scholarly journals Clay templates in Ediacaran vendotaeniaceans: Implications for the taphonomy of carbonaceous fossils

2021 ◽  
Author(s):  
B. Becker-Kerber ◽  
A. Abd Elmola ◽  
A. Zhuravlev ◽  
C. Gaucher ◽  
M.G. Simões ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Soft Tissues ◽  
Bedding Plane ◽  
Mato Grosso ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Fibrous Minerals ◽  
Mean Width ◽  
History Of ◽  
Cambrian Radiation

Although rare, sedimentary deposits containing exceptionally preserved fossils (i.e., Lagerstätten) have shaped our view on the history of life at particular intervals, such as those recording the Cambrian radiation of animals. Therefore, understanding the processes that lead to the fossilization of unmineralized tissues is crucial to better interpret these fossil assemblages. A key issue on the fossilization of exceptionally preserved fossils is linked to the role of clay minerals in the high-fidelity preservation of recalcitrant and soft tissues. Here, we show for the first time, an association of unusual fibrous clays with carbonaceous fossils (Vendotaenia) in the late Ediacaran Tamengo Formation (Mato Grosso do Sul State, western Brazil). The vendotaeniaceans occur in laminated mudstones/siltstones interpreted as being deposited in outer to distal mid-ramp depositionary settings. The fossils are characterized by ribbon-shaped compressions 0.56 mm in mean width. The fibrous clays are obliquely oriented with respect to the bedding plane, and follow the orientation of tectonically deformed structures. Our mineralogical, geochemical, and petrographic data demonstrate that these clays are mainly composed of chlorite-smectite mixed layered minerals, with >50% chlorite. Altogether, our results suggest that these fibrous minerals formed in the late-diagenetic zone to lower anchizone, reinforcing the previous idea that clay minerals associated with fossils are not necessarily related to the preservation of soft tissues. Instead, the initial preservative pathway in our fossils was probably restricted to organic matter conservation in reducing fine-grained sediments, similar to other deposits with carbonaceous fossils. This newly established mechanism, which involves the formation of clays on organic templates in the late-diagenetic zone, is likely a more widespread phenomenon than previously thought.

Multiple alteration events in the history of a sub-Huronian regolith at Lauzon Bay, Ontario

1992 ◽  
Vol 29 (3) ◽  
pp. 432-445 ◽  
Author(s):  
S. J. Sutton ◽  
J. B. Maynard
Keyword(s):  
Clay Minerals ◽  
Chemical Weathering ◽  
Analytical Techniques ◽  
Mineral Chemistry ◽  
White Mica ◽  
Low Grade ◽  
Plagioclase Feldspar ◽  
Fine Grained ◽  
History Of ◽  
Greenschist Facies Metamorphism

Confusion exists over the usefulness of chemical data from Precambrian weathering profiles in constraining models of atmospheric evolution. One difficulty is in correctly identifying ancient weathering effects and isolating them from numerous other processes that are likely to have affected such ancient rocks. In this study of a middle Precambrian granitic weathering profile, we have used several analytical techniques to separate weathering-related chemical and mineralogical changes from those resulting from other processes. The profile is exposed beneath the Huronian at Lauzon Bay in the Blind River area of Ontario and has a complex history of alteration events, addition of allochthonous material, and low-grade metamorphism. Much of this history can be deciphered, and changes in mineralogy and bulk and mineral chemistry can be assigned to separate alteration events. Specifically, the granite has undergone preweathering albitization, resulting in Na enrichment, followed by chemical weathering that corroded K-feldspar and nearly destroyed plagioclase feldspar and mica in the regolith. Clay minerals replaced feldspars, resulting in enrichment in Al, Ti, and Zr and depletion in Na, Ca, Sr, and K. Fe has also been leached. After weathering, a fine-grained 0.5 m layer of strongly weathered allochthonous material was deposited on the regolith, followed by deposition of the Matinenda Formation. Sometime after Matinenda deposition, K- and Rb-metasomatim affected the regolith and overlying sediments, converting some clays to illite and depositing secondary K-feldspar. Greenschist-facies metamorphism probably postdated this metasomatism and converted clay minerals to white mica and chlorite.

