Tectonophysics 371 (2003) 223–241 www.elsevier.com/locate/tecto Morphological and structural relations in the Galilee extensional domain, northern Israel A. Matmona,b,*, S. Wdowinskic, J.K. Hallb a Department of Geology, Hebrew University, Jerusalem 91904, Israel b Geological Survey of Israel, 30 Malkhe Yisrael Street, Jerusalem 95501, Israel c Department of Geophysics and Planetary Sciences, Tel Aviv University, Tel Aviv, 69978, Israel Received 6 December 2001; accepted 11 June 2003 Abstract The Lower Galilee and the Yizre’el Valley, northern Israel, are an extensional domain that has been developing since the Miocene, prior and contemporaneously to the development of the Dead Sea Fault (DSF). It is a fan-shaped region bounded in the east by the N–S trending main trace of the DSF, in the north by the Bet-Kerem Fault system, and in the south by the NW– SE trending Carmel Fault. The study area is characterized by high relief topography that follows fault-bounded blocks and flexures at a wavelength of tens of km. A synthesis of the morphologic–structural relations across the entire Galilee region suggests the following characteristics: (1) Blocks within the Lower Galilee tilt toward both the southern and northern boundaries, forming two asymmetrical half-graben structures, opposite facing, and oblique to one another. (2) The Lower Galilee’s neighboring blocks, which are the Upper Galilee in the north and the Carmel block in the southwest, are topographically and structurally uplifted and tilted away from the Lower Galilee. (3) The southern half-graben, along the Carmel Fault, is topographically and structurally lower than the northern one. Combining structural and geological data with topographic analysis enables us to distinguish several stages of structural and morphological development in the region. Using a semi-quantitative evolutionary model, we explain the morpho-structural evolution of the region. Our results indicate that the Galilee developed as a set of two isostatically supported opposite facing half-grabens under varying stress fields. The southern one had started developing as early as the early Miocene prior to the formation of the DSF. The northern and younger one has been developing since the middle Pliocene as part of the extension process in the Galilee. Elevation differences between the two half-grabens and their bounding blocks are explained by differences in isostatic subsidence due to sedimentary loading and uplift of the northern half-graben due to differential influences of the regional folding. D 2003 Elsevier B.V. All rights reserved. Keywords: Tilted blocks; Normal faults; Galilee; Rift margins; Extension 1. Introduction The Galilee region is located in northern Israel between the Mediterranean and the Dead Sea Fault * Corresponding author. Current address: U.S. Geological Survey, 345 Middlefield Road MS #977, Menlo Park, CA, 94025, (DSF), which is the boundary separating between the USA. Sinai and Arabian plates (Garfunkel, 1970, 1981; Fig. E-mail address: [email protected] (A. Matmon). 1). The present structure of the Galilee has been 0040-1951/03/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0040-1951(03)00237-3 224 A. Matmon et al. / Tectonophysics 371 (2003) 223–241 Fig. 1. General location map (Israel grid). Database: Hall (1993, 1996). Inset: eastern Mediterranean tectonic setting. Dead Sea Faults (thin dashed lines) are drawn schematically. A. Matmon et al. / Tectonophysics 371 (2003) 223–241 225 developing since the Miocene, prior and contempora- structural and topographic characteristics of the neously to the development of the DSF (Freund, bounding blocks of the Lower Galilee. 1970). Understanding the development and evolution In this study, we systematically explore and char- of the Galilee provides important observations regard- acterize the relations between topography and struc- ing the tectonic and structural conditions that existed in ture in the Lower Galilee and Yizre’el Valley and their the region prior, during, and after the formation of the bounding blocks. Our study expands beyond the DSF. Furthermore, the Galilee is the only extensional extensional Lower Galilee and Yizre’el Valley, and domain that extends well beyond the Dead Sea Fault’s includes the neighboring Upper Galilee and Carmel narrow rift margins. Hence, studying the structural and blocks. The southwestern boundary of the extensional morphological relations between the Galilee and the domain is well defined by a single fault, the Carmel Dead Sea Fault provide better understanding of the Fault. However, the southeastern boundary is not as coupling between transcurrent movements and adja- well defined. It diffuses into several parallel faults, cent diffuse extensional deformation. Such