TY - JOUR
T1 - Re-evaluation of the epicontinental paradigm for genesis of the Triassic succession in southern Israel
AU - Benjamini, Chaim
AU - Korngreen, Dorit
AU - Bialik, Or
PY - 2014/5/1
Y1 - 2014/5/1
N2 - The Middle and Late Triassic succession in southern Israel has been
regarded as part of the epicontinental marginal marine zone of the
Gondwanan margin. This scenario is at odds with field evidence in
southern Israel. The clastic-dominated Pelsonian succession and the
carbonate-evaporite late Anisian to Carnian successions were largely
marine low energy settings below storm wave base. δ13C values
occur within a range characteristic of the Triassic open marine
environment. Some deeper settings were marked by downslope transport to
the deep ramp. Sea level falls are evidenced by shallowing to proximal
subtidal zones of wave or storm activity. Subaerial exposure features
are absent except in the late Pelsonian, when rate of sedimentation of
continental clastics briefly exceeded subsidence, and at the termination
of tectonic subsidence in the Carnian, when evaporites were superseded
by prograding microbialites. Early Pelsonian mixed
siliciclastic/carbonate sediments initially accumulated below storm wave
base. Sea level fall and aridization in the hinterland led briefly to
reduction of siliciclastic influx, This transition was in the lower
--Balatonicus ammonoid zone, correlative to a Bithynian/ Pelsonian humid
pulse followed by a Pelsonian semi-arid regime recorded elsewhere in the
Tethys. Subsequent increased rainfall and concomitant siliciclastic
influx caused delta progradation and inhibition of carbonates. The delta
front zone was mostly below or near fair weather wave base, with the
proximal subtidal zone reached only at the time of sea level fall.
Rising sea level of the later Pelsonian led to flooding of
clastic-dominated deltaic lagoons and the increasingly
carbonate-dominated, fully marine settings of the Illyrian and
Fassanian. The Longobardian stromatolitic and incipient evaporite facies
indicate both lowered sea-level and climate change to aridity. Ocean
connectivity fluctuated between deep hypersaline waters pooled behind a
deep barrier at sea-level highstands, and stromatolite-dominated
biofacies during lowstands. The low overall rate of sedimentation was
consistent with condensation. In the Longobardian, thin clastic-type
evaporite horizons are interbedded with fossiliferous carbonates.
Evaporites vs. carbonates formed on the proximal shallow margins of the
basin according to whether climate was arid or humid, and were
transported downslope. An early Carnian carbonate-free interval
indicates a humid pulse, followed by development of thick cycles of
shale, dolomite, and laminated gypsarenite, the latter representing
resedimented evaporite crystals on the deep ramp and toe of slope of a
subsiding basin. Subsidence terminated in aggrading subtidal
microbialites beneath a major regional truncation surface. Termination
of differential subsidence in the latest Carnian - Norian is coeval
across Israel from south to north, but coincides with establishment of a
reefal succession on the northwestern Israel coast. The Triassic
succession of southern Israel formed within a varied bathymetric
shelf-edge depositional setting of variably restricted basins and highs,
responding to eustatic sea level changes, remote climate conditions and
events, and local and regional tectonic movements. The dominance of
deep, open water settings calls into question the extensive ramp- or
platform- like nature assumed for epicontinental marine environments of
the Triassic in Israel.
AB - The Middle and Late Triassic succession in southern Israel has been
regarded as part of the epicontinental marginal marine zone of the
Gondwanan margin. This scenario is at odds with field evidence in
southern Israel. The clastic-dominated Pelsonian succession and the
carbonate-evaporite late Anisian to Carnian successions were largely
marine low energy settings below storm wave base. δ13C values
occur within a range characteristic of the Triassic open marine
environment. Some deeper settings were marked by downslope transport to
the deep ramp. Sea level falls are evidenced by shallowing to proximal
subtidal zones of wave or storm activity. Subaerial exposure features
are absent except in the late Pelsonian, when rate of sedimentation of
continental clastics briefly exceeded subsidence, and at the termination
of tectonic subsidence in the Carnian, when evaporites were superseded
by prograding microbialites. Early Pelsonian mixed
siliciclastic/carbonate sediments initially accumulated below storm wave
base. Sea level fall and aridization in the hinterland led briefly to
reduction of siliciclastic influx, This transition was in the lower
--Balatonicus ammonoid zone, correlative to a Bithynian/ Pelsonian humid
pulse followed by a Pelsonian semi-arid regime recorded elsewhere in the
Tethys. Subsequent increased rainfall and concomitant siliciclastic
influx caused delta progradation and inhibition of carbonates. The delta
front zone was mostly below or near fair weather wave base, with the
proximal subtidal zone reached only at the time of sea level fall.
Rising sea level of the later Pelsonian led to flooding of
clastic-dominated deltaic lagoons and the increasingly
carbonate-dominated, fully marine settings of the Illyrian and
Fassanian. The Longobardian stromatolitic and incipient evaporite facies
indicate both lowered sea-level and climate change to aridity. Ocean
connectivity fluctuated between deep hypersaline waters pooled behind a
deep barrier at sea-level highstands, and stromatolite-dominated
biofacies during lowstands. The low overall rate of sedimentation was
consistent with condensation. In the Longobardian, thin clastic-type
evaporite horizons are interbedded with fossiliferous carbonates.
Evaporites vs. carbonates formed on the proximal shallow margins of the
basin according to whether climate was arid or humid, and were
transported downslope. An early Carnian carbonate-free interval
indicates a humid pulse, followed by development of thick cycles of
shale, dolomite, and laminated gypsarenite, the latter representing
resedimented evaporite crystals on the deep ramp and toe of slope of a
subsiding basin. Subsidence terminated in aggrading subtidal
microbialites beneath a major regional truncation surface. Termination
of differential subsidence in the latest Carnian - Norian is coeval
across Israel from south to north, but coincides with establishment of a
reefal succession on the northwestern Israel coast. The Triassic
succession of southern Israel formed within a varied bathymetric
shelf-edge depositional setting of variably restricted basins and highs,
responding to eustatic sea level changes, remote climate conditions and
events, and local and regional tectonic movements. The dominance of
deep, open water settings calls into question the extensive ramp- or
platform- like nature assumed for epicontinental marine environments of
the Triassic in Israel.
M3 - תקציר הצגה בכנס
SN - 1029-7006
VL - 16
SP - 16544
JO - Geophysical Research Abstracts
JF - Geophysical Research Abstracts
ER -