Sedimentary and neotectonic history of Lake Ohrid (Macedonia/Albania): acquisition and interpretation of new geophysical and geological data

位于马其顿和阿尔巴尼亚边境的奥赫里德湖是欧洲最古老的湖泊之一，可能是第三纪构造形成的。奥赫里德湖拥有大量的地方性类群，是研究湖泊地质和生物进化之间联系的一流场所。奥赫里德湖已于1993年列入国际发展规划的目标地区，但缺乏适当的现场调查数据。在项目的第一阶段，进行了详细的陆上和海上调查，以揭示奥赫里德湖新近纪的沉积和构造历史，并评估深层钻探的潜力。新的地震数据显示了大量的沉积特征，如阶地、斜地形、块体运动沉积物和广泛的断裂区域，但也显示了一个具有未受干扰沉积物的深层中央盆地。基底顶部沉积物厚度可达近700m。根据声波资料，选择了5个主要钻孔点作为潜在的钻探目标。陆上工作集中于详细的古应力分析，包括形态构造，从而得出了三个独立阶段的初步应力历史。第一阶段的项目成果是2009年1月提交给ICDP的钻探提案“Ohrid湖过去物种形成条件科学合作”（SCOPSCO）的重要组成部分。本次延长方案的计划工作主要是：1)研究奥赫里德湖的沉积历史，反映环境变化；2)对奥赫里德湖及其周围进行详细的构造和断层分析。

Lake Ohrid at the Macedonian/Albanian border is one of the oldest lakes in Europe and was tectonically formed probably during the Tertiary. Lake Ohrid houses large concentrations of endemic taxa and represents a first class site to investigate the link between geological and biological evolution in lakes. Lake Ohrid was included as a target area of ICDP already in 1993 but appropriate site survey data were lacking. In the first phase of the project detailed on- and offshore investigations were carried out in order to reveal the Neogene depositional and tectonic history of Lake Ohrid and to evaluate the potential for deep drilling. The new seismic data show numerous sedimentary features such as terraces, clinoforms, mass movement deposits and areas of extensive faulting, but also a deep central basin with undisturbed sediments. Sediment thickness on top of the basement is up to almost 700m. Based on the acoustic data, five primary sites were chosen as potential drilling targets. The onshore work concentrated on detailed paleostress analyses including morphotectonics, which lead to a preliminary stress history with three individual phases. The results of the first project phase are essential parts of drilling proposal ‘Scientific Collaboration On Past Speciation Conditions in Lake Ohrid (SCOPSCO), which was submitted to ICDP in January 2009. Planned work in this prolongation proposal mainly aims in i) studying the depositional history of Lake Ohrid, reflecting environmental changes, and ii) performing detailed structural and fault analyses of Lake Ohrid and its surrounding.