extensional which form the northeastern Samaria and the Gilboa domains are also observed along other continental blocks. We exclude these areas from our analysis for transform faults, e.g., the Gadiz and Buyuk Menderes several reasons: the complexity of the boundary fault, grabens in western Turkey south of the North Anato- the influence the Dead Sea Fault Valley marginal lian Fault. normal faults on the eastern blocks, and the lack of The Galilee is divided into two major domains, the structural data from the NE Samaria. Lower and Upper Galilee (Fig. 1). The study area We first provide the geological background of the (which includes the Lower Galilee and the Yizre’el region and describe its main structural and morpho- Valley) consists of a series of E–W trending ridges and logical elements. Then, we analyze the Galilee’s mor- tilted blocks bounded by normal faults (Freund, 1970) pho–tectonic relations by constructing arc-shaped and separated by elongated valleys (Figs. 1 and 2). The sections across the fan-shape extensional domain and study area is bounded in the north by the Upper Galilee its neighboring uplifted blocks. Our analysis results block that rises above the Zurim Escarpment and in the combined with previous observations suggest that the southbytheCarmelblock(Fig. 1). Because the morphologic and tectonic history of the Lower Galilee, northern and southern boundaries are oblique to each the Yizre’el Valley, and their adjacent bounding blocks other (Fig. 1), the extended region has a fan shape. It is are best described by a set of two opposite facing half- about 50 km wide at its eastern side (close to the DSF) grabens, a southern one that started developing as early and narrows towards the west to about 20 km along the as the early Miocene and a northern and younger one coastal plain. that has been developing since the middle Pliocene. The topographic–structural relations in the Galilee The observed relations between the structure and have been studied for almost four decades. The rela- topography are explained by using a semi-quantitative tions between Miocene and Pliocene structures and evolutionary model. topography were studied by analyzing sedimentary sequences (Kafri and Ecker, 1964; Issar and Kafri, 1972; Shaliv, 1991). Fruend (1970), Ron et al. (1984), 2. Geologic background and Ron and Eyal (1985) studied the Neogene tectonic activity and stress fields in the Galilee and pointed out The structure and recent topography did not evolve the correlation between topography and young struc- contemporaneously throughout the Galilee. Its various tural elements. Freund (1965) related the extension in parts experienced different geological histories. A pre- the Galilee to the left lateral displacement and geom- Eocene structure, the Syrian Arc fold belt (Krenkel, etry of the DSF and calculated that such extension 1924; Picard, 1943), which in the Galilee consists of a amounted to 5–7% (Freund, 1970). While Freund’s series of N–S oriented anticlines and synclines, started suggestion that left lateral movement along the DSF developing in the Senonian as a response to closing of explains the extension and some other morphologic the Tethys Ocean (Flexer et al., 1970). The Syrian Arc and structural features in the Galilee, it does not fold belt does not influence the present morphology of provide answers to other observation, mainly the the Galilee. Here we provide a short review of the 226 A. Matmon et al. / Tectonophysics 371 (2003) 223–241 geological history of the region from the late Eocene to of the land left behind a flat exposed plain underlain by the late Pliocene, which is also summarized in Table 1. Eocene carbonate units. This plain drained westward Prior to the late Eocene, the Galilee region was a through a regional drainage system (Picard, 1943, part of a continental shelf that accumulated mainly 1951; Garfunkel and Horovitz, 1966; Nir, 1970; Gar- carbonate sediments. The regression of the Tethys funkel, 1988; Avni, 1990, 1991; Zilberman, 1992; Ocean at the end of the Eocene and the slow uplift Garfunkel and Ben-Avraham, 1996; Begin and Zilber- Table 1 Summary of landscape development in the Galilee Stage Time Dead Sea Fault Valley Carmel Fault line Lower Galilee Zurim Upper Galilee Escarpment 1 Late Eocene to Global sea regression, early Miocene extensive erosion and formation of erosional plain (e.g., Garfunkel, 1988) 2 Early Miocene to Development and fill of middle Miocene local basins. Compatible sedimentation and tectonic rates. Left lateral motion along Initial subsidence Dead Sea Fault (Garfunkel, of Yizre’el Valley 1981). and accumulation of volcanics and sediments. Initial relief. 3 Middle Miocene Tectonic quiescence, some to early Pliocene erosion and deposition in local