Shallow water carbonate platforms (Late Aptian–Early Albian, Southern Apennines) in the context of supraregional to global changes: re-appraisal of palaeoecological events as reflectors of carbonate factory response

Abstract

Abstract. This paper discusses the palaeoenvironmental significance of the "Orbitolina Level", the microbial carbonates and the Salpingoporella dinarica-rich deposits encased in the Aptian/Albian shallow water carbonate platform strata of Monte Tobenna and Monte Faito (Southern Italy). These facies show a peculiar field appearance due to their color and/or fossil content. In the shallow water carbonate strata, the Late Aptian "Orbitolina Level" was formed during a period of decreasing accommodation space. Microbial carbonates occur in different levels in the composite section. They reach their maximum thickness around the sequence boundaries just above the "Orbitolina Level" and close to the AptianAlbian transition, and were not deposited during maximum flooding. S. dinarica-rich deposits occur in the lower part of the Monte Tobenna-Monte Faito composite section, in both restricted and more open lagoonal sediments. S. dinarica has its maximum abundance below the "Orbitolina Level" and disappears 11 m above this layer.On the basis of δ 13 C and δ 18 O values recorded at TobennaFaito, the succession has been correlated to global sea-level changes and to the main volcanic and climatic events during the Aptian. Deterioration of the inner lagoon environmental conditions was related to high trophic levels triggered by volcano-tectonic activity. Microbial carbonates were deposited especially in periods of third-order sea level lowering. In such a scenario, periods of increased precipitation during the Gargasian induced the mobilization of clay during flooding of the exposed platform due to high-frequency sea-level changes, with consequent terrigenous input to the lagoon. This and the high nutrient levels made the conditions unsuitable for the principle carbonate producers, and an opportunistic biota rich in orbitolinids (Mesorbitolina texana and M. parva) populated the platform. In the more open marine domain, the increased nutrient input enhanced the production of organic matter and locally led to the formation of black shales (e.g. the Niveau Fallot in the Vocontian Basin).It is argued that the concomitant low Mg/Ca molar ratio and high concentration of calcium in seawater could have favoured the development of the low-Mg calcite skeleton of the S. dinarica green algae.During third-order sea-level rise, no or minor microbial carbonates formed in the shallowlagoonal settings and S. dinarica disappeared. Carbonate neritic ecosystems were not influenced by the environmental changes inferred to have been induced by the mid-Cretaceous volcanism.The "Orbitolina Level", the microbial carbonates and the Salpingoporella dinarica-rich deposits in the studied Aptian/Albian shallow water carbonate strata are interpreted to be the response to environmental and oceanographic changes in shallow-water and deeper-marine ecosystems.

High‐Resolution C‐Isotope, TOC and Biostratigraphic Records of OAE 1a (Aptian) From an Expanded Hemipelagic Cored Succession, Western Tethys: A New Stratigraphic Reference for Global Correlation and Paleoenvironmental Reconstruction

“…The Ap8–Ap10 segments define a pulsed negative C‐isotope evolution, followed by a stepwise positive trend within segments Ap11 to Ap12 (Figure 2). This C‐isotope excursion is recorded with variable amplitudes in the Mediterranean Tethys (e.g., Piobicco core; Bottini et al., 2015; Vocontian Basin, Herrle et al., 2004; Figure 5; central Italy, Raspini, 2012; Prebetic Platform, Castro et al., 2014; Basque‐Cantabrian basin, Millán et al., 2014), Central Atlantic (Peregrina Canyon, Bralower et al., 1999), and the Pacific (ODP Site 866; Jenkyns, 1995).…”

Opportunistic colonizers in the Kallankurichchi Formation, Cauvery Basin, South India: Implications on Maastrichtian environmental stress

“…Reolid, Sánchez‐Quiñónez, Alegret, and Molina (2015) reported bathymetric changes and resultant oligotrophic‐eutrophic conditions as environmental stress and the influences of stress variably on the r‐strategists (opportunists) and K‐strategists (specialists). Many independent works, including Georgescu (2006), Morrow (2008), Raspini (2012), Ramkumar (2015b) and Phelps et al (2015), documented colonization of opportunists in response to variations in relative sea‐level.…”

Larger benthic and planktonic biostratigraphy and facies of Albian sediments in Coastal Fars Zone (Zagros area, south‐west Iran)

“…The foraminifers were identified by utilizing the published works of several researchers (e.g., Afghah et al, 2020; Afghah & Shaabanpour Haghighi, 2014; Ghanem & Kuss, 2013; Ghanem et al, 2012; Hosseini et al, 2016; Rahiminejad & Hassani, 2016; Schroeder et al, 2010; Simmons et al, 2000; Vincent et al, 2010). Determination of microfacies, (Husinec et al, 2000; Permoli Silva & Verga, 2004) development of a depositional model followed the previous works of Afghah (2016); Mülayim et al (2016); Raspini (2012), and Upadhyay (2014). Classification of the carbonate microfacies was achieved using the schemes of Dunham (1962), Flügel (2004), and Wilson (1975).…”

“…Determination of microfacies, (Husinec et al, 2000;Permoli Silva & Verga, 2004) development of a depositional model followed the previous works of Afghah (2016); Mülayim et al (2016); Raspini (2012), and Upadhyay (2014). Classification of the carbonate microfacies was achieved using the schemes of Dunham (1962), Flügel (2004), and Wilson (1975).…”