An X-ray method for studying orientation of micaceous minerals in shales, clays, and similar materials

1953 ◽  
Vol 30 (220) ◽  
pp. 71-78 ◽  
Author(s):  
G. W. Brindley
Keyword(s):  
Bedding Plane ◽  
Coarse Grained ◽  
Ray Method ◽  
X Ray ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Degree Of Orientation ◽  
Similar Materials ◽  
Ray Methods ◽  
Microscopic Techniques

Micaceous minerals, such as the micas, the chlorites, and most clay minerals, usually develop as thin lamellae parallel to the crystallographic basal plane (001). In sedimentary deposits these lamellae tend to lie parallel to the bedding plane and in slates parallel to the cleavage. Their degree of orientation is likely to vary with the conditions of formation of the material, and in the case of slates Bates (1947) has shown that it is closely related to their fissility. In relatively coarse-grained materials the degree of orientation may be studied directly by suitable microscopic techniques, but with fine-grained materials X-ray methods must be used, and even with coarser-grained materials the use of X-ray methods may have advantages, especially if a scanning technique, such as that described by Thewlis and Pollock (1950), is employed.

scholarly journals Ovarian epithelioid angiosarcoma complicating pregnancy: a case report and review of the literature

2021 ◽  
Vol 49 (5) ◽  
pp. 030006052110196
Author(s):  
Xiaotong Peng ◽  
Zhi Duan ◽  
Hongling Yin ◽  
Furong Dai ◽  
Huining Liu
Keyword(s):  
Adverse Events ◽  
Soft Tissues ◽  
Malignant Tumors ◽  
Cystic Teratoma ◽  
Abdominal Distension ◽  
Epithelioid Angiosarcoma ◽  
History Of ◽  
New Ideas ◽  
The Right ◽  
Clinical Awareness

Epithelioid angiosarcoma is a rare and highly aggressive soft tissue angiosarcoma most commonly arising in the deep soft tissues. Given that abundant vascular cavities anastomose with each other, most angiosarcomas prone to metastasis recur quickly, and the overall prognosis is poor. We report a 25-year-old woman at 24 weeks’ gestation who presented with a 1-month history of abdominal distension. Ultrasonography suggested a mass in the right adnexa, and she underwent two operations owing to uncontrolled intraperitoneal bleeding with progressive anemia. The right ovarian tumor and right adnexa were removed successively. Biopsy yielded a diagnosis of primary epithelioid angiosarcoma with mature cystic teratoma. The patient died from uncontrolled progressive bleeding 1 week after the second operation. This case revealed that epithelial angiosarcoma is a highly malignant endothelial cell tumor. The results of surgery and chemoradiotherapy tend to be poor, and the recurrence rate is high. The purpose of this study is to raise clinical awareness of epithelial angiosarcoma and its adverse events and to provide new ideas for the treatment of these adverse events. Immunohistochemical staining of pathological specimens can facilitate diagnosis. Pregnancy with malignant tumors may lead to rapid disease progression, extensive lesions, and a poor prognosis.

Features of the course of labor in women with a history of perinatal loss

2018 ◽  
pp. 66-68
Author(s):  
L.I. Vorobey ◽  
Keyword(s):  
Premature Birth ◽  
Soft Tissues ◽  
Comparison Group ◽  
Child Death ◽  
Randomized Study ◽  
Perinatal Loss ◽  
Early Discharge ◽  
State Of Health ◽  
Repeat Pregnancy ◽  
History Of

The objective: was to determine the features of the course of labor in women with a history of perinatal lesions. Materials and methods. A prospective, concurrent, controlled, randomized study was conducted involving 68 women aged 26.8 ±0.5 years, with a gestation period of 28.1 ±0.56 weeks, 41 of whom had perinatal history lesions (main group) and comparable for anthropodemographic indicators and terms of gestation of 27 women with a repeat pregnancy without abortion or unsuccessful childbirth (child death) in the history (comparison group). Results. In the anamnestic aspect, the characteristics of pregnant women with a history of perinatal losses are a relatively shorter interval between repeated pregnancies, a more frequent development of extragenital pathology - the respiratory, nervous, endocrine, cardiovascular and orthopedic disorders, and a higher incidence of gynecological anamnesis. In the context of complications of delivery, women with perinatal losses are characterized by premature birth, anomalies of labor, early discharge of amniotic fluid, ruptures of soft tissues. Conclusion. It is necessary to make a comparative analysis of the course of pregnancy, childbirth and the state of health of newborns in women with a history of obstetrical anamnesis in connection with violations of neurovegetative regulation. Key words: perinatal losses, anamnesis, childbirth, current.

