High-resolution chronostratigraphy of palaeoecologic and isotopic changes in shallow-marine carbonates: Deciphering the completeness of the Aptian record in the Apennine carbonate platform (southern Italy)

Graziano, Roberto; Raspini, Arturo

doi:10.1016/j.cretres.2017.12.008

Cited by 13 publications

(12 citation statements)

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“…These short-lived episodes lasting ca 1 Ma (Li et al, 2008) are characterized by sediments with an unusually high content of organic carbon and distinct positive and negative shifts in the stable carbon isotope (δ 13 C) record of marine sediments on a global scale (Scholle and Arthur, 1980;Menegatti et al, 1998;Leckie et al, 2002;Herrle et al, 2004). The effects of these pertubations on the global carbon reservoir are expressed by synchronous isotopic shifts which manifest in marine carbonates (δ 13 C carb ; Menegatti et al, 1998;Bellanca et al, 2002;Herrle et al, 2004;Heldt et al, 2008;Godet et al, 2014;Graziano and Raspini, 2018) and organic matter (OM) (δ 13 C org ) from both marine (Menegatti et al, 1998;Dumitrescu and Brassell, 2006;Millán et al, 2009;Gaona-Narvaez et al, 2013a;Sanchez-Hernandez and Maurrasse, 2016) and terrestrial sources (Gröcke et al, 1999;Ando et al, 2002). Thus, the consistency and reproducibility of the carbon isotope shifts in widely distributed locations during OAE 1a provide a robust chronostratigraphic tool for stratigraphic correlation (Scholle and Arthur, 1980;Weissert and Bréhéret, 1991;Menegatti et al, 1998;Herrle et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Regional palaeoenvironmental influence on organic matter sequestration and characteristics of carbon isotope segment C5 in a hemipelagic sequence, Organyà Basin, northeast Spain

Socorro

Maurrasse

2020

The Depositional Record

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The Cretaceous marine sedimentary record is punctuated by episodes of unusually high rates of organic carbon burial termed oceanic anoxic events. The El Pujal Section archives the response to perturbations of the global carbon cycle associated with Oceanic Anoxic Event 1a in a hemipelagic setting of the Organyà Basin. Here, the aim is to understand the lithological and geochemical responses to changing palaeoenviromental conditions associated with carbon isotope segment C5 of Oceanic Anoxic Event 1a. A multi‐proxy approach is applied to characterize how regional factors influenced the accumulation of organic‐rich sediments during this period of severe oceanic oxygen deficiency. Source specific biomarkers demonstrate that the bulk organic matter derives from in‐situ production, with lesser inputs from allochthonous sources. High‐resolution stable carbon isotope data (δ13Corg) were used to establish the refined details of segment C5. Pulses of fluvial fluxes associated with climate fluctuations supplied variable quantities of terrestrial organic matter with more negative isotopic values, which left their intrinsic signature superimposed on the global δ13Corg signal of segment C5 as minor negative spikes. Primary production sustained by fluvial inputs of biolimiting elements provided abundant labile organic matter conducive to oxygen‐deprived conditions as attested by concomitant peaks in total organic carbon, relatively lower benthic faunal counts, lower bioturbation index, higher concentration of pyrite and enrichments in redox sensitive trace elements. However, organic matter preservation was not chiefly controlled by redox conditions as physical encapsulation by clay minerals probably played a significant role. In addition, coincident inputs of terrestrial organic matter with more inert properties and prone to be bound to clay minerals supplemented the accumulation of organic matter, especially during intervals of enhanced terrigenous fluxes. The combined results underscore how despite sharing common global forcing factors, regional palaeoenvironmental conditions are more important in determining the sedimentary expression of Oceanic Anoxic Event 1a.

