Gideon Tibor

Late Tertiary subsidence history of the southern Levant Margin, eastern Mediterranean Sea, and its implications to the understanding of the Messinian Event

The late Tertiary subsidence history of the southern Levant continental margin, situated in the southeastern Mediterranean Sea, was quantitatively analyzed. Paleodepth reconstruction across the margin off Ashdod suggests the existence of a deep basin in pre-Messinian time which resembles the present one. This implies that. the deposition of the evaporites in the study area during the Messinian desiccation of the Mediterranean Sea occurred in a deep basin. The path of the tectonic subsidence of the basement since early Tertiary is generally smooth as expected from the nature of the thermal subsidence. The unconformity beneath the Messinian indicates erosion of 50-200 m at the coastal plain. In the Pliocene, the tectonic subsidence in the coastal plain and shelf area diverts from the expected thermal path and increases from 250 m to 450 m, respectively. In the Quaternary the rate of tectonic subsidence nearly resumed the predicted thermal subsidence. Sedimentation and subsidence rates decrease but are still higher than those of the pre-Messinian. We suggest that the evolution of the southern Levant margin is most probably influenced by three main causes: (1) the Messinian event in late Miocene, (2) the deposition of large volumes of Nile derived sediments since the Pliocene, and (3) the flexural response of the lithosphere to the load from the Nile delta and/or from the uplift of the Judea Mountains (the western shoulder of the Dead Sea Transform). We interpret the latter to be the cause of the anomalous subsidence of the southern Levant margin during the Pliocene.

The northern edge of the Gulf of Elat

Abstract The Gulf of Elat (Aqaba) is located at the southern portion of the Dead Sea transform. Three large sedimentary basins exist within the gulf. The northern edge of the Gulf of Elat, the Gulfs Head, forms the divide between the northern sedimentary basin of the gulf, the Elat Deep basin, and the on-land sedimentary basins of the southern Arava Valley. At this location the Gulf of Elat narrows considerably. A transverse fault zone separates the Elat Deep basin from the Gulfs Head. This fault zone is highly deformed, and consists of numerous distinct faults and subbottom structures. Several structural elements within this zone extend westward into a graben on the Sinai Peninsula which is older than the Gulf of Elat. The transverse fault zone connects two large strike-slip faults segments of the Dead Sea transform. The southern segment borders the Elat Deep on the east, and the northern segment borders the Gulfs Head on the west. Some left-lateral displacement is also occurring along the transverse fault zone. The transverse fault zone is, thus, part of the main Dead Sea transform and not a secondary fault as is found at the southern end of the Elat Deep. It is associated with a magnetic anomaly which is one of the largest recorded in the Gulf of Elat. The existence of such an anomaly possibly indicates basaltic intrusion along this zone. Other instances where transverse faults extend away from the basinal areas, like at the northern boundary of the Elat Deep, can be recognized along the Dead Sea rift. These structures may suggest that the longitudinal dimension of several of the basins is determined during early stages of their formation.

Late Tertiary seismic facies and structures of the Levant passive margin off central Israel, eastern Mediterranean

Abstract The Late Tertiary seismic facies and structures of the Levant passive margin off central Israel in the eastern Mediterranean Sea were studied by the interpretation of more than 3000 km of seismic reflection profiles, most of them previously unpublished single-channel profiles. The Neogene growth and evolution of this margin was influenced by the interaction of three main processes: (1) the outbuilding and loading of the margin by the Nile sediments since the Pliocene, (2) uplift and tectonic subsidence related to the tectonic activity along the Dead Sea Transform, and (3) the effect of the above processes on the thick Messinian evaporites which caused many salt-tectonic features including flowage, piercement diapirs, slumps, and en-echelon listric normal faults in the supra-salt sediments. We suggest that the study area may be divided into two segments, north and south of Caesarea. These segments vary in their depositional environment, the amount of sediment supply and load, salt-related features and tectonic activity. We propose that the northern segment is affected by low sediment supply and by the continued uplift of the Carmel structure, and that this segment may even be a part of this structure. The southern segment has been affected by the deposition and loading in the Nile-derived sediments since the Pliocene. Three main depositional sequences were observed in the southern segment: (1) sequence I (Early Pliocene) onlaps the top of the Messinian evaporites representing a rise of sea-level and renewed subsidence, (2) sequence II (Early Pleistocene) is lens-shaped, thinning to the north, west and east and was derived during a relatively short time interval from the Pre-Nile, and (3) sequence III (since the Pleistocene) represents a major episode of continental shelf construction.

Synoptic Measurements of Chlorophyll-a and Suspended Particulate Matter in a Transitional Zone from Polluted to Clean Seawater Utilizing Airborne Remote Sensing and Ground Measurements, Haifa Bay (SE Mediterranean)

Abstract The hyperspectral Compact Airborne Spectrographic Imager (CASI) sensor was implemented to monitor water quality in a transitional zone from polluted to clean seawater, in Haifa Bay and adjacent river estuaries, at the northern part of the Mediterranean coast of Israel. Synoptic measurements of optical data acquired from the airborne scanner were used to map chlorophyll- a (chl- a ) and suspended particulate matter (SPM) concentrations in surface waters in the study area. This airborne hyperspectral scanner was found as an expedient monitoring tool for the relatively small geographic area of the current study, as it enabled to reveal the patchy distribution, and sharp concentration changes of the mapped water characteristics. The distribution of SPM concentrations in Haifa Bay was mainly dictated by the polluted riverine inputs, with concentrations between 1 and 3 mg l −1 at its seaward border and higher by more than 1 order of magnitude at the river estuaries. The chl- a concentrations mapped and measured in this survey were unusually low ( −1 ) due to a long-period intermission of anthropogenic phosphate and nitrate input to the bay. SPM and chl- a spatial distributions along the lower rivers system exhibit variations which could be plausibly explained by the hydrological structure and geochemical impacts on the riverine water sources. The correlation between SPM and some particulate heavy metal concentrations was found as a useful tool for monitoring such environmental hazardous substances.

