Larger Benthic Foraminifera from the Panna and Mukta Fields Offshore India: Paleobiogeographical Implications

2019 ◽  
Vol 49 (3) ◽  
pp. 243-258
Author(s):  
Laura J. Cotton ◽  
V. Paul Wright ◽  
Andrew Barnett ◽  
Willem Renema
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Late Eocene ◽  
Marine Biodiversity ◽  
Upper Eocene ◽  
Larger Benthic Foraminifera ◽  
Geographic Ranges ◽  
Extinction Event ◽  
Global Events ◽  
Insight Into

Abstract A previously undocumented, diverse assemblage of very shallow-water larger benthic foraminifera (LBF) is described from the Panna-Mukta fields, offshore India. This location lies at the margin of the late Eocene to early Miocene Arabian Peninsula marine biodiversity hotspot. The assemblage has similar characteristics to those from the Middle East, Oman and Turkey, but shares little in common with onshore western Indian assemblages. In addition, the material contains several unusual and possibly new taxa, and extends the geographic ranges of several existing LBF. The succession spans the Eocene and Oligocene, with an unconformity between the middle and upper Eocene. As such it offers insight into the response of shallow-water taxa to the Eocene–Oligocene Transition extinction event from an unusual setting in a little studied region. Our data show that LBF taxonomic richness in the Panna Mukta fields is comparable with highly diverse assemblages found in Oman, indicating it may be an eastward extension of this high diversity region. Moreover, significant decreases in diversity are seen between the middle and upper Eocene and the upper Eocene and Oligocene. Major extinctions are known to occur in global LBF records at both of these levels, and the Panna Mukta succession therefore further confirms these are global events, extending across the platform and having a dramatic (at least short-term) effect on high biodiversity regions.

Imperforate Larger Benthic Foraminifera from Shallow-water Carbonate Facies (middle and Late Eocene), Zagros Mountains, Iran

2019 ◽  
Vol 49 (3) ◽  
pp. 275-302 ◽  
Author(s):  
Elham Nafarieh ◽  
Carme Boix ◽  
Erzika Cruz-Abad ◽  
Ebrahim Ghasemi-Nejad ◽  
Alireza Tahmasbi ◽  
...  
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Late Eocene ◽  
Photic Zone ◽  
Zagros Mountains ◽  
Carbonate Facies ◽  
Foraminiferal Assemblage ◽  
Larger Benthic Foraminifera ◽  
Water Carbonate ◽  
Shallow Water Carbonate

Abstract We studied the architecture and biostratigraphical distribution of the imperforate larger benthic foraminifera from the upper part of the Jarhum Formation in the Fars Interior (Zagros, Iran) and identified 15 taxa belonging to the families Coskinolinidae, Orbitolinidae, Austrillinidae, Praerhapydioninidae and Soritidae. This foraminiferal assemblage indicates deposition in warm, shallow (upper photic zone), relatively oligotrophic conditions compatible with an inner-ramp setting. The age attributed to the assemblage is Bartonian-earliest Priabonian.

Selectivity of foraminiferal extinction in the late Eocene

Paleobiology ◽  
1997 ◽  
Vol 23 (3) ◽  
pp. 347-357 ◽  
Author(s):  
Amit Banerjee ◽  
George E. Boyajian
Keyword(s):  
Benthic Foraminifera ◽  
Middle Eocene ◽  
Late Eocene ◽  
Mass Extinctions ◽  
Larger Benthic Foraminifera ◽  
Late Paleocene ◽  
Risk Of Extinction ◽  
Extinction Event

Late Eocene foraminiferal extinction shows diverse patterns of selective morphologic and latitudinal extinction. Taxa with discoidal shape, calcareous tests, and narrow and low-latitudinal ranges are at significantly greater risk of extinction. Elevated extinction intensities in calcareous tests are mainly due to the presence of larger benthic foraminifera that evolved in late Paleocene and diversified through the lower to middle Eocene. Selectivity of late Eocene foraminiferal extinction indicates that this extinction event was not a globally uniform event. Although this result does not verify an extraterrestrial impact or any other proposed cause of extinction, it does constrain the causes of late Eocene extinction. Furthermore, the geography of late Eocene foraminiferal extinction, and previously studied Cenomanian/Turonian extinction, demonstrates that mass extinctions exhibit different patterns of selectivity.

