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Mitzpe Ramon, Israel

Korngreen D.,Geological Survey of Israel | Benjamini C.,Ben - Gurion University of the Negev | Benjamini C.,Ramon Science Center
Sedimentary Geology | Year: 2011

A transect of the Middle to Late Triassic from the epicontinental belt to the shelf edge of the north Arabian margin is presented, based on new data from two boreholes in northern Israel. Two sedimentary systems are encountered along this traverse: the inland Meged-2 borehole represents the seaward extension of the epicontinental belt, with shallow- to deep-water carbonates, salina evaporites, and basinal shales, while Ga'ash-2, on the Levant margin, was positioned on an isolated platform separating the internal shelf-basin system from the open Tethys, displaying a shallower range of facies that is free of evaporites.Proximal-distal facies shifts are bundled into five low-order (LO) T-R cycles, ranging from Anisian (Pelsonian) to Norian, each composed of numerous high-order (HO) shallowing-upwards cycles. Meged-2 paleoenvironments imply an interior basin trapping sediments of the epicontinental belt, with numerous HO facies shifts indicating pulses of subsidence. Ga'ash-2 contains Lofer-like peritidal cycles and a late Anisian - early Carnian hiatus in place of the second LO cycle. The two orders of cycling are controlled by extrabasinal regional or eustatic change, and synsedimentary vertical movements.The divergent sedimentary patterns of the late Anisian-late Carnian can be attributed to NW-SE trans-tensile movements impacting on earlier Neotethyan extensional trends. Synsedimentary movements, represented locally by uplift at Ga'ash-2 and subsidence at Meged-2, controlled the influx of sea water into the epicontinental zone, and consequently, controlled the alternation of evaporite vs. carbonate systems. In the latest Carnian-early Norian, these facies belts become locked together forming a shallow, high energy shelf. This change reflects broad uplift and shifting of the locus of active differential movement into the Levant Basin. © 2010 Elsevier B.V. Source

Korngreen D.,Geological Survey of Israel | Benjamini C.,Ben - Gurion University of the Negev | Benjamini C.,Ramon Science Center
Sedimentary Geology | Year: 2010

The Triassic sedimentary pattern of the north Arabian margin represents a transition from continental to deep-marine; we here present a transect part of this suite from southern to northern Israel. Cuttings from the Ramalla (S) and Devora (N) boreholes were studied by petrographic and cathodoluminescence microscopy. Biotic and sedimentological components were grouped into microfacies, upon which a carbonate-evaporitic depositional facies model was based. Mid-to-inner ramp conditions persisted along the transect, essentially following a S-N depositional strike, with outer-ramp to basinal facies to the west. Five low-order (LO) cycles were identified and integrated into a sequence-stratigraphic model with eustatic, tectonic, and differential subsidence components: LO cycle 1 is Late Anisian (Pelsonian), cycle 2 is Late Anisian to Longobardian, cycle 3 is Early Carnian, cycle 4 is Late Carnian, and cycle 5 is at the Carnian/Norian transition. Facies range from supratidal via lagoonal facies in late HST or LST, to calcarenitic shoals and short-term deepening to offshore at maximum flooding. Cycles 1 and 2 are non-evaporitic, with a clastic influx event in cycle 2. Cycles 3 and 4 contain sabkha or salina evaporites in the lagoonal facies that end in the lower part of cycle 5. These facies group into a higher-order cyclicity with discrete events that can be correlated between the boreholes.Depositional and burial history were correlated to Alpine and Arabian Plate stratigraphy over 20. Myr, from the Anisian (Pelsonian) to the Norian. Siliciclastic, carbonate and evaporite-dominated environments indicate climates ranging from relatively humid to extremely arid. Rapid subsidence in the Late Anisian is attributed to Neotethyan rifting of northeastern Gondwana. From latest Anisian to Early Carnian, reduced subsidence took place in the face of eustatic sea level rise. Renewed subsidence in the Carnian is attributed to further Neotethyan rifting. Subsidence terminated in the Norian with uplift to the north, attributed to pre-volcanic doming. © 2010 Elsevier B.V. Source

Flako-Zaritsky S.,Ben - Gurion University of the Negev | Flako-Zaritsky S.,Geological Survey of Israel | Almogi-Labin A.,Geological Survey of Israel | Schilman B.,Geological Survey of Israel | And 3 more authors.
Marine Micropaleontology | Year: 2011

