Sedimentology on profile Co1202 from Lake Ohrid

Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study climatic and environmental changes during the last glacial-interglacial cycle are reconstructed using lithological, sedimentological, geochemical and physical proxy analysis of a 15-m-long sediment succession from Lake Ohrid. A chronological framework is derived from tephrochronology and radiocarbon dating, which yields a basal age of ca. 136 ka. The succession is not continuous, however, with a hiatus between ca. 97.6 and 81.7 ka. Sediment accumulation in course of the last climatic cycle is controlled by the complex interaction of a variety of climate-controlled parameters and their impact on catchment dynamics, limnology, and hydrology of the lake. Warm interglacial and cold glacial climate conditions can be clearly distinguished from organic matter, calcite, clastic detritus and lithostratigraphic data. During interglacial periods, short-term fluctuations are recorded by abrupt variations in organic matter and calcite content, indicating climatically-induced changes in lake productivity and hydrology. During glacial periods, high variability in the contents of coarse silt to fine sand sized clastic matter is probably a function of climatically-induced changes in catchment dynamics and wind activity. In some instances tephra layers provide potential stratigraphic markers for short-lived climate perturbations. Given their widespread distribution in sites across the region, tephra analysis has the potential to provide insight into variation in the impact of climate and environmental change across the Mediterranean.奥赫里德湖（Lake Ohrid）可能形成于上新世，是欧洲现存最古老的湖泊。本研究以奥赫里德湖一处15米长的沉积序列为研究对象，通过岩性学（lithology）、沉积学（sedimentology）、地球化学（geochemistry）与物理代用指标分析（physical proxy analysis），重建了末次冰期-间冰期旋回期间的气候与环境变化历史。研究依托火山灰年代学（tephrochronology）与放射性碳定年法（radiocarbon dating）建立了年代框架，其底部年代约为136 ka。不过该沉积序列并不连续，在约97.6 ka至81.7 ka之间存在沉积间断（hiatus）。末次气候旋回期间的沉积物堆积过程，受多种气候调控参数的复杂相互作用，以及这些参数对流域动力学（catchment dynamics）、湖沼学（limnology）与湖泊水文过程的影响共同制约。通过有机质、方解石、碎屑岩屑（clastic detritus）与岩石地层学（lithostratigraphy）数据，可以清晰区分温暖的间冰期与寒冷的冰期气候环境。在间冰期阶段，有机质与方解石含量的突变记录了短期气候波动，反映了气候驱动的湖泊生产力与水文条件变化。冰期阶段，粗粉砂至细砂级碎屑物质含量的显著波动，可能是气候驱动的流域动力学与风力活动变化的直观体现。在部分层位中，火山灰层（tephra layers）可作为短期气候扰动（climate perturbations）的潜在地层标志（stratigraphic markers）。鉴于火山灰在该区域多个遗址中广泛分布，火山灰分析有助于深入解析地中海地区气候与环境变化影响的空间异质性。