הגיאולוגיה של הכרמל מחזורים ×•×•×œ×§× ×• - Geological Survey of Israel - המכון ...

Formation consists of bedded dolomites, and in southern Carmel it displays a facies changeinto the undivided Bina Formation. The described stratigraphic relationship between the twoformations is different from the common one in northern Israel (where the Bina Formationoverlies the Sakhnin Formation). It is consistent, however, with the observations concerningthe occurrences of limestone facies in the Sakhnin Formation, and dolomitic facies in the BinaFormation. The fourth cycle, like the two preceding ones, started with rapid subsidencethroughout most of the Carmel. It was different, however, by the establishment of reef (andbioclastic products) environments, rather than the planktonic environments that characterizedthe beginnings of the previous cycles.The great variety of features that is displayed in the different cycles can be related to anumber of controlling factors and their mutual interactions.1. Bathymetry. The carbonate platform in the Carmel area was rather flat and uniform duringdeposition of the first cycle (Albian). During the Cenomanian-Turonian two subenvironmentswere recognized, the one restricted and relatively shallow, the other openand deeper (65-80 m). Local slopes were established between the two sub-environments,but otherwise there is no evidence of a directional and uniform slope. The edge of theplatform, whether rimmed or non-rimmed, was well defined, and beyond it started thesteep slope towards the Tethys Ocean.2. Rudist reefs. Rudist reefs occurred as either barrier or isolated forms. The barrier reefswere located along the edge of the platform exclusively, even though at certain times somestretches of the platform’s edge were not colonized by reefs. One effect of the barrier reefswas the restriction of water exchange between the open sea and the platform, whichresulted in elevated salinity. The abundant dolomites in association with the barrier reefsare ascribed to these effects. The non-rimmed parts of the platform contain mostly chalksand limestones, which reflect normal salinity and improved water circulation. Isolatedreefs are recognized both on the platform and the platform’s edge. They had a key roleduring accumulation of the Muhraqa Member (Bina Formation), in affecting bathymetry,sediment type, and water circulation in their proximity.3. Volcanic activity. The majority of volcanic eruptions in Mount Carmel were explosive,with only a few effusive ones. It took place in four separate phases from the Latest Albian(99 Myr) to the Late Cenomanian (95.4 Myr), and a single Senonian event (82 Myr). Threeof these phases (V 1 , V 2 , V 4 ) were active at the beginnings of cycles 2, 3, and 4respectively, and one (V 3 ) in the middle of the Zikhron Formation (third cycle). Thepyroclastic volcanoes formed relatively small cones, which protruded out of the sea duringIII