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Section: Introductionmentioning

confidence: 99%

Regional palaeoenvironmental influence on organic matter sequestration and characteristics of carbon isotope segment C5 in a hemipelagic sequence, Organyà Basin, northeast Spain

Socorro

Maurrasse

2020

The Depositional Record

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“…The stable carbon isotope (δ 13 C org and δ 13 C carb ) record of the Early Aptian is well established and has been extensively documented at sites worldwide, as the results demonstrate global synchroneity in the variations that reflect times of extensive perturbations in the global carbon cycle (Arthur et al, 1985; De Gea et al, 2003; Godet et al, 2006; Graziano & Raspini, 2018; Herrle et al, 2004; Hu et al, 2012; Jenkyns, 1995; Kuhnt et al, 1998; Leckie et al, 2002; Marsaglia, 2004; Menegatti et al, 1998; Michalík et al, 2008; Núñez‐Useche et al, 2015; Popp et al, 1997; Saito & Ando, 2000; Sanchez‐Hernandez & Maurrasse, 2016; Scholle & Arthur, 1980; Tejada et al, 2009; van Breugel et al, 2007; Yilmaz et al, 2004). Hence, chemostratigraphic correlations of coeval sections using stable carbon isotopes have become a widely used proxy for determining the chronology of Early Cretaceous deposits based on the initial eight carbon isotope segments C1 (latest Barremian) to C8 (late Aptian) of the δ 13 C curves (carbonate and organic) at Rotter Sattel, Switzerland, and Cismon, Italy (Menegatti et al, 1998).…”

Section: Discussionmentioning

confidence: 92%

Chemostratigraphic characteristics of trace elements, biomarkers and clay mineralogy indicating environmental conditions within Aptian sediments of the Organyà Basin, North‐east Spain, prior to the onset of OAE 1a

Herdocia

Maurrasse

2022

The Depositional Record

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Shifting palaeoceanographic and palaeoclimatic conditions together with fluctuating eustatic sea levels during the Early Cretaceous Aptian stage led to a globally widespread deposition of organic-rich marine sediments designated Oceanic Anoxic Event 1a. Here a detailed lithostratigraphic and geochemical study is presented for 35.6 m of the Cabó Formation, part of the Organyà Basin, North-east Spain, to assess intermittent periods of enhanced organic carbon preservation in Lower Aptian sediments preceding Oceanic Anoxic Event 1a. The Organyà area contains well-exposed outcrops of Mesozoic black to dark grey marlstones and limestones with variable amount of organic matter (OM) indicative of oxygendeficient conditions. Previous work in a section near the town of Organyà focussed on lithostratigraphy and biostratigraphy and assigned a Barremian-Aptian age. This study aims to provide an updated age based on carbon isotope correlation established elsewhere, and assess the chemostratigraphic characteristics of the Barremian-Aptian to clarify environmental changes regarding oxygen deficient conditions in the basin at that time. The δ 13 C org values fluctuate from −22.1 to −24.4‰ showing concurrence with results at the El Pui section west of the studied section. Chemostratigraphic correlation of the δ 13 C org reveals that the section is within segment C2, in the Lower Aptian. Redox-sensitive trace elements (V, Ni, Co, Cr, Cu, Mo) indicate heightened dysoxic conditions at five organic-rich layers, here designated carbonaceous layers (TOC >2%), associated with enhanced terrigenous fluxes coincident with increased major elements (Al, Si and Ti) during these intervals. Biomarkers from six levels showed n-alkane distributions with chain lengths from nC 14 to nC 34 , mostly below nC 21 indicating a predominance of marine-derived OM. Climate conditions inferred from variable smectite, and kaolinite content suggests fluctuating humid-warm conditions. The results thus reveal that the Organyà Basin experienced intervals of distinct oxygen-poor conditions prior to the onset of Oceanic Anoxic Event 1a. How to cite this article: Herdocia C. & Maurrasse FJ-M.R. (2022) Chemostratigraphic characteristics of trace elements, biomarkers and clay mineralogy indicating environmental conditions within Aptian sediments of the Organyà Basin, North-east Spain, prior to the onset of OAE 1a.

