Evidence for methane and hydrogen sulfide venting imprinted on a Quaternary eolianite from southern Israel

Two different and physically separated chemosynthetic communities of bacteria are responsible for the formation of the Beeri native sulfur deposit hosted in a Late Quaternary sandstone on the southern coastal plain of Israel. The enriched concentrations are distributed over an area of about 1 km², within a zone 2–3 m thick at 1–13 m below surface. Two hundred fifty meters below the sulfur deposit, sulfur-reducing bacteria, thriving on methane generated in Neogene marls, reduced the Messinian gypsum to generate hydrogen sulfide, which subaqueously vented together with methane into the siliciclastic Quaternary sequence. Another, different chemosynthetic community ofBeggiatoa-like and unidentified bacteria oxidized the hydrogen sulfide into native sulfur and secondary gypsum, alunite, and iron sulfates. The coupled chemical and bacterial processes attributed to the formation of the sulfur deposit at Beeri are strikingly similar to the processes occurring today in the context of submarine hydrocarbon vents associated with the salt diapirs in the Gulf of Mexico.     

Low‐temperature thermochronology of francolite: Insights into timing of Dead Sea Transform motion

Cambrian siliciclastic sequences along the Dead Sea Transform (DST) margin in southern Israel and southern Jordan host both detrital fluorapatite [D‐apatite] and U‐rich authigenic carbonate‐fluorapatite (francolite) [A‐apatite]. D‐apatite and underlying Neoproterozoic basement apatite yield fission‐track (FT) data reflecting Palaeozoic–Mesozoic sedimentary cycles and epeirogenic events, and dispersed (U–Th–Sm)/He (AHe) ages. A‐apatite, which may partially or completely replace D‐apatite, yields an early Miocene FT age suggesting formation by fracturing, hydrothermal fluid ascent and intra‐strata recrystallisation, linked to early DST motion. The DST, separating the African and Arabian plates, records ~105 km of sinistral strike‐slip displacement, but became more transtensional post‐5 Ma. Helium diffusion measurements on A‐apatite are consistent with thermally activated volume diffusion, indicating Tc ~52 to 56 ± 10°C (cooling rate 10°C/Ma). A‐apatite AHe data record Pliocene cooling (~35 to 40°C) during the transtensional phase of movement. This suggests that timing of important milestones in DST motion can be discerned using A‐apatite low‐temperature thermochronology data alone.     

The Triassic of the southern margin of the Tethys in the Levant and its correlation across the Jordan Rift Valley

The Triassic of the Levantine region consists of four sedimentary cycles: I. Scythian — Lower Anisian; II. Early Upper Anisian; III. Late Upper Anisian — Carnian; IV. Late Carnian — Norian.Regional biofacial affinities point to the existance of a western Tethyan Werfen facies (cycle I), a sephardic biofacies (cycles II and III) and a rather alpinotype platform facies (cycle IV). A correlation across the Jordan Rift Valley is suggested, primarily based on bio- and lithostratigraphic evidence of the Permo-Triassic rocks. The stratigraphic implications of this correlation support the existance of a left lateral strike slip along the Jordan Rift Valley.

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Zusammenfassung Die Trias im Levant ist in vier Sedimentationszyklen gegliedert: I. Skythian — Unteres Anisian; II. Oberes Anisian; III. Oberes Anisian — Karnian; IV. Oberes Karman — Norian.Die regionalen Faziesbeziehungen deuten auf das Vorhandensein einer Westtethyalen Werfener Fazies (Zyklus I), einer West- und Südtethyalen Sephardischen Fazies (Zyklen II und III) und einer eher alpinotypischen Plattformfazies (Zyklus IV).Eine Korrelation der permisehen und untertriadischen Gesteine auf beiden Seiten des Jordantales wird vorgeschlagen. Die stratigraphischen Folgerungen dieser Korrelation unterstützen die Existenz einer linken Transversalverschiebung entlang des Jordantal Rifts.

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Résumé Le Trias du Levant comprend quatre cycles sédimentaires: I. Scythien-Anisien inférieur; II. Anisien supérieur; III. Anisien supérieur — Carnien; IV. Carnien supérieur — Norien.La succession des biofaciès débute par le faciès Werfénien, qui englobait pratiquement la Téthys occidentale éotriasique toute entière (cycle I). Dans le courant du Mésotrias, le faciès Sépharade s'étend aux marges méridionales et occidentales de la Téthys (cycles II et III), tandis qu'un faciès de plateforme d'affinité plutôt alpine représente le Trias terminal (cycle IV).Une corrélation des séries Permo-Eotriasiques du Néguev et de Transjordanie est proposée. Les implications stratigraphiques de cette corrélation appuient l'existence d'un coulissage sénestre tout au long du Rift de la vallée du Jourdain.

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Prediction of regional-scale groundwater recharge and nitrate storage in the vadose zone: A comparison between a global model and a regional model

Extensive nitrogen loads at the soil surface exceed plant uptake and soil biochemical capacity, and therefore lead to nitrogen accumulation in the deep vadose zone. Studies have shown that stored nitrogen in the vadose zone can eventually reach the water table and affect the quality of groundwater resources. Recently, global scale models have been implemented to quantify nitrate storage and nitrate travel time in the vadose zone. These global models are simplistic and relatively easy to implement and therefore facilitate analysis of the considered transport processes at a regional scale with no further requirements. However, the suitability of applying these models at a regional scale has not been tested. Here, we evaluate, for the first time, the performance and utility of global scale models at the regional scale. Applied to the Loess Plateau of China, we compare estimates of groundwater recharge and nitrate storage derived from global scale models with results from a regional scale approach utilizing the Richards and advection-dispersion equations. The estimated nitrate storage was compared to nitrate observations collected in the deep vadose zone (>50 m) at five sites across the Loess Plateau. Although both models predict similar spatial patterns of nitrate storage, the recharge fluxes were three times smaller and the nitrate storage was two times higher compared with the regional model. The results suggest that global scale models are a potentially useful screening tool, but require refinement for local scale applications.