Pre-site survey for potential new ICDP sites in southern Patagonia (Argentina)

我们提议对计划中的ICDP取心地点(计划用于GLAD200系统)进行气枪地震勘测，该地点位于1至2 Ma的老马尔拉古纳Potrok Aike，并对位于阿根廷巴塔哥尼亚南部的梅塞塔-塞罗-科罗拉多火山区迄今尚未研究的火山口湖泊进行现场前勘测。在拉古纳波特罗克艾克之前和正在进行的研究表明，一个漫长的、不受干扰的沉积物记录可能跨越几个冰川/间冰期周期，到目前为止，南半球中纬度的冰川/间冰期尚未确定。根据3.5千赫的地震调查，发现了厚度超过30-40米的水平分层的远洋沉积体。对长达17米的沉积物进行短取心和活塞式取心，提供了关于全新世水分平衡变化的数据-这对目前依赖水的绵羊养殖经济具有重要价值。最大沉积物厚度最终是提议新的ICDP钻探场地所需要的，并将通过气枪地震来实现。为了优化财政资源的使用，我们还将利用这次实地考察，对科罗拉多州梅塞塔的水深测量、物理和化学湖沼学、现代花粉和硅藻以及表层沉积物进行前期调查，以可能提出第二个适合作为ICDP取心地点的湖泊，从而形成一条南北横断面。

We propose to carry out an airgun seismic survey for the planned ICDP coring site (scheduled for the GLAD200 system) at the 1 to 2 Ma old maar Laguna Potrok Aike and a pre-site survey of so far unstudied crater lakes in the volcanic area of the Meseta Cerro Colorado, both in southern Patagonia (Argentina). Previous and ongoing investigations at Laguna Potrok Aike promise a long and undisturbed sediment record that might span several glacial/interglacial cycles unidentified for midlatitudes of the southern hemisphere until now. Based on a 3.5 kHz seismic survey a horizontally layered body of pelagic sediments with a thickness exceeding 30-40 m was recognized. Short and piston coring of up to 17m of sediment provide data about Holocene variabilities of the moisture balance - data which is of great value for the prevailing water-dependent sheep farming economy. The maximum sediment thickness is ultimately needed for proposing a new ICDP drilling site and will be achieved by airgun seismic. To optimize the use of financial resources we will use this field trip also for a pre-site survey for bathymetry, physical and chemical limnology, modern pollen and diatoms and surface sediments in the Meseta Cerro Colorado to perhaps come up with a second lake suitable as ICDP coring site thus generating a north-south transect.