Marine carbonate member
Marine carbonate member
Early Triassic, Permian, and Pennsylvanian
Medium- to coarse-grained marble derived from limestone and dolomite. Most of the mapped bodies are in the central Sierra with one outlier north of Lake Kaweah. The large marble bodies shown on the map generally lack known preserved fossils. However, the largest body, near Columbia, is reported to have Late Devonian fossils (Haughy and others, 2024). Schweickert and others (1977) report “Permo-Carboniferous” horn corals from an olistolith near the Tuolumne River. In contrast, a marble layer too small to show at the scale of this map in the northern part of the Calaveras Complex includes Permian to Pennsylvanian conodonts (Hietanen, 1981), and in the south-central part of the complex, another layer of marble too small to show includes Early Triassic conodonts (Bateman and others, 1985). In both cases, the geometry of the marble body strongly suggests that it is not an olistolith. The association of this unit with mafic volcanics near the Stanislaus River, including the Devonian body near Columbia, led Schweickert and others (1977) to suggest this unit there is made of a large fragment of basaltic seamount accreted to the continental margin. We differ from the formally accepted age for this unit based on younger fossils found within its accepted extent (Bateman and others, 1985).