40Ar/39Ar chronostratigraphy of late Miocene–early Pliocene continental aquatic basins in SE Galilee, Israel

Abstract

A continental inland basin extended in northern Israel and the southwest Golan Heights during the Neogene. Sedimentation of carbonates, marls, and evaporites was accompanied by massive basalt flows and by minor marine ingressions. The latter were recognized in restricted areas of the eastern Lower Galilee and the Kinnerot basin, herein termed together as the SE Galilee basin. This study aims to establish a detailed chronostratigraphic framework for ∼5 m.y. of sedimentation between the top of the latest middle Miocene Lower Basalt unit and the base of the earliest Pliocene Cover Basalt unit in the SE Galilee basin, where stratigraphic exposure and lithologic variability are maximized. Data from five outcrop sections, two boreholes, and 27 40Ar/39Ar plateau ages of volcanic rocks were used. The upper Lower Basalt was eroded from tectonically uplifted blocks. Erosion products mixed with pyroclasts were deposited in structural lows between ca. 12 and 10 Ma, forming the Umm Sabune Formation. A gradual lithological transition to the overlying well-bedded lacustrine/lagoonal Bira Formation occurred between ca. 11 and 10 Ma. The transition to the overlying freshwater Gesher Formation occurred at ca. 7 Ma, around the Tortonian-Messinian boundary; hence, the gypsum beds at this transition predated the Messinian salinity crisis. The Cover Basalt flows started between 5.1 and 4.6 Ma at different locations, contemporaneously with the deposition of the upper part of the Gesher Formation and the Fejjas Tuff unit. A newly discovered unit of conglomerates and paleosols is considered to be the continental equivalent of Messinian salinity crisis evaporite deposition. This chronostratigraphic framework provides a basis for comparison with other similar late Neogene continental basins in the Levant and for the recognition on land of the Tortonian-Messinian boundary and the impact of the Messinian salinity crisis around the Mediterranean.