Becker's Nevus Syndrome

2018 ◽  
Vol 16 (05) ◽  
pp. 352-361 ◽  
Author(s):  
Maria Cucuzza ◽  
Sara Paternò ◽  
Stefano Catanzaro ◽  
Agata Polizzi ◽  
Carmelo Schepis ◽  
...  
Keyword(s):  
Natural History ◽  
Soft Tissues ◽  
Cutaneous Lesion ◽  
Simultaneous Occurrence ◽  
Pectus Carinatum ◽  
Epidermal Nevus ◽  
Becker’S Nevus ◽  
History Of ◽  
Prepubertal Boys ◽  
Postzygotic Mutations

The simultaneous occurrence of a patch of light or dark brown hyperpigmentation with hypertrichosis (Becker's nevus) together with (usually ipsilateral) soft tissues hypoplasia (especially breast, in women) and underlying skeletal anomalies (i.e., vertebral hypoplasia, scoliosis, pectus carinatum or excavatum) represents the Becker's nevus syndrome (BNS) phenotype. It was first described (as a single cutaneous lesion) by Becker in 1949 and then associated with the surrounding musculoskeletal disorders. The syndrome has also been reported as pigmentary hairy epidermal nevus syndrome. Less than 100 cases have been reported in the literature, with a slightly higher incidence in females and only few familiar cases: paradominant postzygotic mutations and/or an androgen-dependent hyperactivation have been reported as the causes of the diseases.The extracutaneous lesions are congenital and nonprogressive, and the natural history of the Becker's nevus is the same as that of isolated nevi: in prepubertal boys, the pigmentation may be less intense and the hairiness may be absent or mild, as occurs in women, whereas in men, there is an increase of hairiness after puberty. The treatment is essentially cosmetic, and potential therapeutic options include electrolysis, waxing, makeup, or laser.

Life history of the Mato Grosso Antbird Cercomacra melanaria in the Brazilian Pantanal

Ibis ◽  
2006 ◽  
Vol 148 (2) ◽  
pp. 321-329 ◽  
Author(s):  
JOÃO BATISTA DE PINHO ◽  
LEONARDO ESTEVES LOPES ◽  
DRÁUSIO HONÓRIO DE MORAIS ◽  
ALEXANDRE MENDES FERNANDES
Keyword(s):  
Life History ◽  
Mato Grosso ◽  
History Of ◽  
Brazilian Pantanal

Use of pyrite microfabric as a key to tectono-thermal evolution of massive sulphide deposits – an example from Deri, southern Rajasthan, India

1998 ◽  
Vol 62 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Anju Tiwary ◽  
Mihir Deb ◽  
Nigel J. Cook
Keyword(s):  
Thermal Evolution ◽  
Regional Metamorphism ◽  
Massive Sulphide ◽  
Ductile Deformation ◽  
Sulphide Deposit ◽  
Fine Grained ◽  
Thermal Metamorphism ◽  
Sulphide Ores ◽  
History Of ◽  
South Delhi Fold Belt

AbstractPyrite is an ubiquitous constituent of the Proterozoic massive sulphide deposit at Deri, in the South Delhi Fold Belt of southern Rajasthan. Preserved pyrite microfabrics in the Zn-Pb-Cu sulphide ores of Deri reveal a polyphase growth history of the iron sulphide and enable the tectono-thermal evolution of the deposit to be reconstructed.Primary sedimentary features in Deri pyrites are preserved as compositional banding. Regional metamorphism from mid-greenschist to low amphibolite facies is recorded by various microtextures of pyrite. Trails of fine grained pyrite inclusions within hornblende porphyroblasts define S1-schistosity. Pyrite boudins aligned parallel to S1 mark the brittle–ductile transformation of pyrite during the earliest deformation in the region. Isoclinal to tight folds (F1 and F2) in pyrite layers relate to a ductile deformation stage during progressive regional metamorphism. Peak metamorphic conditions around 550°C, an estimation supported by garnet–biotite thermometry, resulted in annealing of pyrite grains, while porphyroblastic growth of pyrite (up to 900 µm) took place along the retrogressive path. Brittle deformation of pyrite and growth of irregular pyritic mass around such fractured porphyroblasts characterize the waning phase of regional metamorphism. A subsequent phase of stress-free, thermal metamorphism is recorded in the decussate and rosette textures of arsenopyrite prisms replacing irregular pyritic mass. Annealing of such patchy pyrite provides information regarding the temperature conditions during this episode of thermal metamorphism which is consistent with the hornblendehornfels facies metamorphism interpreted from magnetite–ilmenite geothermometry (550°C) and sphalerite geobarometry (3.5 kbar). A mild cataclastic deformation during the penultimate phase produced microfaults in twinned arsenopyrite prisms.

scholarly journals PESTRÉ SEDIMENTY OTTNANGU V BRNĚ-KOHOUTOVICÍCH

2018 ◽  
Vol 25 (1-2) ◽  
Author(s):  
Pavla Tomanová Petrová ◽  
David Buriánek ◽  
Karel Kirchner ◽  
Oldřich Krejčí ◽  
František Laufek ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Clay Minerals ◽  
Heavy Fraction ◽  
Parent Rock ◽  
Fine Grained ◽  
Sediment Layers

