We present a formulation for mechanical modeling of interaction between fracture and fluid flow. ... more We present a formulation for mechanical modeling of interaction between fracture and fluid flow. The new model combines the classical Biot's poroelastic theory together with a damage rheology model. The theoretical analysis based on the thermodynamic principles, leads to a system of coupled kinetic equations for the evolution of damage and porosity. We generalize the widely used permeability (k)-porosity (phi
We present a formulation for mechanical modeling of interaction between fracture and fluid flow. ... more We present a formulation for mechanical modeling of interaction between fracture and fluid flow. The new model combines the classical Biot's poroelastic theory with a damage rheology model. The theoretical analysis based on the thermodynamic principles, leads to a system of coupled kinetic equations for the evolution of damage and porosity. Competition between two thermodynamic forces, one related to porosity
A striking surficial feature of the Hula basin (HB) is the inversion of the rhomb shape: the cont... more A striking surficial feature of the Hula basin (HB) is the inversion of the rhomb shape: the contour of the young basin fill follows a rhomb consistent with dextral strike slip whereas the basin subsides along the sinistral Dead Sea transform (DST). This work aims at explaining the inversion of the rhomb shape. Recently reinterpreted seismic and gravimetric data identify fault branching inside the HB. The new findings support our hypothesis of evolving fault branches during basin formation and subsidence. The inversion is related to branching of DST that postdates basin initiation. Such branching is inferred for the Hula basin from several lines of evidence (geophysics together with fault and earthquake mechanics). We examine this hypothesis using a clay model where branching appears after initial subsidence. Indeed the initial rhomb is consistent with the pull apart model for sinistral slip, and branching inverts the rhomb. We conclude that the contour of basin fill can be an indic...
ABSTRACT Experimental techniques to determine paleomagnetic field intensity are based on a theore... more ABSTRACT Experimental techniques to determine paleomagnetic field intensity are based on a theoretical framework that is valid only for single-domain (SD) ferromagnetic particles. Yet, most of the available materials exhibit distinctly non-SD properties. Hence, designing a robust paleointensity methodology for non-SD is a fundamental challenge in paleomagnetism. Here we test the IZZI Thellier absolute paleointensity technique on slag material that has properties of small MD. The test has two purposes: 1) to describe the characteristic non-SD patterns occurring in Arai plots, and 2) to identify the optimal approach in interpreting non-SD behavior. We produced 4 synthetic re-melted slag samples with identical magneto-mineralogical properties under field intensities of 20, 40, 60 and 80 μT. We ran three batches of IZZI paleointensity experiments on 10 specimens per samples. The IZZI experiments were designed to identify the dependency of the results on the ratio and the angle between the field used in the paleointensity experiment (BTRM) and the field in which the NRM was acquired (BNRM). The results demonstrate different types of Arai plots, systematically dependent on the angle and the proportion between BTRM and BNRM. Straight-line Arai plots occur when the two fields are parallel and equal, and seem to always give the 'true' slope. Convex curves occur when BTRM is parallel and significantly stronger than BNRM. Concave curves occur in all the other cases and yield two end-case slopes that are always different from the 'true' slope. The zigzags of the Arai plot increase with the proportion between BTRM and BNRM, and as the angle between BTRM and BNRM approaches 90°. We test the accuracy of the commonly used data analysis approach of best fitting line through a chosen segment of the Arai plot. We conclude that best fitting line in curved plots cannot provide robust paleointensity estimates. However, the two 'end-case' slopes in concave curves can provide adequate constraints for the 'true' value. We introduce a new bootstrap procedure to calculate a 95% confidence interval of the result. We substantiate the new procedure by conducting two independent tests. The first uses synthetic re-melted slag produced under known field intensities - 3 SD samples and 4 non-SD samples. The second compares paleointensity determinations from archaeological slag samples of the same age - 34 SD samples and 10 non-SD samples. The two tests suggest that the bootstrap technique is an optimal approach for non-ideal dataset.
ABSTRACT The ICDP funded Dead Sea Deep Drilling Project (DSDDP) recovered the longest and most co... more ABSTRACT The ICDP funded Dead Sea Deep Drilling Project (DSDDP) recovered the longest and most complete paleo-environmental record in the Middle East, drilling holes in a deep and a shallow site extending to ~450 meters. The Dead Sea expands during the glacials and contracts during interglacials, and the sediments are an archive of the evolving climatic conditions. During glacials the sediments comprise intervals of marl (aragonite, gypsum and detritus) and during interglacials they are salts and marls. We estimate that the deep site core spans ~200 kyr (to early MIS 7). A dramatic discovery is a ~40 cm interval of rounded pebbles at ~235 m below the lake floor, the only clean pebbly unit in the entire core. It appears to be a beach layer, near the deepest part of the Dead Sea, lying above ~35 meters of mainly salt. If it is a beach layer, it implies an almost complete dry-down of the paleo-Dead Sea. The pebble layer lies within the last interglacial interval. Our initial attempt to estimate the age of the possible dry down shows an intriguing correlation between the salt-mud stratigraphy of the Dead Sea core and the oxygen isotope record of Soreq Cave, whereby excursions to light oxygen in the speleothems correspond to periods of salt deposition. Through this comparison, we estimate that the dry down occurred during MIS 5e. The occurrence of ~35 meters of mainly salt along with the pebble layer demonstrates a severe dry interval during MIS 5. This observation has implications for the Middle East today, where the Dead Sea level is dropping as all the countries in the area use the runoff. GCM models indicate a more arid future in the region. The core shows that the runoff nearly stopped during a past warm period without human intervention.
