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The late Miocene is a crucial interval for global climate evolution as well as for the regional geodynamic evolution of the Central Mediterranean area. It spans the transition from the warm Mid Miocene Climatic Optimum, associated with the major Monterey Carbon Isotope Excursion, to the cooler Pliocene, characterized by a bipolar glaciation. Within this climatic transition, during the early Tortonian, a positive carbon isotope excursion related to a global carbon cycle perturbation is recorded, named Carbon Maximum 7 (CM7). In this study, two upper Serravallian–lower Tortonian carbonate ramps of the Central Mediterranean have been analysed: the Latium‐Abruzzi and the Apula ramps (Central Apennines, Central Italy). Carbon isotope ratios have been coupled with facies and microfacies analyses with the aims: (1) to identify the CM7 in the Central Mediterranean carbonate ramp successions; (2) to evaluate potential carbonate factory changes or demises related to the CM7; and (3) to discriminate the role of global vs regional factors in affecting the Mediterranean carbonate ramps. The two studied ramps show different evolutions due to regional geodynamics causes. The Latium‐Abruzzi ramp drowns in the Tortonian, while the Apula shows a regressive trend, with upper Tortonian middle ramp facies overlying the lower Tortonian outer ramp. Despite the complex geodynamic setting, a positive carbon isotope shift has been identified in both ramps and correlated with the CM7. This positive carbon isotope shift may be linked to the strengthening of the global ocean circulation during the late Miocene cooling. This strengthening of the circulation enhanced the coastal upwelling, bringing nutrient‐rich waters to the surface and triggering an enhanced primary productivity consistent with the CM7. [ABSTRACT FROM AUTHOR]

Detailed study on the Lower Ordovician Mungok Formation in the mideastern part of the Korean peninsula has led to recognition of seven lithofacies which can be grouped into seven facies associations (FAs): FA1 ( lagoon), FA2 ( shoal), FA3 ( shoreface), FA4 ( inner to mid-ramp), FA5 ( inner to outer ramp), FA6 ( mid- to outer ramp), and FA7 ( outer ramp). Spatio-temporal organization of the FAs represents homoclinal ramp environments with fringing ooidpeloid shoals. Correlation and lateral thickness variation of the FAs suggest that deep part of the basin might have been located toward the northern part of the study area. The relative sea-level curve inferred from the facies analysis suggests that the Mungok Formation evolved through three depositional stages in accordance with 3rd-order sealevel change. The organization of the facies succession indicates that the inner ramp facies associations (FA1 to 3) of the Mungok Formation are characterized by non-cyclic facies succession whereas the midand outer ramp facies associations (FA 4 to 7) have distinct cyclicity except non-cyclic FA 7. The difference in the facies successions between the inner ramp and the mid- to outer ramp area may result from the various depositional regime across a ramp. A non-cyclic facies successions of inner ramp facies (e.g., packstone to grainstone and lime mudstone) are suggestive of mosaic-type distribution that is controlled mostly by wave, storms, tides, currents, and local geomorphology. In contrast, cyclic facies successions (e.g., pebbly limestone conglomerate, limestone-shale alternation, and calcareous shale) represent a simple belt-type distribution of mid- to outer ramp facies that seems to reflect shifts of facies belt caused by sea-level changes. The partitioning of inner and mid- to outer ramp facies is appropriate for understanding the facies development of the Mungok Formation and similar ramp successions with distinct inner and mid- to outer ramp facies. [ABSTRACT FROM AUTHOR]

Abstract: The Neoproterozoic Wynniatt Formation, part of the upper Shaler Supergroup, is exposed in the Minto Inlier of Victoria Island, Canada, and was deposited in the intracratonic Amundsen Basin. The unit consists of a southwest-thickening (480 to 1000m over ~300km) shallowing-upward succession of three carbonate ramp sequences separated by regional unconformities. In ascending order: 1) inner to outer ramp carbonate facies, gradationally overlain by siliciclastic rocks of a pro-delta slope setting; 2) inner to mid-ramp subtidal carbonate facies, including a regional stromatolitic barrier system; and 3) outer ramp carbonate (gravity flow) facies overlain by shallowing-upward subtidal to intertidal, mixed siliciclastic-carbonate inner ramp facies. Spatial arrangements of nineteen lithofacies illustrates that each carbonate ramp sequence represents part of a distally steepened, storm-dominated carbonate ramp, with an interval of deep-water carbonate rocks coincident with oceanic restriction that elevated salinity. Migration of depocentre loci for successive ramp stages reflects changing patterns of subsidence. This may identify far-field extensional effects in this intracratonic basin because ages of the lower (~850Ma) and middle (~761Ma) formation bracket initiation of supercontinent (Rodinia) break-up. Our work offers an improved sedimentary framework for interbasinal correlation with coeval Neoproterozoic basins. It highlights temporal changes in carbonate facies compared to older carbonate successions in the Shaler Supergroup, and it defines depositional context for the Tawuia-Chuaria assemblage zone, providing important interbasinal biostratigraphic correlation. [Copyright &y& Elsevier]

