Lower Permian brachiopods from Oman: their potential as climatic proxies

Angiolini, Lucia; Darbyshire, D. P. F.; Stephenson, Michael H.; Leng, Melanie J.; Brewer, T. S.; Berra, Fabrizio; Jadoul, Flavio

doi:10.1017/s1755691008075634

Cited by 13 publications

(15 citation statements)

References 55 publications

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“…Growth lines show a weak luminescence, but this may be a primary feature (Angiolini et al . , ). Fractures (from a few microns up to 1 mm wide) occur, filled either with brightly luminescent calcite or dull luminescent calcite followed by dolomite euhedral rhombs (Fig.…”

Section: Resultsmentioning

confidence: 99%

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The giants of the phylum Brachiopoda: a matter of diet?

et al. 2019

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The species of the brachiopod Gigantoproductus are giants within the Palaeozoic sedentary benthos. This presents a dilemma as living brachiopods have low‐energy lifestyles. Although brachiopod metabolic rates were probably higher during the Palaeozoic than today, the massive size reached by species of Gigantoproductus is nevertheless unusual. By examining the diet of Gigantoproductus species from the Visean (Mississippian, Carboniferous) of Derbyshire (UK), we seek to understand the mechanisms that enabled those low‐metabolism brachiopod species to become giants. Were they suspension feeders, similar to all other brachiopods, or did endosymbiosis provide a lifestyle that allowed them to have higher metabolic rates and become giants? We suggest that the answer to this conundrum may be solved by the identification of the biogeochemical signatures of symbionts, through combined analyses of the carbon and nitrogen‐isotopic compositions of the occluded organic matrix within their calcite shells. The shells are formed of substructured columnar units that are remarkably long and a few hundreds of microns wide, deemed to be mostly pristine based on multiple analyses (petrography, cathodoluminescence (CL), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM)); they contain occluded organic fractions detected by TEM, nuclear magnetic resonance (NMR) and gas chromatography mass spectrometry (GC‐MS) analyses. We conclude that the gigantic size reached by the species of Gigantoproductus is probably the result of a mixotroph lifestyle, by which they could rely on the energy and nutrients derived both from photosymbiotic microbes and from filtered particulate food.

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Section: Resultsmentioning

confidence: 99%

“…The sectioned specimens were etched with 5% HCl for 20 s before coating with gold to examine the preservation of their shell fabric under SEM following the methodology described in Angiolini et al . (, ).…”

Section: Methodsmentioning

confidence: 99%

The giants of the phylum Brachiopoda: a matter of diet?

et al. 2019

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“…The mineralogy of the shell can be tested using X-ray diffraction (XRD) or Raman spectroscopy. There are several other tests of preservation which include examination of the ultrastructure of the shell carbonate and examination of the carbonate under cathodoluminescence to check for signs of recrystallisation (Angiolini et al 2008, and major element chemistry , although these tend to be applied to geological (rather than archaeological) aged material.…”

Section: Preservation and Analytical Methodsmentioning

confidence: 99%

Oxygen isotopes in Molluscan shell: Applications in environmental archaeology

Leng

Lewis

2014

Environmental Archaeology

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Oxygen isotope geochemistry of Molluscan shell is an essential part of environmental archaeology and over the last decade has contributed significantly to the understanding of the past inhabitants of our planet. From the analysis of collected (and disposed of) shells we can gain information on environmental data from the species assemblages and also from the shell chemistry. In particular, intra-seasonal information can be gained from shells by analysing the isotope composition of the shell from successive growth increments. Here, we describe some of the recent developments in the use of oxygen isotopes in environmental archaeology. In particular, we consider preservation and sampling and describe how δ 18O can provide us with information on seasonal climate, season of collection as well as changes in global climate.

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“…Well-preserved fossil brachiopods, that were abundant in the Paleozoic seas, have been proven to retain reliable geochemical proxies for investigating the paleo-environmental conditions such as paleolatitude (climate), oceanography, and seawater composition (e.g. Veizer et al 1999;Angiolini et al 2007Angiolini et al , 2009Mii et al 2013). Their primary/near-primary oxygen-isotope compositions provide an archive of the paleotemperature of ambient seawater in which they lived, which reflects the dominant climatic and depth conditions (e.g., Azmy et al 1998Azmy et al , 2006.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of Late Ordovician dalmanelloid brachiopods from Laurentia: testing the effects of paleolatitudinal gradient

Azmy

Jin

2019

Can. J. Earth Sci.

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Dalmanelloid brachiopod shells were collected from the Upper Ordovician Lexington Formation (lower Katian) of Kentucky, Sheguindah Shale (middle Katian) on Manitoulin Island, Ontario, and the Stony Mountain Formation (upper Katian) in the Winnipeg area, Manitoba. They were investigated to test the hypothesis of paleo-latitudinal zonation of the shelly benthos. A multi-technique approach was applied to evaluate the petrographic and geochemical (isotopic and elemental) preservation of the secondary layer of shells. Preliminary conventional microscopy, cathodoluminescence (CL), and scanning electron microscopy (SEM) confirmed the retention of primary shell ultrastructure (prismatic low-Mg calcite). The geochemical diagenesis proxies (e.g., Sr, Mn, Fe, and ΣREE) show insignificant correlations with the δ18O and δ13C values, thus supporting the preservation of at least near-primary geochemical compositions. Among the three lots of shells, the mean δ18O value is the highest in those from the Lexington Formation (–4.5‰ ± 0.3‰ VPDB), lowest from the Stony Mountain Formation (–6.8‰ ± 0.4‰ VPDB), and intermediate from the Sheguindah Shale (–6.0‰ ± 0.8‰ VPDB). The relative gradient in δ18O increase is in agreement with the paleo-latitudinal gradient, with Kentucky in subtropical, southern Ontario in mid-tropical, and southern Manitoba in subequatorial latitudes. The Lexington Formation shells also have the highest mean δ13C value (0.8‰ ± 0.2‰ VPDB) and relatively high P contents (170 ± 27 ppm), suggesting higher organic productivity, which is consistent with previous interpretation of frequent upwelling of nutrient-rich cool waters along the southeastern margin of Laurentia during the Katian. The Lexington shells also have a lower mean Th/U (0.6 ± 0.6), which is consistent with blooming organic productivity that likely led to more consumption of oxygen in the water column.

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Lower Permian brachiopods from Oman: their potential as climatic proxies

Cited by 13 publications

References 55 publications

The giants of the phylum Brachiopoda: a matter of diet?

The giants of the phylum Brachiopoda: a matter of diet?

Oxygen isotopes in Molluscan shell: Applications in environmental archaeology

Geochemistry of Late Ordovician dalmanelloid brachiopods from Laurentia: testing the effects of paleolatitudinal gradient

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