continental Zorreras Member consists of 8 sedimentary cycles of alternating reddish silts (dry climate) and yellowish sands (wet climate) which correlates very well with the `Upper Evaporites' and Lago Mare facies of the Mediterranean

Quaternary Reef Record of Differential Uplift at Luwuk, Sulawesi East Arm, Indonesia.

The coastal morphology of Luwuk (Sulawesi) is dominated by raised coral reef terraces, reaching elevations of over 400 m. A lower group of 6 to 10 terraces reach maximum heights varying between 30 and 100 m. A middle group, elevated up to 250 m, forms an 18° to 22° seaward sloping surface that is bordered by coast-parallel faults. The upper group of terraces is more than 400 m above sea level. Four reef terraces at 410, 62, 19 and 6.6 m above high tide have U/Th ages ranging from 350 ka to 67 ka and, except for the oldest terrace, can be correlated with several stages of interglacial reef growth at Huon Peninsula, New Guinea. Using the sea level curve established for the Huon reefs, uplift rates for the Luwuk area can be calculated. The highest terrace has risen at an average rate of 184 cm·ka-1. The 3 dated terraces of the lower group also indicate net uplift, but at a much lower rate, which is partially due to subsidence at 53 cm·ka-1 between 101 ka and 67 ka. Intermittent subsidence could be due to isostatic compensation and/or drag by the downthrown parts during periods of crustal relaxation in the fault zone