Uranium-series ages of fossil corals from Mallorca, Spain: The “Neotyrrhenian” high stand of the Mediterranean Sea revisited

The emergent marine deposits of the Mediterranean basin have been recognized as an important record of Quaternary sea level history for more than a century. Previous workers identified what have been interpreted to be two separate high stands of sea in the late Quaternary, namely the “Eutyrrhenian” (thought to be ~120 ka) and the “Neotyrrhenian” (thought to be either ~100 ka or ~80 ka). On Mallorca, Spain, both of these named deposits lie close to present sea level, implying paleo-sea levels slightly above present during both marine isotope stages (MIS) 5.5/5e and either 5.3/5c or 5.1/5a. If these interpretations are correct, they conflict, at least in part, with sea level records from far-field localities. Weanalyzed corals fromtheNeotyrrhenian beds onMallorca,which gave U-series ages from~126 ka to ~118 ka. These ages are consistent with previously published amino acid data that show that the Neotyrrhenian and Eutyrrhenian deposits are not significantly different in age. A fossil molluscan fauna from the Neotyrrhenian deposits onMallorca has a warm-water paleozoogeographic aspect, with nine southward-ranging species and four extralimital southern species. When compared with sea surface temperatures obtained from planktonic foraminifera and alkenones from ODP core 977 in the nearby Alboran Sea, the only time period that shows comparable warmth is MIS 5.5/5e, consistent with the U-series ages of corals from the Neotyrrhenian deposits. We propose that the Neotyrrhenian deposits are a beachrock facies of the same age as the Eutyrrhenian deposits. This interpretation is consistent with the differences in physical sedimentology of the two deposits, explains the U-series and amino acid data indicating the same age, is consistent with the very slight elevation difference of the Neotyrrhenian and Eutyrrhenian beds, and explains the similar, though not identical paleozoogeographic aspects of their fossil faunas

A Late Pleistocene Wetland Setting in the Arid Jurf ed Darawish Region in Central Jordan

Current conditions in the southern Levant are hyperarid, and local communities rely on fossil subsurface water resources. The timing of more favourable wetter periods and also their spatial characteristics are not yet well constrained. To improve our understanding of past climate and environmental conditions in the deserts of the southern Levant, sedimentary sections including artefact-bearing beds from Jurf ed Darawish on the Central Jordanian Plateau were investigated using sedimentological and micropalaeontological analyses and OSL dating. Grain-size analysis and structures of the clayey-silty sediments show that they mainly represent reworked loess deposits. The OSL ages suggest that these fine-grained sediments were accumulated during Marine Isotope Stages (MIS) 5-3. Recorded ostracod valves (mostly Potamocypris, Ilyocypris and Pseudocandona), remains of aquatic and terrestrial gastropod shells, and charophyte gyrogonites and stem encrustations indicate that an in-stream wetland existed at the location of Jurf ed Darawish during MIS 5-4 which was replaced by a vegetated alluvial plain in MIS 3. The prevailing aggradational setting was replaced by an erosional setting sometime after 30 ka. Abundant artefacts, distributed over a vertical range of up to 40 cm in a bed covered by a sedimentary sequence of 12-m thickness, provide evidence for the presence of humans in the region during a relatively long period from ca. 85 to 65 ka. The reconstruction of an in-stream wetland at Jurf ed Darawish, and the presence of humans at the site and in other desert regions of the Jordanian Plateau, the Wadi Arava/Araba, and the Negev and the Nefud deserts, show that the regional climate in the late MIS 5 and MIS 4 was significantly wetter than today and provided favourable conditions for humans in the Southern Levant and the northwestern Arabian Peninsula

Origin of the Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

The Sinai-Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative to K-feldspar and plagioclase. However, Sinai wadi sands have abundant calcite, whereas Nile Delta sands have little or no calcite. Overall, the mineralogical data suggest that the dunes are derived dominantly from the Nile Delta, with Sinai wadi sands being a minor contributor. Geochemical data that proxy for both the light mineral fraction (SiO2/10-Al2O3 + Na2O + K2O-CaO) and heavy mineral fraction (Fe2O3-MgO-TiO2) also indicate a dominant Nile Delta source for the dunes. Thus, we report here the first empirical evidence that the Sinai-Negev dunes are derived dominantly from the Nile Delta. Linkage of the Sinai-Negev erg to the Nile Delta as a source is consistent with the distribution of OSL ages of Negev dunes in recent studies. Stratigraphic studies show that during the Last Glacial period, when dune incursions in the Sinai-Negev erg began, what is now the Nile Delta area was characterized by a broad, sandy, minimally vegetated plain, with seasonally dry anastomosing channels. Such conditions were ideal for providing a ready source of sand for aeolian transport under what were probably much stronger glacial-age winds. With the post-glacial rise in sea level, the Nile River began to aggrade. Post-glacial sedimentation has been dominated by fine-grained silts and clays. Thus, sea level, along with favorable climatic conditions, emerges as a major influence on the timing of dune activity in the Sinai-Negev erg, through its control on the supply of sand from the Nile Delta. The mineralogy of the Sinai-Negev dunes is also consistent with a proposed hypothesis that these sediments are an important source of loess in Israel

