Calcareous benthonic foraminifera across the Cretaceous/Paleocene transition of Gebel Um El-Ghanayem, Kharga Oasis, Egypt

Orabi, Orabi H.; Khalil, Hamza M.

doi:10.1016/j.jafrearsci.2014.03.017

Cited by 14 publications

(3 citation statements)

References 57 publications

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“…3C, Table 2), suggesting that they have similar ecological preferences, including a tolerance for suboxic conditions and refractory organic matter. This interpretation is consistent with that for other buliminiids, which are usually cylindrical and tapered and associated with high fluxes of low-quality organic matter (Koutsoukos et al 1990; Coccioni and Galeotti 1993; Gooday 1993; Ortiz et al 2011; Orabi and Khalil 2014; Deprez et al 2017; Arreguín-Rodriguez et al 2021). Thus, B. fabilis can be used as an additional indicator of environments with refractory organic matter and suboxic conditions.…”

Section: Discussionsupporting

confidence: 89%

Spatial heterogeneity in benthic foraminiferal assemblages tracks regional impacts of paleoenvironmental change across Cretaceous OAE2

Bryant

Belanger²

2023

Paleobiology

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The impact of global climate events on local ecosystems can vary spatially. Understanding this potential heterogeneity can illuminate which environments will be most impacted and the proximal drivers of ecosystem responses. Cenomanian–Turonian marine deposits of the Western Interior Seaway (WIS) record paleoceanographic changes associated with the Greenhorn transgression and the onset of Oceanic Anoxic Event 2 (OAE2). They provide an ideal setting to study basin-wide paleoecological responses during a global perturbation. Here, we integrate benthic foraminiferal assemblages from before, during, and after OAE2 via multivariate ordination analysis to examine spatial patterns in faunal responses across the western United States on a common scale and to interrogate a previously defined faunal marker commonly used for basin-wide correlation, the Benthonic Zone (BZ). We identify oxygenation and organic matter quality as primary and secondary controls of faunal variation across the 10 stratigraphic records and use this variation to infer paleoenvironmental changes. Stratigraphic trends reveal, in contrast to previous studies, deoxygenation at the onset of OAE2. They also reveal temporal patterns in oxygenation and productivity consistent with the gradual northward migration of a southern water mass into the WIS. This spatial heterogeneity hinders the use of the BZ as a temporal marker, because assemblages change in response to diachronous environmental change, and thus timing of the BZ with respect to OAE2 is not consistent across the basin. Our study demonstrates that regional processes can overshadow ecosystem responses to global events and underscores the importance of considering how changes in the position of water masses impact the expression of global biogeochemical perturbations.

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Section: Discussionsupporting

confidence: 89%

Spatial heterogeneity in benthic foraminiferal assemblages tracks regional impacts of paleoenvironmental change across Cretaceous OAE2

Bryant

Belanger²

2023

Paleobiology

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“…The Upper Cretaceous – lower Palaeogene stratigraphic succession exposed in the Western Desert has been the subject of intensive studies (Le Roy, 1953; Said & Kerdany, 1961; Hewaidy & Cherif, 1984; Luger, 1985, 1988; Anan & Hewaidy, 1986; Cherif & Hewaidy, 1986; Hewaidy, 1990; Samir, 1995; Schnack, 2000; Hewaidy & Strougo, 2001; Hewaidy et al 2014; Orabi & Khalil, 2014; Farouk & El-Sorogy, 2015; El-Dawy et al 2016). However, palaeoenvironment and palaeobathymetry studies using smaller benthic foraminifera have been scarce, especially in the Dakhla Oasis (Schnack, 2000; Hewaidy et al 2014) (Fig.…”

Section: Introductionmentioning

confidence: 99%

Benthic foraminiferal response to relative sea-level changes in the Maastrichtian–Danian succession at the Dakhla Oasis, Western Desert, Egypt

Farouk

Jain

2016

Geol. Mag.

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The Maastrichtian–Danian benthic foraminiferal diversity and assemblages through sequence stratigraphy were studied at Dakhla Oasis, Egypt. Benthic foraminifera numbers (BFN), high-flux species and characteristic benthic foraminiferal species and genera distribution are also incorporated to assess palaeobathymetry, palaeoenvironment and palaeoproductivity. All these proxies are then taken together to construct a sea-level curve and interpreted in terms of regional tectonics, climate and eustasy. Data suggest a remarkably highly equitable benthic environment deposited in a brackish littoral and/or marsh setting with moderate (?) to low oxygen conditions and reduced salinity (oligotrophic), possibly due to increased precipitation and terrestrial runoff. The interrupted dominance of calcareous forms and high-organic-flux species suggests occasional marine incursions and high palaeoproductivity, due to local upwelling. The inferred sea-level curve replicates the global eustatic curve and suggests that the curve is more influenced by the prevailing climate and global eustasy rather than by regional tectonics. The post-Cretaceous–Palaeogene boundary displays improvement in the environment in terms of diversity and number of species and specimens, with a marked reduction in the abundance of high-organic-flux species during early Paleocene (Danian) time, indicating a shift from a more mesotrophic open marine environment to much reduced oligotrophic conditions.