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“…Most worldwide Chondrodonta accumulations can be correlated to a short interval preceding the onset of OAE1a (Fig. 12); in some cases, the accumulations extend also within the anoxic event and even slightly above (for example, Apennine Platform; Graziano & Raspini, 2018), whereas in other areas they have not been reported (for example, Adriatic Platform; Huck et al ., 2010). These observations suggest that the proliferation of Chondrodonta , mainly triggered by increased nutrient availability, would have been favoured or prevented by other local and/or regional environmental fluctuations during the early Aptian.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

“…During the early Aptian, Chondrodonta beds are reported in several shallow‐water carbonate platforms bordering the Tethys Ocean (e.g. Masse, 1993; Császár et al ., 1994; Malchus et al ., 1995; Immenhauser et al ., 2004; Gili et al ., 2016; Graziano & Raspini, 2018; Posenato et al ., 2018, among others) and the proto‐North Atlantic (e.g. Phelps et al ., 2014; Núñez‐Useche et al ., 2020).…”

Section: Introductionmentioning

confidence: 99%

Proliferation of Chondrodonta as a proxy of environmental instability at the onset of OAE1a: Insights from shallow‐water limestones of the Apulia Carbonate Platform

et al. 2021

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Chondrodonta is an opportunistic, oyster-like bivalve, common in shallowwater carbonates of the Cretaceous Tethyan Realm. Despite its high abundance and widespread geographic distribution, the precise relationship between the early Aptian proliferation and environmental perturbations resulting from the Oceanic Anoxic Event 1a (OAE1a), has not been investigated. Stratigraphic and geochemical analyses of the lower Aptian Chondrodonta bedsets within the inner platform limestones of the Apulia Carbonate Platform (Gargano Promontory, southern Italy) are conducted to assess the environmental controls on the Chondrodonta proliferation and its timing and causal relationship to OAE1a. Chondrodonta occurs with sparse to common individuals within requieniid rudist floatstone-rudstones, forms monospecific biostromes during the early phase of stressed environmental conditions and then rapidly disappears at the peak of OAE1a. It proliferates in dysoxic seawater with relatively increased trophic sources, which correlate to increasing nutrient levels in the nearby pelagic realm. Chondrodontarich beds are associated worldwide with the onset of OAE1a and occur in a transitional context between a stable and a strongly stressed environment, where the opportunistic behaviour of Chondrodonta is rather efficient. Increasing nutrient load and unstable environmental conditions right below the peak of OAE1a created an environmental 'window' favourable for Chondrodonta to proliferate, outplaying the less tolerant benthos (for example, rudists). The occurrence, duration and position of the environmental window were controlled by local palaeogeographic and hydrodynamic settings (i.e. low energy, decreased seawater oxygenation and circulation). Further increase in inhospitable conditions, leading to OAE1a, constituted an upper threshold for Chondrodonta and allowed mesotrophic taxa like Bacinella-Lithocodium and orbitolinids to dominate the benthic 3191

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High-resolution chronostratigraphy of palaeoecologic and isotopic changes in shallow-marine carbonates: Deciphering the completeness of the Aptian record in the Apennine carbonate platform (southern Italy)

Cited by 13 publications

References 214 publications

Regional palaeoenvironmental influence on organic matter sequestration and characteristics of carbon isotope segment C5 in a hemipelagic sequence, Organyà Basin, northeast Spain

Regional palaeoenvironmental influence on organic matter sequestration and characteristics of carbon isotope segment C5 in a hemipelagic sequence, Organyà Basin, northeast Spain

Chemostratigraphic characteristics of trace elements, biomarkers and clay mineralogy indicating environmental conditions within Aptian sediments of the Organyà Basin, North‐east Spain, prior to the onset of OAE 1a

Proliferation of Chondrodonta as a proxy of environmental instability at the onset of OAE1a: Insights from shallow‐water limestones of the Apulia Carbonate Platform

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