Towards a map of the Upper Pleistocene loess of the Po Plain Loess Basin (Northern Italy)

Upper Pleistocene (MIS 4-2) loess sequences occur in most of continental Europe and in Northern Italy along the Po Plain Loess Basin. Loess is distributed along the flanks of the Po Plain and was deposited on glacial deposits, fluvial terraces, uplifted isolated hills, karst plateaus, slopes and basins of secondary valleys. Loess bodies are generally tiny and affected by pedogenesis, being locally slightly reworked by slope processes and bioturbation. Notwithstanding, loess in the Po Plain is an important archive of paleoenviron-mental record and its mapping provides new insights in paleoenvironmental and palaeoseismic reconstructions of Northern Ital

Dose recovery and residual dose of quartz ESR signals using modern sediments : Implications for single aliquot ESR dating

Electron spin resonance (ESR) dating is a promising method for dating sedimentary quartz beyond a million years. Here we investigate the use of modern quartz samples with well bleached optically stimulated luminescence (OSL) signals to study the bleachability of the ESR signals, and to further check the applicability of the ESR single aliquot regenerative dose (SAR) protocol. The residual doses from five samples using both the Al- and Ti-centres were in general found to be large and, especially for the Al-centre, with a large variability. Although it is known that the Ti-centre is fully bleachable in nature, a subtraction of the residual dose using a modern analogue should be considered. Dose recovery tests were performed by using the single aliquot regenerative and added dose (SARA) method, and the dose recovery ratio (measured-to-added dose ratio) was obtained from the slope of the added vs. measured dose plot. The dose recovery ratio from the Ti-centre was satisfactory for all five samples indicating the validity of the proposed ESR SAR protocol. However, only one sample yielded a SARA plot for the Al-centre. This could be explained by the decrease in sensitivity caused by the annealing step in the SAR protocol and/or to the erroneous subtraction of the intensity of the peroxy centre, which overlaps with the Al-centre

Large floods during late Oxygen Isotope Stage 3, southern Negev desert, Israel

Slackwater deposits were found in a cave in the Nahal Netafim catchment (35 km2), near the head of the Gulf of Aqaba in the southern Negev, Israel. The sedimentological record includes 27 large paleofloods, dated by infrared stimulated luminescence to 33,000-29,000 years ago. The scatter of the ages and their large uncertainties prevented an assessment of the exact duration of the record and the specific timing of each flood. Bayesian analysis was used to adjust the dense dating results so that the time interval between the first and last flood deposit preserved in the cave could be estimated. Minimum peak discharges were reconstructed based on the estimated elevation of the Late Pleistocene channel bed as indicated by fluvio-pedogenic layers found near the cave. The average frequency of these large floods (200-600 m3 s-1) for the period between 33,000 and 29,000 years ago is about 1 flood per 150 years, while for the mid-late Holocene it is only 1 large flood per 1000 years. Eight floods out of the 27 recorded deviate from the envelope curves of mid-late Holocene paleofloods and measured floods in the hyperarid Negev desert, indicating a different hydroloclimatological regime. The anomalous large floods are hypothesized to have resulted from an increase in regional rainfall intensity and/or duration, attributed to increased frequency of the Red Sea Trough low-pressure system that affects the region. Available records indicate that the northern Negev and areas farther north in Israel controlled by Mediterranean pressure systems were wetter 40-20 ka BP. At the same time, the southern Negev, probably in response to the Red Sea Trough system, also experienced short episodes of more and/or larger rainstorms. The timing of these episodes in both the northern and the southern Negev towards the Last Glacial Maximum points to a potential synchronous strengthening of both the Mediterranean and Red Sea systems, currently acting at different seasons. These episodes of increased storminess in the area were brief and were not able to alter the general hyperarid conditions in this area

The Nature of Unusual Luminescence in Natural Calcite CaCO 3

Abstract. The unusual luminescence of particular varieties of natural pink calcite (CaCO 3 ) samples was studied by laser-induced time-resolved luminescence spectroscopy at different temperatures. The luminescence is characterized by intense blue emission under short-wave UV lamp excitation with an extremely long decay time, accompanied by pink-orange luminescence under long wave UV excitation. Our investigation included optical absorption, natural thermostimulated luminescence (NTL) and Laser-Induced Breakdown Spectroscopy (LIBS) studies. Two luminescence centers were detected: a narrow violet band, with λ max =412 nm, ∆=45 nm, two decay components of τ 1 =5 ns and τ 2 =7.2 ms, accompanied by very long afterglow, and an orange emission band with λ max =595 nm, ∆=90 nm and τ=5 ns. Both luminescence centers are thermally unstable with the blue emission disappearing after heating at 500 C, and the orange emission disappearing after heating at different temperatures starting from 230 ˚C , although sometimes it is stable up to 500 C in different samples. Both centers have spectral-kinetic properties very unusual for mineral luminescence, which in combination with extremely low impurity concentrations, prevent their identification with specific impurity related emission. The most likely explanation of these observations may be the presence of radiation-2 induced luminescence centers. The long violet afterglow is evidently connected with trapped charge carrier liberation, with their subsequent migration through the valence band and ultimate recombination with a radiation-induced center responsible for the unusual violet luminescence