The Geology of Beirut - Case Study Example

The geology of Beirut al affiliation Introduction Beirut is the largest in Lebanon as well as its capital. The lies in the coastal realms of the country and has a stunning geological orientation with the coast and the oil fields of Lebanon. The geological orientation of Lebanon has been studied and documented in many oil studies and road building activities in the region for a long time. Given the fact that Lebanon is the Beirut is the largest town in Lebanon and is the economic mainstay of the region, a lot of land-building processes have been taking place in and around the place. Their earth building processes expose a lot of geological information of the place suitable for extensive studies and exploration by geologists. Past records of the geologic information of Beirut indicate that the rock structure and strata in the region have been changing over time due to the changes taking place in the region and even beyond. Such changes include the occurrences of earthquakes, volcanic eruptions, and other related earth movement processes. These processes, as Gradstein & Ogg (1996) notes lead to a lot of changes occurring over the surface of the earth. As Flexer, Honigstein, Rosenfeld, & Polishook (1990) notes, earth movement processes mainly affect the surface and sub-surface rocks but have very little effects on the rock lying deeper under the earth’s surface. The evidence of such changes and effects has been noted in the quarry mines and other geological processes taking place in and around the Beirut region. This paper discusses the geological orientation and composition of Beirut from the pre-historic times to the present date. The changes that have occurred in the geological composition of the region have been traced and documented. Detailed illustration of the effects of various natural and human-induced processes such as volcanicity, earthquakes and earth building processes including road building, earth blasting which have been responsible for the geology of the region have been documented for further reference too. The geology of Beirut This section discusses various geological components of the lands in and around Beirut. The various processes and activities that have resulted in the changes that have occurred in the geological characterization of the lands of Beirut have been detailed and documented for further clarification. The carbonate stratigraphy of the Jurassic-Cretaceous period The Beiruts land mass is mainly an expansive oil field characterized by a great variety of oil rocks. Much of the crustal segments are made up of the carbonate platforms that were deposited on the northwestern regions of the Arabian plate. A lot of geologic works going on in the region and characterization of the geological processes here have been extensively conducted in the coastal regions where a lot of activities are taking place. The coastal landforms and coast building processes have had great and extensive influence on the geologic formations of the region from the historic past (Hirsch & Picard, 1988). A lot of such stratigraphic sequences of carbonic origins are exposed in the regions surrounding the coastal lands of the Beirut landmass. A lot of the canyons found around the place expose their geologic characteristics of carbonic origins and characterization. The oldest units of these carbonic rocks structures of the Jurassic period are evident in the lower northeastern coasts of Beirut regions. The upper Cretaceous compositions are found along the western sides of the region characterized by the Chekka formations. Different types of carbonaceous rocks characterize these formations depending on their locations and historical characteristics. Among the most common formations recognized in various excavations is the micritic limestone, dolostones, chalk, pelmicrite, marl, etc. other formations dominating the regions geology are a combined manifestation of the above mentioned rock formations. The combinations range from coarse grains to the fine-grained characteristics thus bringing a thin difference in the geologic differences around the regions. Various geochemical researches have been conducted to determine the chemical composition of the various rock characteristics found in the region. Picard & Hfrsch (1987) for instance carried out and extensive geochemical research along the coastal shows of the city of Beirut neighboring the Mediterranean sea and came up with findings that have been used in various geologic characterization of the regions around the Beirut region. According to the findings of Picard & Hfrsch (1987), the micritic limestone of the lower northeastern coasts of Beirut is mainly constituted of chemical/minerals such as calcium, aluminum, iron, tin, potassium and other minerals in rare findings. Other mineral composition of these rocks includes the Rb, Ga, Nb, U, Th, and REE minerals. These minerals are found in their rare forms in various limestone rocks littering the lower northeastern coasts of Beirut. Most geologists have associated the constituents of these rocks to the various formations that have occurred along the seas of Beirut including the great Lebanese earthquake of 9th July A.D. 551. The chalks found in the Chekka region is mainly characterized by a high phosphorous content that increases over time and scale following the various changes that are occurring in the region and the neighboring regions. Regions are highly connected and what happens in one region bear a significant impact on what goes on in the neighboring regions. This is due to the interconnectedness in crustal rocks and formation of time and space augmented by various events. Various researches have shown that certain earth movement processes such as earthquakes and volcanic eruptions that have taken place in the region over the past years (Gradstein & Ogg, 1996). For instance, the amount of Nickel, Tin and Nb components found in some rock formations in the region are linked to the Mesozoic earthquakes that occurred in some parts of the Beirut and central Lebanon which led to massive rocks transformations. Various diagrammatic representations drawn by various geologic surveys of the regions of Beirut explain the ancient and recent formations associated mainly with the Mesozoic carbonations augmented by volcanicity and tsunamigenic forces of the A.D. 551 which resulted from the mass earthquake of Beirut and Tripoli. Diagram 1 shows the extent of spread of the A.D. 551 Beirut-Tripoli earthquakes and its impacts on the sea bordering regions and their rock compositions. Diagram 1: Geologic mapping of the A.D.551 Beirut-Tripoli Earthquake The red lines show the quake paths and the rock formations that occurred along the paths. The red box show the Lebanese band that was formed as a result of the extensive quake formations and the small red circles representing the coastal cities that were affected by the quake deformation along the coastal lines of Lebanon including the city of Beirut. The middle Cretaceous classification of Beirut geology The middle Cretaceous classification of the geologic formations of the Beirut region focuses on the classification of various rocks formations that occurred during the middle Cretaceous period and are characterized by various factors such as changes in sea composition, quake formations and the volcanic forces that occurred in the region during these times. The middle Cretaceous geologic mapping of the region addresses various fallacies that are evident across Lebanon and particularly in the coastal regions and cities including the city of Beirut. These classifications indicate various major changes that occurred north-south of the region or east-west the region, especially along the coastal regions. The sea floor spreading is one factor that has resulted in extreme geologic changes occurring in the region during the Cretaceous periods and has continued to influence the regions geology over time and scale (Flexer, Honigstein, Rosenfeld, & Polishook, 1990). For instance,, geologists have noticed major alterations in the lower Cretaceous sections of the coastal Beirut region thus leading to the modification of the shale, sandstones and the limestone that characterize the shallow waters formed in the East Coasts of the region. The northward alterations are evident mainly on the limestone sequences that are prominently blended with the carbonate grainstones as well as packstones. East-west changes have also been noted in the region since the onset of the major geologic occurrences in the area. Conclusion The geology of Beirut has not been constant for a long time just as any other region’s geologic orientations around the globe. Various factors have influenced rock formations in the regions of Beirut and beyond. Both localized and large-scale geologic factors are responsible for various rocks formations in the region. Significantly, the volcanic and earthquakes have been noted to be the most influencing factors that have affected the geologic formations in the regions of Beirut over time and scale. Most of the Beirut’s rock formations are of the carbonaceous origin influenced by various factors including seafloor spreading and natural earth movement processes. References Flexer, A., Honigstein, A., Rosenfeld, A., & Polishook, B. (1990). Geology and Geotechnical properties and exploitation of chalk in Israel: an Overview. In T. Thomas, Chalk (pp. 63-70). London. Gradstein, F. M., & Ogg, J. (1996). A Phanerozoic time scale. Episodes, 3-4. Hirsch, F., & Picard, L. (1988). The Jurassic facies in the Levant. Journal of Petroleum Geology, 11, 277-308. Picard, L., & Hfrsch, F. (1987). The Jurassic stratigraphy in Israel and the adjacent countries. Isr. Acad. Sci.Jerusalem, 1407. Read More