The propagule method as a tool to study assemblage dynamics in benthic foraminifera: An example with pH variations

2021 ◽  
Author(s):  
Anna E. Weinmann ◽  
Susan T. Goldstein ◽  
Maria V. Triantaphyllou ◽  
Martin R. Langer
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Ph Gradients ◽  
Local Conditions ◽  
Recovery Mechanisms ◽  
Decreasing Ph ◽  
Set Up ◽  
Ph Variations ◽  
Insight Into

<p>Benthic foraminifera are important indicators for ecological studies. The assemblage composition of local communities can be used to analyze influences of environmental variables such as temperature, salinity, pH, and others. In recent years, the experimental propagule method has emerged as an effective tool to evaluate the influence of these variables on assemblage dynamics of benthic foraminifera. Propagules (tiny juveniles) of benthic foraminifera are widespread and can survive outside of a species’ natural distribution range. Their ability to become dormant and be re-activated once local conditions become suitable, is an important driver behind the capacity of foraminiferal assemblages to react quickly to environmental changes. In the laboratory, the propagules are first separated from the coarser fractions by sieving and then cultured under different conditions.</p><p>In the present study, we analyzed the effect of ocean pH on the composition of shallow-water assemblages from Corfu Island (Greece). Like other calcifying organisms, assemblages of foraminifera are susceptible to pH variations and have revealed compositional shifts along natural or experimental pH gradients. Our experimental set-up included four pH treatments between 6.5 and 8.5 at constant temperature and salinity (22°C and 38 ppt) for 5 weeks.</p><p>At the conclusion of the cultivation experiment, we found high numbers of grown specimens (825–1564 per replicate) and a high survivability rate throughout all treatments (78–87%). Higher pH (7.8 and 8.5) resulted in assemblages that were dominated by monothalamous and porcelaneous species, whereas lower pH (6.5 and 7.2) lead to a reduction in porcelaneous and an increase in agglutinated species. Several taxa showed significant positive or negative correlations with decreasing pH values.</p><p>Our results are congruent with previous findings that reported compositional shifts from calcareous to agglutinated taxa with decreasing pH (both from culture and field observations). Our study also indicates that the activation of propagules is an important mechanism behind assemblage dynamics in shallow-water foraminifera. As such, it offers an improved insight into potential resilience and recovery mechanisms of foraminiferal assemblages with regard to local or seasonal pH variations as well as ongoing ocean acidification.</p>

The incidence of unusual test morphologies of Eocene Larger benthic foraminifera: An example of Paleogene Adriatic Carbonate Platform

2021 ◽  
Author(s):  
Vlasta Ćosović ◽  
Jelena Španiček ◽  
Katica Drobne ◽  
Ervin Mrinjek
Keyword(s):  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Middle Eocene ◽  
Morphological Diversity ◽  
Late Eocene ◽  
Early Eocene ◽  
Coralline Red Algae ◽  
Larger Benthic Foraminifera ◽  
Shallow Marine ◽  
Scientific Project

<p>The Paleogene Adriatic carbonate platform(s) existed within the Central NeoTethys (around 32 N paleolatitude) from the Danian to the late Eocene (Bartonian/Priabonian) and produced a succession of limestones up to 500 m thick, rich in larger benthic foraminifera (LBF). The Eocene sediments are widely distributed along the eastern Adriatic coast and have been studied for many years. Taking into account the climatic changes that took place within the Eocene (Early Eocene and Middle Eocene climatic optima, known as EECO, MECO), special attention was paid to the composition of shallow-marine foraminiferal assemblages. The studies reveal the following trends: (1) the alveolinid-dominated assemblages were replaced by nummulitid-dominated assemblages around the MECO; (2) the greater species and morphological diversity (spherical, ellipsoid, extremely elongated fusiform) of the alveolinid fauna was evident at the EECO; (3) the nummulitid-dominated fauna was characterized by less diversified assemblages compared to the alveolinid ones and by the co-occurrence of scleractinian corals, coralline red algae and aborescent foraminifera. The occurrence of twin embryos has been assigned to the early Eocene in the alveolinid populations, especially in Alveolina levantina and A. axiampla (in some sections, the frequency is greater than 5%), and these coalesced embryos have the same size as the single form (usually they are smaller). The LBF assemblages of Middle Eocene showed a greater frequency of doubled adult tests (Orbitolites sp., Nummulites sp.). The origin of these unusual morphologies is poorly known, usually described as the results of stressful conditions. Considering the timing of the appearance of such morphologies, temperature and associated changes in the shallow-marine environment could be the cause.</p><p>This study is carried out as part of the scientific project IP-2019-04-5775 BREEMECO, funded by Croatian Scientific Foundation.</p>

scholarly journals COMMENTS ON “STRATIGRAPHIC DISTRIBUTION OF SHALLOW-WATER BENTHIC FORAMINIFERA FROM THE LOWER CRETACEOUS TAFT FORMATION, CENTRAL IRAN (YAZD BLOCK), WITH EVIDENCE FOR THE IMPORTANCE OF HIATUSES” BY GHEIASVAND, M. ET AL. [ANNALES DE PALÉONTOLOGIE, 2020, 154 (3), 102399] AND RELATED PAPERS

