Textures in spinel peridotite mantle xenoliths using micro-CT scanning: Examples from Canary Islands and France

We performed an exploratory analysis of the morphology of the cranium in the white olm (Proteus anguinus anguinus) and the black olm (P. a. parkelj) with micro-CT scanning and geometric morphometrics. The mudpuppy (Necturus maculosus) was used as an outgroup. The black olm falls outside the white olm morphospace by a markedly wider skull, shorter vomers which are positioned further apart and by laterally positioned squamosals and quadrates relative to the palate (the shape of the buccal cavity). On account of its robust skull with more developed premaxillae a shorter otico-occipital region, the black olm is positioned closer to Necturus than are the studied specimens of the white olm. The elongated skull of the white olm, with an anteriorly positioned jaw articulation point, could be regarded as an adaptation for improved feeding success, possibly compensating for lack of vision. As yet, the alternative explanations on the evolution of troglomorphism in Proteus are an extensive convergence in white olms versus the reverse evolution towards less troglomorphic character states in the black olm. To further understand the evolutionary trajectories within Proteus we highlight the following hypotheses for future testing: i) morphological differentiation is smaller within than between genetically differentiated white olm lineages, and ii) ontogenetic shape changes are congruent with the shape changes between lineages. We anticipate that the morphological detail and analytical power that come with the techniques we here employed will assist us in this task.

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Phlogopite-pargasite coexistence in an oxygen reduced spinel-peridotite ambient

Scientific Reports ◽

10.1038/s41598-021-90844-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Costanza Bonadiman ◽

Valentina Brombin ◽

Giovanni B. Andreozzi ◽

Piera Benna ◽

Massimo Coltorti ◽

...

Keyword(s):

Oxygen Fugacity ◽

Upper Mantle ◽

Mantle Xenoliths ◽

Spinel Peridotite ◽

Simultaneous Formation ◽

Empirical Potentials ◽

Elastic Data ◽

Mineralogical Study ◽

Semi Empirical ◽

T Locus

AbstractThe occurrence of phlogopite and amphibole in mantle ultramafic rocks is widely accepted as the modal effect of metasomatism in the upper mantle. However, their simultaneous formation during metasomatic events and the related sub-solidus equilibrium with the peridotite has not been extensively studied. In this work, we discuss the geochemical conditions at which the pargasite-phlogopite assemblage becomes stable, through the investigation of two mantle xenoliths from Mount Leura (Victoria State, Australia) that bear phlogopite and the phlogopite + amphibole (pargasite) pair disseminated in a harzburgite matrix. Combining a mineralogical study and thermodynamic modelling, we predict that the P–T locus of the equilibrium reaction pargasite + forsterite = Na-phlogopite + 2 diopside + spinel, over the range 1.3–3.0 GPa/540–1500 K, yields a negative Clapeyron slope of -0.003 GPa K–1 (on average). The intersection of the P–T locus of supposed equilibrium with the new mantle geotherm calculated in this work allowed us to state that the Mount Leura xenoliths achieved equilibrium at 2.3 GPa /1190 K, that represents a plausible depth of ~ 70 km. Metasomatic K-Na-OH rich fluids stabilize hydrous phases. This has been modelled by the following equilibrium equation: 2 (K,Na)-phlogopite + forsterite = 7/2 enstatite + spinel + fluid (components: Na2O,K2O,H2O). Using quantum-mechanics, semi-empirical potentials, lattice dynamics and observed thermo-elastic data, we concluded that K-Na-OH rich fluids are not effective metasomatic agents to convey alkali species across the upper mantle, as the fluids are highly reactive with the ultramafic system and favour the rapid formation of phlogopite and amphibole. In addition, oxygen fugacity estimates of the Mount Leura mantle xenoliths [Δ(FMQ) = –1.97 ± 0.35; –1.83 ± 0.36] indicate a more reducing mantle environment than what is expected from the occurrence of phlogopite and amphibole in spinel-bearing peridotites. This is accounted for by our model of full molecular dissociation of the fluid and incorporation of the O-H-K-Na species into (OH)-K-Na-bearing mineral phases (phlogopite and amphibole), that leads to a peridotite metasomatized ambient characterized by reduced oxygen fugacity.

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A Microcomputed Tomographic Evaluation of Root Canal Morphology of Maxillary Second Premolars in a Pakistani Cohort

Applied Sciences ◽

10.3390/app11115086 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5086

Author(s):

Mazen F. Alkahtany ◽

Saqib Ali ◽

Abdul Khabeer ◽

Shafqat A. Shah ◽

Khalid H. Almadi ◽

...