Abstract: High-diversity marine biotic communities characterize the lower Kasimovian (Upper Pennsylvanian) carbonates of the Las Llacerias Formation in the Ándara Massif (Picos de Europa Province, Cantabrian Mountains, Spain). The carbonates accumulated on a small thrust-top ramp system. Within the shallow, low-energy and euphotic realms, biotic communities were characterized by abundant photozoans (calcareous algae and cyanobacteria) and heterozoans including filter and suspension feeders (calcareous and siliceous sponges, bryozoans, brachiopods, crinoids), diverse other metazoans (rugose solitary and colonial corals, tabulate corals, bivalves, gastropods and echinoids), benthic foraminifers including very abundant small incrusting “tubiforms” and conspicuous swarms of cement-filled spheres (calcispheres or Penella). Small-sized buildups of chaetetid sponges, syringoporids, branching rugose corals, Anthracoporella and phylloid algae commonly developed in these shallow-water environments. Meanwhile, mud mounds formed at greater water depths, mostly below the lower limit of the phothic zone. The occurrence of such diverse biotic communities and the grain composition of the shallow-water deposits, not recorded in the platform-top successions of the antecedent Bashkirian–Moscovian carbonate shelf (Valdeteja and Picos de Europa formations) are interpreted as linked to increased nutrient levels (mesotrophic to mildly eutrophic conditions) in the actual sea-surface water. The nutrients are inferred to have resulted from land-derived fluxes from the rivers draining the adjacent growing Variscan Orogenic chain. Nutrients were subsequently transported into the narrowed marine shallowing foreland basin located in the eastern side of Pangea, within the palaeoequatorial humid belt. Comparison to the Pennsylvanian Auernig Group in the Carnic Alps allows the discrimination between the influence of land-derived versus upwelling-derived nutrients, providing a useful tool in the interpretation of biotic assemblages in the fossil rock record. [Copyright &y& Elsevier]

The Peerless Park Member [Keokuk Limestone, Lower Carboniferous (Visean, Mississippian)], exposed in the St. Louis, MO, area includes a carbonate-filled channel complex with lithology and faunal elements distinct from under- and overlying strata. The complex is confined within a channel of 100-m apparent width that is under- and overlain by cherty, glauconitic crinoid–bryozoan–skeletal wackestone, packstone and grainstone with abundant hardgrounds and little evidence for wave or current energy. Laterally, the valley includes two subchannels separated by a subtle high. The deeper subchannel truncates up to 5 m of strata.The maximum thickness of the channel fill and associated deposits is 6 m. The channel fill includes a matrix-supported conglomerate locally at its base, non-cherty quartz silty–foraminifer–peloid–crinoid–bryozoan–skeletal grainstone with spectacular lateral accretion foresets up to 5 m thick, and cherty skeletal packstone. A capping foraminifer–skeletal grainstone is erosionally overlain by a 10-cm thick quartz siltstone that grades up into glauconitic crinoid–bryozoan–skeletal wackestone and packstone.On the channel flanks, correlative strata of the Peerless Park Member are less than 1 m thick, and include a lower non-cherty crinoid–foraminiferal–skeletal grainstone, a middle cherty packstone and an upper skeletal grainstone. The upper grainstone is in turn erosionally overlain by the thin quartz siltstone that abruptly grades into the crinoid–bryozoan–skeletal wackestone and packstone of the upper part of the Keokuk Limestone.The strata of the Peerless Park Member are interpreted to be the result of a relative fall of sea level that places shallow water, high-energy inner ramp grainstone immediately above deeper water, outer ramp packstone and grainstone. There is no evidence for gradual downward or basinward migration of facies belts. Instead, shallow water facies appear to have abruptly jumped downdip. Likewise, no field or petrographic evidence for subaerial exposure has been recognized, so the relative fall in sea level may not have subaerially exposed the area. This occurrence of an isolated, downdip carbonate grainstone filled channel complex not accompanied by progradational, forced regressive deposits appears to be unique in carbonate ramp depositional systems and the channel includes fill with character different from many previously documented ramp carbonate-filled channels. [Copyright &y& Elsevier]