Famennian brachiopod and gastropod occurrences on top of Devonian seamounts, Elbingerode and Iberg Reefs, Harz Mts., Germany

Abstract

Famennian brachiopods and gastropods occur locally on top of the Elbingerode and Iberg Reefs (Harz Mts.). The Elbingerode occurrence is found in a small depression of the former reef surface and belongs to thePalmatolepis triangularis conodont-zone. It is a brachiopod-gastropod packstone, which also contains limited numbers of crinoids, solitary corals, and trilobites. The Iberg occurrence is a crinoid grainstone, which contains few brachiopods and solitary corals. The grainstone is found in two neptunian dikes cutting the reef, and belongs to thePalmatolepis marginifera conodont-zone. Five brachiopod and five gastropod taxa are described, with the new speciesHolopea ruchholzi. Stable isotopes (δ13C, δ18O) of cement and matrix of Famennian limestones suggest no relation to a methane seep, as described for the different, late Visean brachiopod limestone on top of the Iberg Reef.