Sub-bottom seismic profiler for geoarchaeological and palaeoenvironmental research

NSERC RTI申请资金用于购买Edgetech 3400次底部剖面（SBP）系统。海底剖面仪采用宽带（2-16千赫）、调频“啁啾”声呐脉冲，产生浅水湖泊、泻湖和海洋盆地沉积物地层的详细地震图像。Edgetech 3400系统高度便携（26公斤），可以从小型勘测船（例如Zodiac充气船）上部署，并在浅水环境（< 2米）中产生高分辨率地震记录。在淤泥、泥浆和薄沉积层（< 10厘米）中，地震穿透深度可达50米。新的Edgetech SBP设备迫切需要取代2004年购买的过时的地震剖面系统。新的Edgetech 3400 SBP系统将支持五大湖和地中海地区的多学科地质和地质考古研究。在五大湖，nserc资助的研究将通过测量湖泊沉积物的物理和地球化学特性来更好地了解过去8000年来五大湖下游大风暴事件的频率。在大的风暴事件中，风暴的波浪越过沙滩的屏障，在沿海的泻湖中沉积了独特的上冲沙层。风暴层也因河流的洪水而沉积在湖泊中。这些沉积物（“风暴岩”）可以根据沉积特征（粒度、微动物群、磁性）和地球化学组成从湖床提取的沉积物岩心中识别出来。对风暴事件层花粉的放射性碳定年提供了风暴和极端天气事件的详细时间记录。使用Edgetech 3400对沿海泻湖进行海底地震剖面分析，可以绘制泻湖沉积物和风暴层的厚度和三维排列。高分辨率的湖泊沉积物记录将使麦克马斯特大学的研究人员能够评估过去风暴的频率是否有所不同，以及风暴的变化是否与气候变量有关，例如过去温度和降水的变化。这些数据对于评估风暴频率的预测变化至关重要，并将有助于为面临恶劣天气风险的五大湖人口稠密地区制定应急和基础设施规划。在爱琴海，近岸海岸沉积物的地震剖面可以更好地解决海平面变化、古海岸线位置以及淹没的史前海岸定居点和古港口遗址的潜在位置。海底剖面仪将为麦克马斯特和布洛克大学的8名高素质人员（HQP）提供关键的动手技能和海洋地震调查方法，数据处理和解释的现场经验。这些HQP技能广泛适用于地球科学研究，目前受到私营和公共部门雇主的高度需求。

NSERC RTI funding is requested for purchase of an Edgetech 3400 sub-bottom profiling (SBP) system. The sub-bottom profiler employs broad-band (2-16 kHz), frequency-modulated `chirp' sonar pulses to produce  detailed seismic images of the sediment stratigraphy in shallow lakes, lagoons and marine basins. The highly portable (26 kg) Edgetech 3400 system can be deployed from small survey boats (e.g. Zodiac inflatables) and produces high-resolution seismic records in shallow water environments (< 2 m). Seismic penetration of up to 50 m can be achieved in silt and mud and thin sediment layers (< 10 cm) resolved. The new Edgetech SBP equipment is urgently required to replace an obsolete seismic profiling system purchased in 2004. The new Edgetech 3400 SBP system will support multi-disciplinary geological and geoarchaeological research in the Great Lakes and the Mediterranean. In the Great Lakes, the NSERC-funded research will employ measurements of the physical and geochemical properties of lake sediments to better understand the frequency of large storm events in the lower Great Lakes over the past 8000 years. During large storm events, storm waves over top sandy beach barriers depositing distinctive overwash sand layers in coastal lagoons. Storm layers are also deposited in lakes by the flood discharge of rivers. These deposits ('tempestites') can be identified in sediment cores extracted from the lake bed based on their sedimentary characteristics (grain size, microfauna, magnetic properties) and geochemical composition. Radiocarbon dating of pollen in storm event layers provides a detailed chronological record of storms and extreme weather events. Sub-bottom seismic profiling of coastal lagoons with the Edgetech 3400 will allow mapping of the thickness and 3-dimensional arrangement of lagoon sediments and storm layers. The high-resolution lake sediment record will allow McMaster researchers to assess whether the frequency of storms has been different in the past, and whether variability in storminess is linked to climate variables, such as past changes in temperature and precipitation. These data are critical for evaluating predicted changes in storm frequency and will assist in the development of emergency and infrastructure planning for heavily populated areas of the Great Lakes that are at risk from severe weather.  In the Aegean, seismic profiling of nearshore coastal sediments will better resolve sea level changes, paleoshoreline positions and the potential locations of drowned prehistoric coastal settlements and ancient harbour sites. The sub-bottom profiler will provide 8 high-qualified personnel (HQP's) at McMaster and Brock University with critical hands-on skills and field experience in marine seismic survey methods, data processing and interpretation. These HQP skills are broadly applicable in geosciences research and currently in high demand by private and public sector employers.