2021 ◽  
pp. 3-8
Author(s):  
FELIX SCHLAGINTWEIT
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Lower Cretaceous ◽  
Central Iran ◽  
Migration Patterns ◽  
Larger Benthic Foraminifera ◽  
Multidisciplinary Study ◽  
Potential Index

Gheiasvand et al. (2020) use the two larger benthic foraminifera species Simplorbitolina manasi Ciry & Rat and Mesorbitolina parva (Douglass) (Orbitolinidae) as upper Aptian “potential index fossils” for parts of the Taft Formation in Central Iran. This age assignment is accompanied by changes to well-established orbitolinid biozona-tions (e.g. occurrence of Praeorbitolina in the late Aptian) with far-reaching implications. These data were also used in a later “multidisciplinary study” (Gheiasvand et al., 2021) for isotopic correlations (e.g., location of OAE`s), delimitation of palaeobiogeographic faunal provinces and related migration patterns. It is shown herein that the taxa identified as S. manasi and M. parva belong to Iraqia simplex Henson and Palorbitolina lenticularis (Blumenbach) respectively documenting a lower and not an upper Aptian age. This revised age and the different taxononomic inventory do not question all results obtained by Gheiasvand et al. (2020, 2021), but provide a revised basis interpretation.

scholarly journals FIRST RECORD OF CALCAREOUS GREEN ALGAE (DASYCLADALES, HALIMEDACEAE) FROM THE PALEOCENE CHEHEL KAMAN FORMATION OF NORTH-EASTERN IRAN (KOPET-DAGH BASIN)

2021 ◽  
pp. 51-64
Author(s):  
FELIX SCHLAGINTWEIT ◽  
KOOROSH RASHIDI ◽  
ABDOLMAJID MOSAVINIA
Keyword(s):  
Shallow Water ◽  
Green Algae ◽  
Benthic Foraminifera ◽  
First Record ◽  
Larger Benthic Foraminifera ◽  
Eastern Iran ◽  
North Eastern ◽  
Kopet Dagh ◽  
First Time ◽  
Upper Paleocene

The micropalaeontological inventory of the shallow-water carbonates of the Paleocene Chehel-Kaman Formation cropping out in the Kopet-Dagh Basin of north-eastern Iran is poorly known. New sampling has evidenced for the first time the occurrence of layers with abundant calcareous green algae including Dasycladales and Halimedaceae. The following dasycladalean taxa have been observed: Jodotella veslensis Morellet & Morellet, Cymopolia cf. mayaense Johnson & Kaska, Neomeris plagnensis Deloffre, Thyrsoporella-Trinocladus, Uteria aff. merienda (Elliott) and Acicularia div. sp. The studied section is devoid of larger benthic foraminifera and can be referred to the middle-upper Paleocene (SBZ 2-4) due to the presence of Rahaghia khorassanica (Rahaghi). Some of the dasycladalean taxa are herein reported for the first time not only from Iran but also the Central Neotethyan realm.

scholarly journals ORBITOLINIDS AND OTHER LARGER BENTHIC FORAMINIFERA FROM THE APTIAN-ALBIAN OF TIBET: CRITICAL DISCUSSION OF SOME RECENTLY PUBLISHED DATA

2021 ◽  
pp. 17-23
Author(s):  
FELIX SCHLAGINTWEIT
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Lower Cretaceous ◽  
Critical Discussion ◽  
Individual Species ◽  
Published Data ◽  
Larger Benthic Foraminifera ◽  
Stratigraphic Ranges

Orbitolinidae together with other larger benthic foraminifera are particularly important in Lower Cretaceous shallow-water biostratigraphy provided that they are correctly identified. Especially in the case of the Orbitolininae (with complex embryo), their biostratigraphic range with overlapping ranges corresponds to different lineages displaying ancestor-descendant relationship (e.g., Praeorbitolina-Mesorbitolina). In the last fifty years well established and repeatedly confirmed taxon ranges have been largely extended thereby diluting or negating any biostratigraphic value to individual species. Some biostratigraphic data provided by BouDagher-Fadel et al. (2017) from the Aptian-Albian of Tibet that are contradicting previous results are reviewed herein. This publication mostly refers to the stratigraphic ranges of Praeorbitolina cormyi Schroeder and Pseudochoffatella cuvillieri Deloffre towards the top of the Albian, and that of Palorbitolina lenticularis (Blumenbach) into the late Aptian, as well as some misidentifications.

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