PETROGRAPHIC AND GEOCHEMICAL COMPARISON OF LIMESTONE AND CARBONATE BRECCIA FROM CALA MADONNA WITH THE CLASSIC TRIASSIC SHALLOWING-UPWARD CYCLES OF THE CAPO RAMA RESERVE (SICILY, ITALY)
These calcitic Cala Madonna deposits differ from those of the previously described mainly dolomitic Capo Rama succession. Although both have been interpreted as cyclic tidal flat deposits, the Cala Madonna limestone examined here is indicative of subtidal carbonate platform interior deposition (i.e., back reef lagoon). Documented petrographic and stable isotope differences between the Cala Madonna subtidal limestone and carbonate breccia suggest that: 1) not all breccia clasts resemble the subtidal deposits from the base of the cycle; 2) breccia clasts are likely derived from subtidal to intertidal deposits from higher up in the cycles; 3) deposits from the basal vs. the upper parts of cycles differ in composition due to shallowing upward and environmental restriction. The origin of Cala Madonna carbonate breccia remains unclear, as it could represent periodic short-term exposure, tectonism (e.g., fault breccia), or platform-wide, longer-term exposure during the Late Triassic that resulted in a regional unconformity and karst formation. Future studies should include continuous sampling within and across multiple sedimentary cycles of both the Capo Rama and Cala Madonna successions to improve the interpretations of their depositional and diagenetic history and regional stratigraphic relationships.