PROMINENT TYPICAL VOLCANIC FORMATIONS AND STURCTURES OF LAVA FLOWS IN HASSA (HATAY) BASALT PLATEAU

HASSA (HATAY) BAZALT PLATOSU’NDA ÖNE ÇIKAN TİPİK VOLKANİK ŞEKİLLER İLE LAV AKINTISI YAPILARI

Abstract

Hassa District is located on the Syrian border of Adana Subregion in the east Mediterranean Region. Located in the northeastern side of Hatay, the province has an area of 577 km2. Hassa located in Amanos Mountains and Antakya-Kahramanmaras graben line has a rugged topography because of the tectonic events. Fault lines exist on both sides of the graben field. While the Fault Line of the Dead Sea is limiting the east part of the graben line, the East Anatolian Fault Line is limiting the west of the graben line. These fracture faults have caused some significant changes in the topography such as shift of the river valleys, rerise of the alluvial cones and formation of weak zones on the earth crust. Particularly, volcanic materials which is formed by the weak zones cover huge areas. The volcanic materials which initially appeared by following the fault lines then turned into the central eruptions. Due to the characteristics such as the radiometric age, morphology, stratigraphic position and alteration colors, and typographical structure of lavas, volcanic areas in Hassa vary depending on their formation time. That lava composed in the most recent period spreads to a large area because of the very low viscosity, amount, discharge rate and emergence place of lava. Therefore, basalt thickness gets thinner and decreases to 40-50 m as we get further away from the pyroclastic cones. The purpose of this study is to introduce the pyroclastic and spatter cones, volcanic shapes that are formed according to the types of solidification, the characteristics of lava tunnels formed in the basalts and lava caves in the Basalt Plateau. For this purpose, the field studies have been reviewed and measurements and assessments were made on necessary locations during field work. The study has been completed by a number of studies in accordance with the aim of the study. Pyroclastic cones that create some interesting landforms in the region are operated as a quarry. Therefore, the cones are faced with the danger of extinction in the near future. In addition, Hassa Organized Industrial Zone and Amanos Tunnels that will be constructed to develop Hassa and its vicinity are in the project stage. Lava tunnels will be damaged in several ways when the project. is implented. Therefore, detailed studies on lava tunnels should be carried out and they should be protected In this study volcanic formations have been investigated under different categories on the basis of their various features. Volcanic formations are classified according to their morphological features, size and location. The volcanic formations are grouped as small puff volcanic formations, small hollowed volcanic formations, micro-topographical volcanic formations and small volcanic formations developing from underlying reliefs. There are “hornitos” with some small relief patterns on the surfaces of lava flows surrounding Haydarlar, Sugediği, Yağmur Border Post, and Yarımaktepe (Photo 4). “Hornitos” are small rootless vents that form on the surface of a lava flow when lava is forced up through an opening in the surface of a flow and then accumulates around the opening. “Pressure ridges” which can be found at anywhere throughout basaltic plateau are one of the small relief patterns which cause surface roughness in the topography (Photo 5). Flowing lava under the surface created a puff of 200-250 meters long and 4-5 meters high on the frozen crust and caused some cracks with 2-3 meter length along the long route. Basaltic blocks of Spatter cones are adherent to the rest because these blocks form from the hot lava with low viscosity. The roundshaped cones with 10-15 m height make the relief rough and undulated (Photo 6). There are three cinder cones, one in Söğüt and two in Yarımakte, in the site under study,. Walnut, hazelnut and chickpea sized lapillis shape the main frame of Yarımaktepe volcanic cones (Photo 7a). Adhering to each other through volcanic cement due to the pressure, Lapillis turn into anglomera (Photo 7f). Volcanic bombs with 20-120 cm height occur in the lapilli zone (Photo 7e). Volcanic ashes and dust in the form of thin layers are the other materials that can be seen in the profiles of volcanic cones. One of the volcanic formations in the basalt plateau is small hollowed volcanic formations. These concave formations appear in two types: The hollow as a result of the flowing of lava under the partly frozen crust and the hollow as result of the collapse of roofs of cave and tunnels. In the formation of the first hollow, however, the lava flows without destroying the crust too much while it spreads. There are also some topographic formations such as arch, bridge, channel, runnel and stone circle in the basalt plateau. The lava flows out of the cracks in the solidified crust in the slope direction and this forms a crust in the exterior surface while the lava continues to flow in the inner side. Lava tunnels and lava caves are one the common small reliefs in the basalt plateau. There are four big lava tunnels from 50 meters to 600 meters long. Named as “Atasoy Lav Tüneli” by the local people (Photo 10), the lava tunnel reaches a height of 6-7 m and a width of 15- 20 m. The roof above the tunnel has a thickness of 3-4 m. The lava tunnel is also 600 meters long. The bottom of the tunnel with its own branches is covered with the basaltic blocks falling from the ceiling. Although it has a very firm structure, there are some collapsed areas in the entrance and basaltic blocks in the bottom, which indicates that the tunnel is affected by the seismic motions of Eastern Anatolia Fault Line. Mal Deliği Lava Tunnel is located in the southwest region of Yarımaktepe Volcanic Cone (Photo 11). Tunnel has two tunnels running vertically, each 100 meters long. The tunnel has a width of 9.2-12.5 m and a height of 4.3-6.7 m. The 30 meter-long part of the tunnel from the entrance towards the northward was collapsed. Therefore, the sizes of the original tunnel’s entr

Özet

Hassa İlçesi, Akdeniz Bölgesi'nin doğusunda yer alan Adana Bölümü'nün kuzeydoğunda yer alan ilçe 577 km2'lik bir alana sahiptir. Amanos Dağları ile Antakya-Kahramanmaraş Graben hattında yer alan Hassa İlçesi, tektonik olayların etkisiyle engebeli bir topografyaya sahiptir. Çöküntü sahanın her iki tarafında fay hatları geçmektedir. Ölü Deniz Fay Kuşağı graben hattın doğusunu sınırlarken, Doğu Anadolu Fay kuşağı ise çöküntü hendeğinin batısını sınırlamaktadır. Bu kırık hatlara bağlı olarak akarsu vadilerinde ötelenme ve birikinti konilerin yeniden yükselmesi şeklinde topografyada belirgin değişikliklere yol açmış olmanın yanı sıra yer kabuğunda da zayıf zonların meydana gelmesine sebep olmuştur. Özellikle zayıf zonları takip ederek çıkan volkanik malzeme çok geniş alanları kaplamıştır. gerekli yerlerde ölçüm ve değerlendirmeler yapılmıştır. Çalışma, amacına uygun olarak bir takım şekillerle desteklenerek tamamlanıştır. Yörede ilginç yer şekillerini oluşturan piroklastik koniler taş ocağı olarak işletilmektedir. Bu nedenle koniler yakın bir gelecekte yok olma tehlikesiyle karşı karşıyadır. Öte yandan Hassa ve çevresinin gelişmesini sağlamak amacıyla yapılması planlanan Hassa Organize Sanayi Bölgesi ve Amanos Tünelleri proje aşamasındadır. Projelerin hayata geçmesiyle lav tünelleri çeşitli şekillerde zarar görecektir. Bu nedenle lav tünelleriyle ile ilgili detaylı çalışmaların yapılarak koruma altına alınması gerekmektedir