U-Pb spot analyses (LA-MC-ICPMS ) of Galilee fault-related calcite

Description

We provide U-Pb dates of syn-tectonic calcites (n=34) collected along the Galilee faulted domain. These dates suggest that the earliest NW-SE strike-slip faulting phase in Galilee was active between 25 to 7 Ma, peaking at 18.6 Ma and coeval with the onset of the DST in northern Israel. Starting from ~5 Ma, and peaking at 2 Ma, an intensive E-W normal faulting phase dominated Galilee tectonics, shaping its present basin-and-range like morphology.

Steps to reproduce

A total of 36 samples of syn-tectonic calcite precipitates were collected from the Galilee region, from which 21 were successfully dated (supplementary materials Table 2). We used U-Pb calcite dating methodology following standard routines (Nuriel et al., 2017; Oren et al., 2020). Mass-bias correction of the measured 238U/206Pb and 207Pb/206Pb ratios, was conducted in two stages: 1) using Iolite v3.5 and NIST-614 glass as the primary reference material; and 2) using WC1 (254.4 ± 6.4 Ma; Roberts et al., 2017) as a matrix-matched reference material for the drift-corrected 238U/206Pb ratio (Nuriel et al., 2017; Kylander-Clark, 2020). To ensure accuracy, we analyzed secondary reference materials including the calcite speleothem Ash-15D, previously dated by isotope-dilution methods to 2.965 Ma  0.011 2 (Nuriel et al., 2021), and other inhouse reference materials. Using a typical long-term reproducibility of 2% for individual ratios, the Ash-15D result was 2.90±0.11 Ma for ASH-15D (MSWD = 2.0, n=46, 3 rej), consistent with the reported value. Given that our long-term age accuracy is ~2%, we ensure a minimum of 2% on any reported calculated age. The ages were calculated using the IsoplotR (Vermeesch, 2018) without anchoring the common-Pb value. For disequilibrium correction we assumed 234U/238U initial activity ratio value of 1.044±0.009 and no initial Th (initial 230Th/238U = 0.001±0.0001). The former value is a weighted average of high precision 234U/238U analyses of speleothems from the nearby Zalmon (n=94; Keinan et al., 2019) and Manot (n=68; Yasur et al., 2021) caves, and is representative of local meteoric water initial values.

Institutions

• Universite de Geneve

  GE, Geneva

Categories

Funders

• Israel Science Foundation

  Jerusalem, Israel

  Grant ID: ISF‐727/16

Licence