... Turekian (1993). Recently, Stoll and Schrag (1998) demonstrated the importance of carbonate m... more ... Turekian (1993). Recently, Stoll and Schrag (1998) demonstrated the importance of carbonate mineral recrystallization, induced by exposure of continental shelves during glacial periods, to the oceanic Sr budget. They concluded ...
This work investigates slip rate evolution over time along one large strike-slip fault, the Dead ... more This work investigates slip rate evolution over time along one large strike-slip fault, the Dead Sea Transform (DST), which is the 1000-km long plate boundary between the Arabia plate and the Sinai sub-plate. We focus on the Wadi Araba fault, the southernmost segment of the DST. No agreement has been reached yet about the slip rate of the DST. Proposed
We present a formulation for mechanical modeling of interaction between fracture and fluid flow. ... more We present a formulation for mechanical modeling of interaction between fracture and fluid flow. The new model combines the classical Biot's poroelastic theory together with a damage rheology model. The theoretical analysis based on the thermodynamic principles, leads to a system of coupled kinetic equations for the evolution of damage and porosity. We generalize the widely used permeability (k)-porosity (phi
We present a formulation for mechanical modeling of interaction between fracture and fluid flow. ... more We present a formulation for mechanical modeling of interaction between fracture and fluid flow. The new model combines the classical Biot's poroelastic theory with a damage rheology model. The theoretical analysis based on the thermodynamic principles, leads to a system of coupled kinetic equations for the evolution of damage and porosity. Competition between two thermodynamic forces, one related to porosity
A striking surficial feature of the Hula basin (HB) is the inversion of the rhomb shape: the cont... more A striking surficial feature of the Hula basin (HB) is the inversion of the rhomb shape: the contour of the young basin fill follows a rhomb consistent with dextral strike slip whereas the basin subsides along the sinistral Dead Sea transform (DST). This work aims at explaining the inversion of the rhomb shape. Recently reinterpreted seismic and gravimetric data identify fault branching inside the HB. The new findings support our hypothesis of evolving fault branches during basin formation and subsidence. The inversion is related to branching of DST that postdates basin initiation. Such branching is inferred for the Hula basin from several lines of evidence (geophysics together with fault and earthquake mechanics). We examine this hypothesis using a clay model where branching appears after initial subsidence. Indeed the initial rhomb is consistent with the pull apart model for sinistral slip, and branching inverts the rhomb. We conclude that the contour of basin fill can be an indic...
ABSTRACT Experimental techniques to determine paleomagnetic field intensity are based on a theore... more ABSTRACT Experimental techniques to determine paleomagnetic field intensity are based on a theoretical framework that is valid only for single-domain (SD) ferromagnetic particles. Yet, most of the available materials exhibit distinctly non-SD properties. Hence, designing a robust paleointensity methodology for non-SD is a fundamental challenge in paleomagnetism. Here we test the IZZI Thellier absolute paleointensity technique on slag material that has properties of small MD. The test has two purposes: 1) to describe the characteristic non-SD patterns occurring in Arai plots, and 2) to identify the optimal approach in interpreting non-SD behavior. We produced 4 synthetic re-melted slag samples with identical magneto-mineralogical properties under field intensities of 20, 40, 60 and 80 μT. We ran three batches of IZZI paleointensity experiments on 10 specimens per samples. The IZZI experiments were designed to identify the dependency of the results on the ratio and the angle between the field used in the paleointensity experiment (BTRM) and the field in which the NRM was acquired (BNRM). The results demonstrate different types of Arai plots, systematically dependent on the angle and the proportion between BTRM and BNRM. Straight-line Arai plots occur when the two fields are parallel and equal, and seem to always give the 'true' slope. Convex curves occur when BTRM is parallel and significantly stronger than BNRM. Concave curves occur in all the other cases and yield two end-case slopes that are always different from the 'true' slope. The zigzags of the Arai plot increase with the proportion between BTRM and BNRM, and as the angle between BTRM and BNRM approaches 90°. We test the accuracy of the commonly used data analysis approach of best fitting line through a chosen segment of the Arai plot. We conclude that best fitting line in curved plots cannot provide robust paleointensity estimates. However, the two 'end-case' slopes in concave curves can provide adequate constraints for the 'true' value. We introduce a new bootstrap procedure to calculate a 95% confidence interval of the result. We substantiate the new procedure by conducting two independent tests. The first uses synthetic re-melted slag produced under known field intensities - 3 SD samples and 4 non-SD samples. The second compares paleointensity determinations from archaeological slag samples of the same age - 34 SD samples and 10 non-SD samples. The two tests suggest that the bootstrap technique is an optimal approach for non-ideal dataset.
