Event E at Nahal Ze'elim site ZA-1 a ~10 cm thick Type IV seismite with an estimated intensity of 9. ZA-1 was the first site in Nahal Ze'elim to be systematically investigated for Holocene paleoseismicity and established the basic framework for correlating earthquake-generated deformation structures with the historical earthquake record of the Dead Sea region. The site occupies a relatively landward position within the Ze'elim Terrace compared with the more seaward exposures examined in later studies such as Kagan et al. (2011). As a result, ZA-1 contains a greater proportion of shoreline and nearshore facies, whereas the later studies accessed more seaward sections characterized by thicker and more continuous lacustrine deposition. These more offshore settings preserved a larger number of earthquake-induced deformation horizons, resulting in a more complete Holocene paleoseismic record than was available at ZA-1.
Event E occurs within the northern gully at site ZA-1, ~470 cm above the base of the studied section, and is hosted within the Ze'elim Formation, a sequence of laminated aragonite and detrital sediments deposited in the paleo-Dead Sea following the retreat of Lake Lisan. The deformed horizon occurs in the upper part of the ZA-1 section above the major mid-first millennium CE erosional unconformity that removed much of the record between the ~4th and ~11th centuries CE. Event E is expressed as a mixed layer composed of disturbed fine-grained sediment and fragmented aragonite laminae. Like the older seismites in the sequence, Event E is interpreted as the product of earthquake-induced liquefaction, fluidization, brecciation, and resuspension of unconsolidated sediment at the sediment-water interface. The sharp contacts of the mixed layer and the preservation of undisturbed sediments above it indicate that the deformation occurred syndepositionally rather than as a result of later disturbance.
The age of Event E was constrained using three radiocarbon determinations obtained from the mixed layer itself. These samples yielded ages of 690 ± 30 (sample KIA3217), 700 ± 30 (sample KIA3218), and 760 ± 30 (sample KIA3219) radiocarbon years BP. The resulting calibrated age range for Event E is 1220-1390 CE ( 2σ). Event E is immediately overlain by a 20-30 cm thick detrital unit that separates it from Event F, which was dated to a calibrated age of 1270-1400 CE ( 2σ). Based on estimated sedimentation rates of approximately 3-13 mm yr-1, this interval represents roughly 20-100 years of deposition. Although the calibrated age ranges of Events E and F overlap and are statistically indistinguishable, their stratigraphic order and the intervening sedimentary interval suggest that the two mixed layers record separate earthquakes.
Based on this chronology, Ken-Tor et al. (2001a) correlated Event E with the 1212 CE earthquake and Event F with the 1293 CE earthquake. They noted that the amount of sediment separating the two mixed layers is consistent with the approximately 81-year interval between the historical earthquakes, providing additional support for assigning the lower horizon to 1212 CE and the upper horizon to 1293 CE. This interpretation was retained by Ken-Tor et al. (2001b), who argued that the close agreement between the radiocarbon chronology, stratigraphic relationships, and historical earthquake record indicates that the organic material incorporated into the mixed layers experienced only limited transport and residence times prior to deposition. An alternative possibility is that Event E was produced by one of the 1202 CE earthquakes. Agnon et al. (2006) observed at En Gedi that the 1212 CE seismite appears to overprint the 1202 CE seismite, raising the possibility that a similar process occurred at Nahal Ze'elim, where evidence of the earlier event may have been obscured or incorporated into the younger deformation horizon.
- Fig. 1c Oblique aerial photo of
SW Dead Sea showing Masada and Zeelim Plain from Agnon et al. (2006)
An oblique air photo looking southward at the southwestern part of the Dead Sea showing faults (solid lines) and locations of studied late Pleistocene sections M and PZ. MFZ—Masada Fault Zone. The photo was taken in 1940 when the lake level was 395 m below sea level. The current level is 420 m below sea level; additional area has emerged, including the Ze' elim fan outcrop.
