Papers by Omri Gadol
Journal of Marine Science and Engineering
Seafloor geoacoustic properties are important in determining sound propagation in the marine envi... more Seafloor geoacoustic properties are important in determining sound propagation in the marine environment, which broadly affects sub-sea activities. However, geoacoustic investigation of the deep seafloor, which is required by the recent expansion of deep-water operations, is challenging. This paper presents a methodology for estimating the seafloor sound speed, c0, and a sub-bottom velocity gradient, K, in a relatively deep-water-compacting (~1000 m) passive-margin setting, based on standard commercial 2D seismic data. Here we study the seafloor of the southeastern Mediterranean margin based on data from three commercial seismic profiles, which were acquired using a 7.2 km-long horizontal receiver array. The estimation applies a geoacoustic inversion of the wide-angle reflections and the travel times of the head waves of bending rays. Under the assumption of a constant positive K, the geoacoustic inversion converges to a unique set of parameters that best satisfy the data. The analy...
<p>Nile derived siliciclastic sediments are the main source for sedimentati... more <p>Nile derived siliciclastic sediments are the main source for sedimentation along the Levant continental margins. The sediments are transported along the southeastern Mediterranean coast via jet and longshore currents, mainly operating along the shelf. However, the cross shelf component of sediments transport, responsible for conveying sediments towards the upper slope, is less known. To better understand the cross-shelf vs. the longshore components of sediment transport, we studied two ~5.5 m piston cores: DOR280 and DOR350, sampled on the upper continental slope at 280 m and 350 m water depth, respectively.</p><p>We analyzed the particle size distribution (PSD) as well as the benthic-foraminiferal assemblages and their shells taphonomy, for documenting both the source and the transport mechanism of the upper continental-slope sediments. The radiocarbon sediment age at the DOR280 core-base is ~660 ±70 Cal Yrs. B.P., indicating an exceptionally high average sedimentation rate of ~800 cm/kyr. DOR280 consists of alternating two sedimentary facies: (1) Laminated (L) intervals with bimodal PSD and high ratio of allochthonous vs. autochthonous (allo/auto) foraminiferal species, characterized by a high percentage of benthic-foraminiferal broken and poorly preserved shells, indicating contribution of transported sediments originating from mid-shelf habitats. (2) Non-laminated (NL) intervals with unimodal PSD, low allo/auto ratio (<1) and low percentage of broken shells, indicating mostly <em>in-situ</em> deposition. The L intervals are interpreted as sediment laden gravity currents, possibly turbidites. Numerous centimeters-thick turbiditic events were identified, based on grain-size grading and discontinuous eroded lower stratigraphic-contacts. Sedimentation rate calculated only for the NL intervals is still exceptionally high, excluding hemipelagic sedimentation as the sole deposition. Thus, a contour bottom-current transported component is suggested for the NL sediments of DOR280 (i.e. contourites). DOR350 reveals higher sedimentation rates (age of ~350 ±80 Cal Yrs. B.P. at the core-base) and consists mostly of the L facies. Hence, the sediments of DOR350 are mostly consist of transported (by turbidities) sediments with only minor contribution of hemipelagic sedimentation or contourites.</p><p>We conclude that a hybrid contourite-turbidite system actively prevails along the Levant upper continental slope offshore Israel, apparently at water depth of less than 350 m.</p>
Sedimentary Geology, 2022
Quaternary Research, 2021
The protected Tel-Dor coastal embayment in the eastern Mediterranean preserves an unusually compl... more The protected Tel-Dor coastal embayment in the eastern Mediterranean preserves an unusually complete stratigraphic record that reveals human–environmental interactions throughout the Holocene. Interpretation of new seismic profiles collected from shallow marine geophysical transects across the bay show five seismic units were correlated with stratigraphy and age dates obtained from coastal and shallow-marine sediment cores. This stratigraphic framework permits a detailed reconstruction of the coastal system over the last ca. 77 ka as well as an assessment of environmental factors that influenced some dimensions of past coastal societies. The base of the boreholes records lowstand aeolian deposits overlain by wetland sediments that were subsequently flooded by the mid-Holocene transgression. The earliest human settlements are submerged Pottery Neolithic (8.25–7 ka) structures and tools, found immediately above the wetland deposits landward of a submerged aeolianite ridge at the mouth...