ABSTRACT The ICDP funded Dead Sea Deep Drilling Project (DSDDP) recovered the longest and most co... more ABSTRACT The ICDP funded Dead Sea Deep Drilling Project (DSDDP) recovered the longest and most complete paleo-environmental record in the Middle East, drilling holes in a deep and a shallow site extending to ~450 meters. The Dead Sea expands during the glacials and contracts during interglacials, and the sediments are an archive of the evolving climatic conditions. During glacials the sediments comprise intervals of marl (aragonite, gypsum and detritus) and during interglacials they are salts and marls. We estimate that the deep site core spans ~200 kyr (to early MIS 7). A dramatic discovery is a ~40 cm interval of rounded pebbles at ~235 m below the lake floor, the only clean pebbly unit in the entire core. It appears to be a beach layer, near the deepest part of the Dead Sea, lying above ~35 meters of mainly salt. If it is a beach layer, it implies an almost complete dry-down of the paleo-Dead Sea. The pebble layer lies within the last interglacial interval. Our initial attempt to estimate the age of the possible dry down shows an intriguing correlation between the salt-mud stratigraphy of the Dead Sea core and the oxygen isotope record of Soreq Cave, whereby excursions to light oxygen in the speleothems correspond to periods of salt deposition. Through this comparison, we estimate that the dry down occurred during MIS 5e. The occurrence of ~35 meters of mainly salt along with the pebble layer demonstrates a severe dry interval during MIS 5. This observation has implications for the Middle East today, where the Dead Sea level is dropping as all the countries in the area use the runoff. GCM models indicate a more arid future in the region. The core shows that the runoff nearly stopped during a past warm period without human intervention.
... Turekian (1993). Recently, Stoll and Schrag (1998) demonstrated the importance of carbonate m... more ... Turekian (1993). Recently, Stoll and Schrag (1998) demonstrated the importance of carbonate mineral recrystallization, induced by exposure of continental shelves during glacial periods, to the oceanic Sr budget. They concluded ...
This work investigates slip rate evolution over time along one large strike-slip fault, the Dead ... more This work investigates slip rate evolution over time along one large strike-slip fault, the Dead Sea Transform (DST), which is the 1000-km long plate boundary between the Arabia plate and the Sinai sub-plate. We focus on the Wadi Araba fault, the southernmost segment of the DST. No agreement has been reached yet about the slip rate of the DST. Proposed
"Flower structures" in seismic profiles are commonly interpreted as indicators of strike-slip fau... more "Flower structures" in seismic profiles are commonly interpreted as indicators of strike-slip faults. We investigate the generation and growth of flower structures by combining analog laboratory experiments with a 3D seismic survey. The laboratory models include layered sequences of silicon putty and clay above two rigid blocks subjected to strike-slip motion. Model surface topography is frequently recorded by 3D laser scanning and photography. Elongated, gentle ridges developed at ~45° to basement strike-slip fault when a bi-layer of greased clay and silicon was emplaced hard clay block; we refer to these elongated ridges as 'wrinkles'. With increasing fault displacement, the ratio between wrinkle length and width increases. As fault displacement progresses, tear faults develop through the wrinkles; from this stage, the strike-slip becomes the dominant structural feature influencing the deformation of covering layers. Field study in the Dead Sea Transform (north of Sea of Galille), suggest the existence of a strike-slip fault covered by young sedimentary and volcanic strata. We conducted a high resultion 3D seismic survey using 240 channels and 744 shot points covering an area of 300X200m to image this buried fault, and we identified elongated structures trending ~25° NE to the mapped strike-slip fault. We mapped these structures using time slices, spatial interpretation, and seismic attributes and recognized a wrinkle on a basalt flow reflector at a depth of ~100m. The SE wrinkle flank displays an angular disconformity with apparent horizontal displacenemt of 45m. The displacement appears ~80m east of the surface trace of the fault with paleoseismic trench evidence of young activity (Marco et al. 2005); this observation suggests that the activity zone migrated westward during the last 1my. The displacement of 45m is regarded a minimum value due to the cyclic nature of wrinkling. We suggest that wrinkles are the expression of positive flower structures in 2D seismic profiles across strike slip faults. Negative flower structures may be the manifestation of tear faults and extension along the wrinkle axis. Hence, flower structures do not necessarily indicate transpression or transtension.
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