A revised sedimentological model for the late Oligocene crater lake Enspel (Enspel Formation, Westerwald Mountains, Germany)

Abstract

New longitudinal profiles through the upper Oligocene Enspel Formation have been constructed based on previously published data and unpublished drilling records. The lithofacies is reinterpreted. The Enspel Formation represents deposits of a deep crater lake, Lake Enspel. The crater rim had steep inner slopes that remained intact until the end of deposition. There was no fluvial input. Alluvial inputs (mud flows) were derived from gullies on the crater’s inner rim, with some of these sediments deposited temporarily in alluvial fans. Thin subaerial pyroclastics from nearby volcanic eruptions also accumulated. Crater floor subsidence, episodic heavy rains, and earthquakes triggered flank collapses and slides on the alluvial fan slopes and led to the creation of thick debrites on the lake bottom. These debris flows are partly correlatable over the entire profundal zone. A new sedimentological–limnological cross-section through the Stoffel crater is presented here, and the levels of the lake water and groundwater and the altitudes of the surrounding landscape are given.