<p>The Tel-Dor embayment located along the Carmel coast provides a valuable... more <p>The Tel-Dor embayment located along the Carmel coast provides a valuable opportunity to study environmental and human interaction due to its protecting geomorphic properties that are unique for the generally linear Israeli coast. Interpretations of seismic profiles collected from transects across the bay show five seismic units that have been correlated to dated and well-analyzed sediment units in coastal cores, enabling a detailed deep time reconstruction of the coastal system over the last ~77 ka. The earliest borehole deposits are low-stand aeolian followed by terrestrial sediments including wetland remains that were subsequently flooded by the mid-Holocene transgression. Evidence of the earliest human settlement submerged Pottery-Neolithic (8.25-7 ka) remains, found immediately above the wetland deposits landward of a submerged aeolianite ridge at the mouth of the bay. The wetland deposits and Pottery-Neolithic settlement remains are at present buried by coastal sand recording middle Holocene sea-level rise and thus, suggesting that these coastal communities were displaced by sea-level transgression ca. 7.6–6.5 ka. The sedimentological and archaeological evidence identified in the stratigraphical sequence of the sheltered bay is a good example of better understanding the essential environmental changes on the shallow shelf and the coastline migration especially in bays and the human settlement adaptations to these changes. This high-resolution reconstruction based on seismic methods in the shallow water and core analysis on land combined with detailed archaeological data from the studied area provides an important addition to the puzzle of the Mediterranean story, the cradle of Western Civilizations.</p>
<p>Our study comprises a high-resolution multi-proxy investigation of a ~6 m long piston co... more <p>Our study comprises a high-resolution multi-proxy investigation of a ~6 m long piston core DOR280, sampled from the headscarp of a mapped landslide on the upper continental slope (280 m water depth) at the Dor Disturbance area, northern central Israel. The core retrieved the sediment sequence overlaying the sliding plane of the last major landsliding event. Benthic foraminiferal assemblages and taphonomy, alongside particle size distribution, were used to determine the provenance, transport distance, and reoccurrence time of mass transport events in this area. Radiocarbon ages were measured along the core revealed an age of ~600 Cal Yrs. B.P. for the core base, suggesting unexpectedly high average sedimentation rate of ~10 m/kyr, which is highest at the core top meter. Computed Tomography (CT) of DOR280 shows two alternating sedimentary facies: &#160;5 &#8211; 208 cm thick Non-Laminated (NL) and 5 &#8211; 37 cm thick Laminated (L). The L-facies sequences also include 0 &#8211; 4 cm thick High-Density Laminas (HDL). The NL-facies intervals consist of unimodal fine-sediments dominated by clay minerals. Their foraminiferal assemblage is dominated by autochthonous species (e.g. Uvigerina spp.) and low percentage of broken shells. This indicates that the NL-facies represents mostly in-situ hemipelagic deposition. The L-facies intervals also record unimodal size-distribution of fine-sediments dominated by clay minerals, but their foraminiferal assemblages are dominated by allochthonous species (e.g. Ammonia spp.) and high percentage of broken shells, indicating a contribution of transported sediments, originated from mid-shelf habitats. The HDL-facies consist of bimodal sediments comprised of fine silty-clay (~5 &#181;m) and coarse silty components (~40 &#181;m), dominated by quartz and calcite; as well as poorly preserved and broken shells of allochthonous foraminifera species. Thus, the HDL represent significant contribution of mid-shelf-origin sediments and are interpreted as turbidite-like mass transport events.</p><p>The temporal distribution of the 27 HDL events is nonrandom, revealing clusters at 59 &#177; 14 (n=9), 134 &#177; 12 (n=8), 453 &#177; 21 (n=4) and 641 &#177; 10 (n=4) years before present. These findings show prevailing cross-shelf and down slope sediments transport in the Dor Disturbance area. The HDL events can be triggered by large remote earthquakes (> 6.5), tsunami, winter storms or by sediment load that coincided with high-stand Nilotic episodes. However, mechanisms controlling the observed recent mass transport in the Dor Disturbance area still need to be studied.</p><p>DOR280 is the first piston core studied in high resolution at the upper continental slope of of the Isreali offshore. The use of benthic foraminifera assemblages and their shells taphonomy reveals the transported sediments within the core and enables an assessment regarding their source. The findings reported here identified much higher sediments accumulation rate than previously known and thus have implications to the evaluation and mitigation of marine geo-hazard in the studied area.</p>
PLOS ONE, 2020
Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of ... more Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older tsunamis on prehistoric societies has not been investigated. Here we report, based on optically stimulated luminescence chronology, the earliest documented Holocene tsunami event, between 9.91 to 9.29 ka (kilo-annum), from the eastern Mediterranean at Dor, Israel. Tsunami debris from the early Neolithic is composed of marine sand embedded within fresh-brackish wetland deposits. Global and local sea-level curves for the period, 9.91–9.29 ka, as well as surface elevation reconstructions, show that the tsunami had a run-up of at least ~16 m and traveled between 3.5 to 1.5 km inland from the palaeo-coastline. Submerged slump scars on the continental slope, 16 km west of Dor, point to the nearby “Dor-complex” as a likely cause. ...