A rapid and cost-effective method for vegetation mapping and nutrient content evaluation along the receding Lake Kinneret shoreline using oblique airborne video integrated into the GeoSky ™ system

Lake Kinneret is a major water source for the State of Israel, hence it is managed and preserved by the Israel Water Authority. Mapping the new vegetation growth along the exposed shores of Lake Kinneret during periods of retreating lake water levels is of great importance in the management of the lake and its water quality. When the lake level rises this vegetation is covered by water, decays, and releases nutrients into the lake, possibly enhancing algal blooms. In December, 2001, when the lake level was -214.72 m, a rapid and cost-effective vegetation mapping was done along the retreating shoreline using a GeoSky ™ system that integrates oblique airborne video synchronized with Differential Global Positioning System (DGPS) and an electronic compass, and displays them within a Geographic Information System (GIS). Six major vegetation classes with twelve subclasses were interpreted from the video along the newly exposed shoreline between -209 m (highest lake level) and -214.72 m, their borders mapped, an...

Structure and Tectonic Development of the Kinneret Basin

The Sea of Galilee is a freshwater lake in northern Israel, occupying a part of the Lake Kinneret basin along the Dead Sea fault. The basin is located in an area of tectonic complexity, where the main north–south trending segments of the Dead Sea fault intersect with a secondary system of northwest–southeast and east–west trending faults in the Galilee. Plio–Pleistocene basalt flows and intrusions varying in thickness are present around the lake. This tectonic setting produced the complicated sub-bottom structure of the basin. Numerous studies have dealt with this issue using various methods: seismic reflection and refraction, heat flow, bathymetry, magnetics, gravity, and seismicity. This chapter summarizes the findings of the previous and recent studies of the sub-bottom and floor of the lake. The Lake Kinneret basin is composed of two subbasins. The northern subbasin is the most tectonically active zone in the lake and forms the deepest bathymetric part of it. The southern subbasin is the deepest part of the basin, filled with 5–8 km of sediments. Both longitudinal boundary faults and transverse faults are present in the lake; however, their accurate geometry is in dispute. Structural evolution of the basin is associated with several tectonic processes. The interaction between the two fault systems may have caused rotational opening and transverse normal faulting that formed the northern subbasin. Strike–slip motion along the main segments of the Dead Sea fault is probably responsible for the pull-apart opening of the southern subbasin.

SISCAL project: establishing an internet-based delivery of near-real-time data products on coastal areas and lakes from satellite imagery

SISCAL (Satellite-based Information System on Coastal Areas and Lakes) is a pan-European project dedicated to develop facilities to provide end-users with customized and easy-to-use data for environmental monitoring of coastal areas and lakes. The main task will be to create a software system providing Near-Real-Time information on the aquatic environment (using instruments such as AVHRR, MODIS or MERIS) and ancillary GIS-data. These products will be tailored to individual customers needs, allowing them to exploit Earth Observation (EO) data without extensive in-house knowledge. This way, SISCAL aims at closing the gap between research institutes, satellite data providers and the actual end-users. Data and information exchange will entirely take place over the internet, from the acquisition of satellite data raw from the providers to the dissemination of finalized data products to the end-users. The focus of SISCAL is set on the optimal integration of existing techniques. The co-operation between the ten SISCAL partners, including four end-users representative of public authorities from local to national scale, aims at strengthening the operational use of EO data in the management of coastal areas and lakes.

Lake Bathymetry and Bottom Morphology

The bathymetry and morphology of Lake Kinneret is influenced by its complex tectonic structure and by high annual sedimentation (~ 100,000 t year−1 for the past 50 years). In general, the lake floor has an asymmetric shape with mild bathymetry at its western part and steep bathymetry at the eastern part. Based on a new multibeam bathymetric mapping conducted in 2008, the total surface area of the lake is 168.7 km2 (at water level − 209 m a.m.s.l.) with a maximum depth of 41.7 m (− 253.7 m). The water storage capacity ranges from 4,325 to 3,661 × 106 m3 at water levels of − 209 to − 214 m, respectively. A comparison of the 2008 multibeam bathymetry to echosounder bathymetry of 1986/1987 revealed dramatic changes in the lake bathymetry. The southern basin became significantly shallower; sediment accumulation over the 21 years between the two surveys may have accounted for up to 2 m rise in the lake floor at some places, estimated to represent ~ 10 × 106 t of sediment. The northern basin however does not show evidence for massive sedimentation (< 0.5 m), whereas judging by the − 214 m (a.m.s.l.) contour, the littoral perimeter had been eroded significantly. The existence of bathymetric lineaments on the lake floor indicates recent and active processes in the lake. Two main lineament trends were found: a N–S trend, mainly on the eastern and southwestern borders of the lake, probably associated with active traces of the Dead Sea fault system and a NW–SE trend, which is probably the continuation of the normal faults of the eastern Galilee fault system. The major morpholineament found in the 2008 bathymetry is located in the northwestern deeper parts of the lake (− 232 to − 242 m) and is N–S oriented. The epicenters of the October 2013 earthquakes are found in the vicinity of this lineament.