Firmground ichnofacies recording high-frequency marine flooding events (Langhian transgression, Vallès-Penedès Basin, Spain)

The decapod burrow Spongeliomorpha sudolica occurs associated with transgressive firmgrounds in the transition between Aragonian continental red beds and Langhian marine units in some of the inner sectors of the Vallès-Penedès Basin. This ichnospecies designates branching burrow systems with scratch marks in the walls produced by marine crustacean decapods. The occurrence of Spongeliomorpha represents an example of theGlossifungites ichnofacies. The several horizons where the traces are found are intercalated with continental red beds a few meters below the main transgressive surface, which is overlain by fossiliferous marine sandstones. The Spongeliomorpha-bioturbated layers record short, high frequency marine flooding surfaces that may be related either to actual sea-level changes or to variations in tectonic subsidence or sediment input. In any case, these flooding events punctuated the early phases of the Langhian transgression in the basin

Firmground ichnofacies recording high-frequency marine flooding events (Langhian transgression, Vallés-Penedés Basin, Spain)

The decapod burrow Spongeliomorpha sudolica occurs associated with transgressive firmgrounds in the transition between Aragonian continental red beds and Langhian marine units in some of the inner sectors of the Vallès-Penedès Basin. This ichnospecies designates branching burrow systems with scratch marks in the walls produced by marine crustacean decapods. The occurrence of Spongeliomorpha represents an example of the Glossifungites ichnofacies. The several horizons where the traces are found are intercalated with continental red beds a few meters below the main transgressive surface, which is overlain by fossiliferous marine sandstones. The Spongeliomorpha-bioturbated layers record short, high frequency marine flooding surfaces that may be related either to actual sea-level changes or to variations in tectonic subsidence or sediment input. In any case, these flooding events punctuated the early phases of the Langhian transgression in the basin

The effect of volcanism on cool-water carbonate facies during maximum inundation of Zealandia in the Waitaki–Oamaru region

<div><p>The paleogeography of the Waitaki–Oamaru region during the Oligocene–Miocene maximum inundation was defined by a volcanic paleohigh producing a rimmed cool-water carbonate shelf geometry. Basaltic surtseyan style cones became the setting for a productive cool-water carbonate factory isolated from terrigenous input. To the west, impure wackestones and calcareous siltstones contain terrigenous material derived from low relief landmasses farther to the west. A lowstand following the cessation of volcanism caused the paleohigh to become subaerially exposed, forming an extensive dissolution surface in the east correlative with submarine firmgrounds to the west. Stronger currents from the south and significant storm events sweeping over the high reworked carbonate and glauconitic sediment and deposited it in channels to the north. Carbonate deposition west of the paleohigh filled in the deeper part of the basin eventually resulting in a wider, shallower and more regular shelf environment. Depositional environments of the Waitaki–Oamaru region during the Waitakian (Late Oligocene–Early Miocene) were overall shallower than during the earlier Whaingaroan (Early Oligocene) Stage when a more complex paleotopography existed. This is unlike elsewhere in New Zealand where maximum depth was reached during the Waitakian Stage. Thus, the existence of an isolated, submerged paleohigh in a cool-water carbonate basin can have a significant effect on the evolution of that basin, stimulating carbonate factories to develop where they might otherwise not.</p></div