The reddish coloured sediment layers (up to 5 m thick) were found within building pit in the Brno-Kohoutovice on the Libušina třída Avenue (NW part of Brno). These sediments were assigned to the Ottnangian based on characteristic pseudoassociation of microfossils. Smectite or illite/smectite dominates over kaolinite among the clay minerals. Minerals typomorphic for granitoids of the Brno Massif, i.e. epidote, amphibole and altered titanite, absolutely dominate (99 mod. %) within the assemblage of translucent heavy fraction. Minerals like garnet and staurolite which are typical for the Ottnangian sediments in this region, are presented only in accessoric amount. The chemical composition of the studied sediments is located between the chemical composition of granodiorites of the Brno Massif and Neogene clays. Relatively high content of Zr, Hf and HREE, which is interpreted as result of presence of very fine grained zircon in studied sediments, is characteristic. High content of SiO2 and comparatively low contents of Al2O3 and Fe2O3 indicates non-lateritic type of weathering. The chemical composition of studied sediments reflects semiarid to humid paleoclimate that the granitoids of the Brno Massif as parent rock have undergone.

scholarly journals The Mineralogical Composition of Samos Zeoliitic Rocks and their potential use as Feed Additives and Nutrition Supplements

2020 ◽  
Vol 56 (1) ◽  
pp. 84
Author(s):  
Anestis Filippidis ◽  
Christina Mytiglaki ◽  
Nikolaos Kantiranis ◽  
Ananias Tsirambides
Keyword(s):  
Clay Minerals ◽  
Animal Species ◽  
Mineralogical Composition ◽  
Feed Additives ◽  
Feed Additive ◽  
X Ray Diffraction ◽  
Eu Regulation ◽  
Fibrous Minerals ◽  
Potential Use ◽  
The Eu

Fifteen (15) zeolitic rocks from Karlovassi-Marathokampos basin of Samos Island (Greece) were investigated for their mineralogical composition by X-Ray Diffraction (XRD) method. According to EU Regulation No 651/2013, clinoptilolite of sedimentary origin with ≥80 wt% clinoptilolite, ≤20 wt% clay minerals, free of fibres and quartz, can be used as feed additive for all animal species. Depending on the zeolites, the zeolitic rocks are grouped to those containing: Clinoptilolite (33-86 wt%), clinoptilolite (59 wt%) + mordenite (20-21 wt%), clinoptilolite (22 wt%) + analcime (29 wt%), clinoptilolite (17 wt%) + phillipsite (27 wt%), analcime (29-70 wt%), mordenite (62%) and chabazite (63 wt%). None of the clinoptilolite-containing rocks (10 samples) meet the requirements of the EU Regulation No 651/2013, and thus cannot be used as feed additives for all animal species and consequently as nutrition supplements, since all of them contain 2-5 wt% quartz, two of them 20-21 wt% mordenite (fibrous zeolite), nine of them <80 wt% clinoptilolite (17-73 wt%) and two of them >20 wt% clay minerals (27-42 wt%). Although the EU Regulation No 651/2013 refers to clinoptilolite of sedimentary origin, using the presence or absence of quartz and fibrous minerals, none of the five mordenite, analcime and chabazite containing zeolitic rocks, can be used as feed additives and nutrition supplements, since all of them contain 2-6 wt% quartz and one of them contains 62 wt% mordenite (fibrous zeolite).

scholarly journals Tracing the Life of a Buddhist Literary Apologia: Steps in Preparation for the Study and Translation of Sokdokpa’s Thunder of Definitive Meaning

Religions ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 933
Author(s):  
James Duncan Gentry
Keyword(s):  
Tibetan Buddhism ◽  
17Th Century ◽  
Literary Works ◽  
Historical Approach ◽  
Fine Grained ◽  
History Of ◽  
Magnum Opus ◽  
Shed Light

This article discusses Buddhist apologetics in Tibet by examining the formation, revision, and reception of the most renowned literary apologia ever written in defense of the Old School of Tibetan Buddhism: Sokdokpa Lodrö Gyeltsen’s early 17th-century magnum opus the Thunder of Definitive Meaning. It reconstructs in broad strokes the history of the Thunder’s reception from the early 17th century to the present and relates this to details in different versions of the Thunder and its addendum to shed light on the process by which this work was composed and edited. By considering this work’s peculiar context of production and history of reception alongside passages it presents revealing how it was conceived and revised, this analysis aims to prepare the ground for its study and translation. In so doing, this discussion attempts to show how a broadly historical approach can work in tandem with a fine-grained philological approach to yield fresh insights into the production and reception of Buddhist literary works that have important ramifications for their understanding and translation.

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