Explosive subaqueous eruptions: edifices and deposits

点击翻译按钮获取中文摘要

The four-year research grant entitled "Explosive subaqueous eruptions: edifices and deposits" is a process-oriented study concerning ancient subaqueous eruptions and their volcanoes. The applicable part of the study will use the observed pyroclastic deposit organization to vector possible polymetalic volcanic massive sulfide deposits that are inherent to ancient subaqueous volcanoes. The study areas include the Archean (ca. 2.7 Ga) Blake River Group of the Abitibi greenstone belt, Quebec, the 2.9 Ga Steep Rocks area  Wabigoon Subprovince, Ontario, and the Tertiary Oamaru volcanic complex, South Island, New Zealand. Major emphasis is placed on identifying and characterizing primary subaqueous pyroclastic rocks and differentiating them form their reworked counterparts. The type of eruptions studied are large- to moderate-volume pyroclastic flows and fallout deposits commonly associated with calderas, which are volcanic collapse structures, and small-volume fountaining and Surtseyan eruptions emanating from cinder and pyroclastic cones. The fact that these volcanic edifices occur under water allow us to better understand how subaqueous explosions form and distribute. The principal transport process is that of sediment gravity flows, in which the surrounding medium water plays a prominent role. The three prevalent types of explosive products are pyroclastic flow, fall and surge, with the latter probably not possible in the subaqueous realm. The students will be directly funded from this research project, which consists of one PhD and two MSc-level theses. Students will use basic mapping techniques but also use detailed facies analysis to identify the various rocks suites over a period of 1-3 months per year in the field. The student stipendium and field logistics represent the major costs of this research project.