Enot Timsah is a spring-fed wetland ecosystem at the foot of the Carmel Mountain, a relict of the much larger Holocene Kabara swamps, at the northern outlet of the Yarqon-Tanninim mountain aquifer. This groundwater-surface water interaction zone supports a unique living foraminiferal and ostracod fauna. Sampling of water and sediment was carried out approximately monthly in 2002/3 as part of a study of the species richness and history of this distinctive ecosystem. Enot Timsah is nearly isothermal (23.98±0.4°C) and oligohaline with total dissolved solids (TDS) of 3,213±118.5mg/l. The water column is transparent and highly oligotrophic, with very low phosphate concentration. Living ostracods and Rose Bengal stained benthic foraminifera occur in low numbers. A monospecific population of the ostracod Cyprideis torosa lives at the surface, with a reproductive peak in April, 2002. Foraminifera occur throughout the topmost 0-4cm. Extreme oligotrophy of this ecosystem means that there is a low flux of phytoplankton, limiting abundance of surface-dwelling ostracods and foraminifera. Microbial decomposition of vascular plant debris was the food source for infaunal foraminifera. The low salinity means that living conditions are marginal explaining low numerical abundance of foraminifera. However, foraminiferal diversity is exceptionally high at Enot Timsah compared with other oligohaline environments, with 15 living benthic taxa and three additional species found in the dead assemblage. The living assemblage is composed of cosmopolitan agglutinants known to live in brackish environments, together with some calcareous hyaline and miliolid taxa. The exceptional foraminiferal diversity is attributed to four factors: the very stable conditions of salinity and temperature; the high Ca2+ and HCO3- concentrations derived from the karstic aquifer (promoting mineralization of calcareous tests), the maturity of the Kabara ecosystem dating from the early Holocene; and the repetitive reintroduction of cosmopolitan brackish foraminifera by avian transport. Increased numbers of living foraminifera with abnormal morphologies testify to stress conditions. Dead foraminifera are more abundant than living ones, with agglutinated foraminifera dominating the living assemblage, and calcareous forms dominating the dead assemblage. This taphonomic reversal is attributed to microbial decomposition of organic cement of the agglutinants, while the calcareous forms are resistant to dissolution because of the high Ca2+ and HCO3- of the aquifer-derived spring waters. The Holocene fossil record of the predecessors of the Kabara swamps therefore represents an estimated 10-40% of the information found in the living foraminiferal assemblage at Timsah. © 2011 Elsevier B.V. Source

Abramovich S.,Ben - Gurion University of the Negev | Yovel-Corem S.,Ben - Gurion University of the Negev | Almogi-Labin A.,Geological Survey of Israel | Benjamini C.,Ben - Gurion University of the Negev | Benjamini C.,Ramon Science Center
Paleoceanography | Year: 2010

The lengthy warm, stable climate of the Cretaceous terminated in the Campanian with a cooling trend, interrupted in the early and latest Maastrichtian by two events of global warming, at ~70-68 Ma and at 65.78- 65.57 Ma. These climatic oscillations had a profound effect on pelagic ecosystems, especially on planktic foraminiferal populations. Here we compare biotic responses in the tropical-subtropical (Tethyan) open ocean and mesotrophic (Zin Valley, Israel) and oligotrophic (Tunisia) slopes, which correlate directly with global warming and cooling. The two warming events coincide with blooms of Guembelitria, an extreme opportunist genus best known as the main survivor of the Cretaceous-Paleogene (K-Pg) catastrophe. In the Maastrichtian, Guembelitria bloomed in the uppermost surface water above shelf and slope environments but failed to reach the open ocean as it did at K-Pg. The coldest interval of the late Maastrichtian (~68-65.78 Ma) is marked by an acme of the otherwise rare species Gansserina gansseri, a deep-dwelling keeled globotruncanid. The G. gansseri acme event can be traced from the deep ocean even onto the Tethyan slope, marking copious production and circulation of cold intermediate water. This acme is abruptly terminated by extinction of the species, a dramatic reversal attributed to a short-term global warming episode. This extinction corresponds precisely with the second bloom of Guembelitria that began ~300 kyr prior to the K-Pg event. The antithetical relationship between blooming of Guembelitria and the G. gansseri acme reflects planktic foraminiferal sensitivity to warm-cool-warm-cool climatic oscillations marking the end of the Cretaceous. © Copyright 2010 by the American Geophysical Union. Source

Ashckenazi-Polivoda S.,Ben - Gurion University of the Negev | Ashckenazi-Polivoda S.,Geological Survey of Israel | Edelman-Furstenberg Y.,Geological Survey of Israel | Almogi-Labin A.,Geological Survey of Israel | And 2 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2010

The Upper Campanian Mishash Formation of southern Israel was deposited within the southern Tethys upwelling belt, with sea floors beneath this system characterized by poorly ventilated sediments approaching anoxia. This study was aimed at tracking the oxygen-poor gradient using benthic foraminiferal assemblages of organic-rich carbonates that are devoid of benthic macro-invertebrates and trace fossils. Quantitative data were gathered on foraminiferal faunas from four sections, namely Zin/Saraf, Qazra (Ashosh, Omer) and Qilt, from three basins affected by upwelling. Four distinct benthic foraminiferal assemblages characterize the organic-rich carbonate facies (B-assemblages A-D). These assemblages are distinguished by their species richness and composition, relative abundance, and dominance patterns. The low-diversity buliminid-dominated faunas correlate with high (up to 25 wt.%) total organic carbon levels, and inferred pore water oxygen levels range from nearly anaerobic to dysaerobic (up to 0.1 ml O2/l). The Zin and Qazra/Ashosh basins in southern Israel have representation of assemblages A and B, indicative of the most oxygen-depleted environments. Assemblages C and D are more common in better ventilated environments, such as the Qazra/Omer basin of southern Israel and the Qilt basin to the northeast. Nonetheless, all these basins have benthic assemblages indicative of low-oxygen pore waters (< 0.1 ml O2/l) beneath the upwelling belt, in comparison with the open Tethyan system indicated by the Shefela basin of central Israel. © 2010 Elsevier B.V. All rights reserved. Source

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