77th EAGE Conference and Exhibition 2015, 2015
The highly oblique convergence between the North American and Caribbean plates has yielded that t... more The highly oblique convergence between the North American and Caribbean plates has yielded that the thickened crust of Bahamas banks impinges into northern Hispaniola developing a narrow band of compressive deformation (northern Hispaniola margin) and a thick foreland basin (Hispaniola-Caicos basin). Approximately 280 km of 2D MCS profiles and 17000 km2 of high-resolution, systematic swath bathymetry data were recorded in the northern Hispaniola offshore margin in November-December of 2013 (NORCARIBE cruise). This is the first time that this region is explored systematically with high-resolution multibeam bathymetry. Using new multibeam bathymetry and MCS data, combined we have studied the along- and across-strike variations of the shallower structure along a 330 km-long segment of the northern Hispaniola margin. Pronounced along-strike changes in structural style observed in the northern Hispaniola margin and Hispaniola-Caicos basin are associated with the active oblique underthrusting/indentation of the irregular boundary of the southernmost slope of the Mouchouir and Silver banks. The upper slope of the northern Hispaniola margin exhibits good economic potential associated to thick slope basins and terraces where is observable a continuous and prominent BSR. Preliminary results provide well- defined targets to carry out future exploration studies.
Quaternary Research, 2021
The protected Tel-Dor coastal embayment in the eastern Mediterranean preserves an unusually compl... more The protected Tel-Dor coastal embayment in the eastern Mediterranean preserves an unusually complete stratigraphic record that reveals human-environmental interactions throughout the Holocene. Interpretation of new seismic profiles collected from shallow marine geophysical transects across the bay show five seismic units were correlated with stratigraphy and age dates obtained from coastal and shallow-marine sediment cores. This stratigraphic framework permits a detailed reconstruction of the coastal system over the last ca. 77 ka as well as an assessment of environmental factors that influenced some dimensions of past coastal societies. The base of the boreholes records lowstand aeolian deposits overlain by wetland sediments that were subsequently flooded by the mid-Holocene transgression. The earliest human settlements are submerged Pottery Neolithic (8.25-7 ka) structures and tools, found immediately above the wetland deposits landward of a submerged aeolianite ridge at the mouth...
[This corrects the article DOI: 10.1371/journal.pone.0243619.].
The Journal of the Acoustical Society of America
6th Underwater Acoustics Conference and Exhibition
PLOS ONE, 2020
Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of ... more Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older tsunamis on prehistoric societies has not been investigated. Here we report, based on optically stimulated luminescence chronology, the earliest documented Holocene tsunami event, between 9.91 to 9.29 ka (kilo-annum), from the eastern Mediterranean at Dor, Israel. Tsunami debris from the early Neolithic is composed of marine sand embedded within fresh-brackish wetland deposits. Global and local sea-level curves for the period, 9.91-9.29 ka, as well as surface elevation reconstructions, show that the tsunami had a run-up of at least~16 m and traveled between 3.5 to 1.5 km inland from the palaeo-coastline. Submerged slump scars on the continental slope, 16 km west of Dor, point to the nearby "Dor-complex" as a likely cause. The near absence of Pre-Pottery Neolithic A-B archaeological sites (11.70-9.80 cal. ka) suggest these sites were removed by the tsunami, whereas younger , late Pre-Pottery Neolithic B-C (9.25-8.35 cal. ka) and later Pottery-Neolithic sites (8.25-7.80 cal. ka) indicate resettlement following the event. The large run-up of this event highlights the disruptive impact of tsunamis on past societies along the Levantine coast.
Conference Presentations by Omri Gadol
ASOR poster, 2020
The Mediterranean coast reflects complex long-term relationships between natural marine, terrestr... more The Mediterranean coast reflects complex long-term relationships between natural marine, terrestrial, and aeolian processes that shape this dynamic environment and have affected human settlement over time. Tel-Dor, northwest Israel, is a city mound adjacent to a bay that evolved from coastal paleosols into a marine marsh and finally a largely enclosed bay from the late-Pleistocene to present. Sediment and archaeologic records preserved at this site provide an opportunity to investigate environmental change and human-coastal interactions. Interpretations of seismics collected from transects across the bay show six seismic-units that have been correlated to dated and described sediment units in boreholes, enabling a detailed a deep-time reconstruction of the coastal system over the last ~75kyr. The earliest borehole deposits are low-stand aeolian and terrestrial sediments that were subsequently flooded by mid-Holocene transgression. Underwater excavation conducted in Dor’s south bay reveals, similar to other underwater Carmel coast sites, a submerged Pottery-Neolithic (PN; 8,250-7,800 YBP) site situated on the Holocene wetland surface. It seems that Dor’s south bay PN habitats settled on the dry wetland surface landward of an aeolianite mound benefiting from the organic rich wetland surface as well as the protective properties of the bay. The wetland deposits are buried by beach sand recording sea level rise in mid and later Holocene. The results of this study provide a framework for other coastal settings aimed at assessing the impact of natural processes on coastal societies.
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Papers by Omri Gadol
Conference Presentations by Omri Gadol