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Agnon et al. (2006)- Nahal Ze'elim outcrop areas
in Google Earth
ZA-I is a guesstimate
click on image to explore this site on a new tab in Google Earth- Figure 2 Annotated Lithosection
of ZA-1 with interpreted ages noted from Ken-Tor et al. (2001a)
The lithology and chronology of a composite section exposed in Ze'elim Plain. The section is described from two outcrops exposed in different gullies 300 m apart. The correlation between the outcrops is based on the sedimentary sequence, laminae counting, and 14C dates. Ages presented in 14C years B.P. Deformed units (mixed layers and liquefied sands) are marked by capital letters.
slightly modified by JW - red dates as interpreted by JW added
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Ken-Tor et al. (2001a)- Figure 8 Age Model for ZA-1
from Agnon et al. (2006)
A modified age model for the Ze'elim section studied in outcrop (Ken-Tor et al., 2001a) and drill core (Migowski et al., 2004). A–H denote events discussed in the text. The present model was constrained by two rules:
(1) each event horizon (top of each intraclast breccia) matches a historical earthquake of notice.
(2) each continuous deposition segment shows a uniform deposition rate.
Two outcomes support the model. Two of the breccia layers match pairs of earthquakes (64–31 BCE; 1202–1210 CE) such that the earlier event horizon is within the breccia layer and the later event matches the top. With these assignments for the event horizons, the model gives a uniform sedimentation rate of 0.5 cm/yr during the three periods separated by hiatuses.
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Agnon et al. (2006)- Figure 3 Age Model for ZA-1
from Ken-Tor et al. (2001a)
Table 1
- Chronology of the deformed units (seismites) in the Ze'elim section. Solid dots represent 14C ages in years B.P. Error bars represent the ranges in the calibrated ages (2σ) of all samples in each stratigraphic horizon. Vertical thin lines represent historical earthquakes in the Dead Sea area, which were correlated to the deformed units in the Ze'elim section. Horizontal dashed arrows are drawn from the deformed units (listed in capital letters) to the correlative earthquakes.
- Sedimentation rates calculated for the lower part of the composite section. The longest calibrated range was used for calculating the minimum sedimentation rate, and the shortest range for calculating the maximum sedimentation rate. Two clear unconformities are evident. The upper one is dated to 1290-1420 A.D., and the lower one to 1030-1210 A.D. The lower unconformity is marked by a sharp decrease in the sedimentation rate. Vertical dashed lines represent earthquakes that lie within the sedimentological hiatuses. Sedimentation rate of the upper part of the section was not calculated because datable samples were insufficient.
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Ken-Tor et al. (2001a)- Table 1 Radiocarbon Table
from Ken-Tor et al. (2001b)
AMS results of 14C dating. Calibrated dates according to Stuiver et al. (1998). The samples are listed by stratigraphic height, from top to bottom. Samples collected from seismite units are shown in bold.
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Ken-Tor et al. (2001b)- Table 1 Radiocarbon Table
from Ken-Tor et al. (2001a)
AMS Results of Radiocarbon Dating
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Ken-Tor et al. (2001a)- Table 2 Refined Radiocarbon Table
from Ken-Tor et al. (2001a)
The 14C Chronology of the Deformed Layers (Seismites)
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Ken-Tor et al. (2001a)- Figure 4e Calibrated Radiocarbon Ages
from Ken-Tor et al. (2001b)
Chronology of the seismite record
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Ken-Tor et al. (2001b)- Fig. 2 Sediment Core comparisons
and Age-Depth Models for Ein Gedi, En Feshka, and Nahal Zeelim from Migowski et al. (2004)
Lithology of the sediment cores and the established age-depth models of the different profiles. The Ze'elim coring profile is paralleled by the Ze'elim gully wall. The Ein Gedi chronology is based on 20 radiocarbon dates and on the varve-counted section (black line) in the upper part.
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Migowski et al. (2004)- Correlated Trench Logs used
to Produce Composite ZA-1 Litholog from Revital Bookman (née Ken-Tor)
The final lithosection of Bookman (née Ken-Tor) is a composite litholog derived from multiple sites located up to approximately 300 m apart. ZA-1 refers to the location from which a large portion of the composite lithosection was constructed. More landward gullies were used to capture the most recent earthquakes, including Events G (1834 CE) and H (1927 CE). Bookman referred to site ZA-1 as Site 2.
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Revital Bookman (née Ken-Tor)