Sedimentary and tectonic evolution of Lake Ohrid (Macedonia/Albania)
Sedimentary and tectonic evolution of Lake Ohrid (Macedonia/Albania)
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DOI：
10.1111/bre.12063
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发表时间：
2015-02-01
期刊：
影响因子：
3.2
通讯作者：
Schwenk, T.
中科院分区：
文献类型：
--
作者：
Lindhorst, K.;Krastel, S.;Schwenk, T.
奥赫里德湖位于Dinaride-Albanide-Hellenide山脉带内的巴尔干半岛的，是南巴尔干半岛的伸展体制（SBER）内的构造活动地堑。多道地震剖面和测深数据的解释表明，奥赫里德湖形成于两个主要的变形阶段：（1）打开拉分盆地的张扭阶段，以及（2）导致奥赫里德湖目前几何形状的伸展阶段。在最初的开放之后，在晚中新世形成了一个对称的地堑，在拉分型盆地的每一侧以主要的正断层为界。盆地早期几何形态为典型的菱形，受两组主要正断层的制约。厚的原状沉积物是目前在现场的声学基底最深，说明奥赫里德湖是一个潜在的目标，为研究地中海地区的环境变化，钻一个长而连续的沉积物芯。上新世以来的新构造活动沿着大致南北走向的东部和西部主要边界正断层发生，这些正断层部分暴露在现在的湖底。盆地的构造-沉积结构被划分为三个主要的地震单元，覆盖在与河流沉积和湖泊沉积有关的声学基底上。地震相分析揭示了一个突出的周期模式的高，低幅度反射。我们将这种相周期性与周围地区的植被变化相关联，这些变化与冰期/间冰期周期有关。一个明确的相关性是可能回到ca。450千卢比根据上述时期的平均沉积速率外推，得到了约1000年的年龄估计。奥赫里德湖最古老的沉积物为200万年。
Lake Ohrid, located on the Balkan Peninsula within the Dinaride-Albanide-Hellenide mountain belt, is a tectonically active graben within the South Balkan Extensional Regime (SBER). Interpretation of multichannel seismic cross sections and bathymetric data reveals that Lake Ohrid formed during two main phases of deformation: (1) a transtensional phase which opened a pull-apart basin, and (2) an extensional phase which led to the present geometry of Lake Ohrid. After the initial opening, a symmetrical graben formed during the Late Miocene, bounded by major normal faults on each side in a pull-apart type basin. The early-stage geometry of the basin has a typical rhomboidal shape restricted by two sets of major normal faults. Thick undisturbed sediments are present today at the site where the acoustic basement is deepest, illustrating that Lake Ohrid is a potential target for drilling a long and continuous sediment core for studying environmental changes within the Mediterranean region. Neotectonic activity since the Pliocene takes place along the roughly N-S-striking Eastern and Western Major Boundary Normal Faults that are partly exposed at the present lake floor. The tectono-sedimentary structure of the basin is divided into three main seismic units overlying the acoustic basement associated with fluvial deposits and lacustrine sediments. A seismic facies analysis reveals a prominent cyclic pattern of high- and low-amplitude reflectors. We correlate this facies cyclicity with vegetation changes within the surrounding area that are associated with glacial/interglacial cycles. A clear correlation is possible back to ca. 450kyrs. Extrapolation of average sedimentation rates for the above mentioned period results in age estimate of ca. 2Myrs for the oldest sediments in Lake Ohrid.