Keyword(s):

Root Canal ◽

Three Dimensional ◽

Ct Scanning ◽

Micro Ct ◽

Single Root ◽

Root Canal Morphology ◽

Spss Software ◽

Variable Morphology ◽

Canal Morphology

This study aimed to investigate variations in the root canal morphology of maxillary second premolar (MSP) teeth using microcomputed tomography (micro-CT). Sixty (N = 60) human extracted MSPs were collected and prepared for micro-CT scanning. The duration for scanning a single sample ranged between 30 and 40 min and a three-dimensional (3-D) image was obtained for all the MSPs. The images were evaluated by a single observer who recorded the canal morphology type, number of roots, canal orifices, apical foramina(s), apical delta(s), and accessory canals. The root canal configuration was categorized in agreement with Vertucci’s classification, and any configuration not in agreement with Vertucci’s classification was reported as an “additional canal configuration”. Descriptive statistics (such as mean percentages) were calculated using SPSS software. The most common types agreeing with Vertucci’s classification (in order of highest to lowest incidence) were types I, III, V, VII, II, and VI. The teeth also exhibited four additional configurations that were different from Vertucci’s classification: types 2-3, 1-2-3, 2-1-2-1, and 1-2-1-3. A single root was found in 96.7% and the majority of the samples demonstrated two canals (73.3%). Further, 80% of the teeth showed one canal orifice. The number of apical foramina’s in the teeth was variable, with 56.7% having solitary apical foramen. The accessory canal was found in 33.3%, and apical delta was found in only 20% of the samples. Variable morphology of the MSPs was detected in our study. The canal configuration most prevalent was type 1; however, the results also revealed some additional canal types.

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Timing of Mouse Molar Formation Is Independent of Jaw Length Including Retromolar Space

Journal of Developmental Biology ◽

10.3390/jdb9010008 ◽

2021 ◽

Vol 9 (1) ◽

pp. 8

Author(s):

Daisy (Jihyung) Ko ◽

Tess Kelly ◽

Lacey Thompson ◽

Jasmene K. Uppal ◽

Nasim Rostampour ◽

...

Keyword(s):

Onset Time ◽

Ct Scanning ◽

Micro Ct ◽

Third Molars ◽

Developmental Duration ◽

Dental Lamina ◽

Permanent Molars ◽

Dental Epithelium ◽

Space Conditions

For humans and other mammals to eat effectively, teeth must develop properly inside the jaw. Deciphering craniodental integration is central to explaining the timely formation of permanent molars, including third molars which are often impacted in humans, and to clarifying how teeth and jaws fit, function and evolve together. A factor long-posited to influence molar onset time is the jaw space available for each molar organ to form within. Here, we tested whether each successive molar initiates only after a minimum threshold of space is created via jaw growth. We used synchrotron-based micro-CT scanning to assess developing molars in situ within jaws of C57BL/6J mice aged E10 to P32, encompassing molar onset to emergence. We compared total jaw, retromolar and molar lengths, and molar onset times, between upper and lower jaws. Initiation time and developmental duration were comparable between molar upper and lower counterparts despite shorter, slower-growing retromolar space in the upper jaw, and despite size differences between upper and lower molars. Timing of molar formation appears unmoved by jaw length including space. Conditions within the dental lamina likely influence molar onset much more than surrounding jaw tissues. We theorize that molar initiation is contingent on sufficient surface area for the physical reorganization of dental epithelium and its invagination of underlying mesenchyme.

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Leveraging Micro-CT Scanning to Analyze Parasitic Plant-Host Interactions

Journal of Visualized Experiments ◽

10.3791/63423 ◽

2022 ◽

Author(s):

Luiza Teixeira-Costa

Keyword(s):

Ct Scanning ◽

Parasitic Plant ◽

Micro Ct ◽

Plant Host ◽

Host Interactions

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MicroCT protocols for scanning of embryos and juvenile Hexaplex trunculus v1

10.17504/protocols.io.bxw4ppgw ◽

2021 ◽

Author(s):

Eva Chatzinikolaou ◽

Kleoniki Keklikoglou

Keyword(s):

Computed Tomography ◽

High Resolution ◽

3D Imaging ◽

Imaging Technique ◽

Ct Scanning ◽

Micro Ct ◽

Micro Computed Tomography ◽

Gastropod Species ◽

Biological Studies ◽

Hexaplex Trunculus

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. This protocol aims to standardise micro-CT scanning procedures for embryos and juveniles of the marine gastropod species Hexaplex trunculus.

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