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“…It must be noted right away that there are two competing theories on whether there was a gap (hiatus) or continuous sedimentation in Egypt based on data derived from planktonic foraminifera, benthic foraminifera, and calcareous nannofossils. Beckmann et al, (1969) stated that most sections in Egypt show a clear hiatus at the K/Pg boundary and this has been corroborated by others too in the Western Desert (Abdel-Kireem and Samir, 1995; Tantawy et al, 2001;Khalil and Al Sawy, 2014;Orabi and Khalil, 2014;Farouk and Faris, 2012;Farouk, 2016), in the Nile Valley (Faris et al, 1985), in the Eastern Desert (Scheibner et al, 2003;Galal and Kamel, 2007), and in Sinai (Ayyad et al, 2003). However, El-Bassiouni et al, (2003) and Obaidalla (2005) have advocated a continuous sedimentation.…”

Section: [Insert Here -Figure 1]mentioning

confidence: 77%

Relationship of Maastrichtian–Thanetian benthic foraminiferal species diversity, palaeooxygenation, and palaeoproductivity in shallow waters of the Western Desert, Egypt

et al. 2023

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Benthic foraminiferal analysis (315 samples, 16,271 specimens) of the shallow water (< 100 m) Maastrichtian-Thanetian rocks from the Dakhla Oasis (Western Desert, Egypt) were studied to infer the inter-relationships between species diversity, palaeooxygenation, palaeoproductivity, and palaeodepth and changes at the Cretaceous-Paleogene (K/Pg) boundary. Positive and signi cant correlations are noted between these proxies, suggesting a well-oxygenated oligotrophic environment. However, a brief interval (mid-lower Maastrichtian) of increased palaeoproductivity with reduced diversity and oxygenation (ventilation) is noted (a characteristic of mesotrophic-eutrophic settings) that coincides with very shallow waters during a Highstand System Tract (HST), and dominated by the dysoxic agglutinated species Ammobaculites khargaensis. The diversity index, Fisher's α (< 5) and paleodepth proxy (foraminiferal wall structure types) also suggests a shallow neritic (largely littoral) depth for the entire study interval. At the bottom of the study section (Planktic Foraminiferal Zones CF8b-CF7), species diversity, palaeooxygenation, and palaeoproductivity are high. From the K/Pg boundary to the post K/Pg period, these variables are low and uctuating with moderate species dominance. According to the available data, a 40% total extinction rate was seen after the K/Pg hiatus, with 38% of agglutinated species and 40% of calcareous extinct species. The period immediately following the K/Pg boundary is characterised by increased basinal ventilation and decreased palaeoproductivity, which are attributable to changes in sea level and concurrent regional subsidence. However, as stable as the community structure was (at or just after K/Pg), the changes in species composition (assemblage) were dramatic marked by a change from a pre-K/Pg agglutinated-dominated fauna (Haplophragmoides-Ammobaculites) to a post-K/Pg calcareous assemblage (Cibicodoides-Cibicides-Anomalinoides). IntroductionThe benthic foraminiferal species assemblage, distribution, and community structure are a result of the interaction between productivity (the organic-ux to the sea oor) and pore waters and oxygenation of the bottom (Van der Jorissen et al., 2007). However, in the deep sea environment, oxygen availability is frequently and not a limiting factor, where the characteristics of individual species or assemblages (or the composition of an assemblage) are frequently good ux-indicators. In shallower waters, it is di cult to distinguish between the individual effects of oxygen and organic-ux ( Van der Zwaan et al., 1999;Jorissen et al., 2007). In modern oceans, the quantity, quality and periodicity of organic-ux to the sea oor de ne the distribution of benthic foraminiferal fauna; although, there is still "a great deal of uncertainty about the downward ux of organic carbon" to the sea oor and the estimates of primary production (see review by Murray, 2001).The Upper Cretaceous-Lower Paleogene interval has been extensively studied in order to better understand the respon...

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Calcareous benthonic foraminifera across the Cretaceous/Paleocene transition of Gebel Um El-Ghanayem, Kharga Oasis, Egypt

Cited by 14 publications

References 57 publications

Spatial heterogeneity in benthic foraminiferal assemblages tracks regional impacts of paleoenvironmental change across Cretaceous OAE2

Spatial heterogeneity in benthic foraminiferal assemblages tracks regional impacts of paleoenvironmental change across Cretaceous OAE2

Benthic foraminiferal response to relative sea-level changes in the Maastrichtian–Danian succession at the Dakhla Oasis, Western Desert, Egypt

Relationship of Maastrichtian–Thanetian benthic foraminiferal species diversity, palaeooxygenation, and palaeoproductivity in shallow waters of the Western Desert, Egypt

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