Late Paleozoic detrital history of eastern Gondwanaland: petrofacies and detrital geochronology of Permo-Carboniferous intracratonic sequences of the northwest Bengal Basin

2020 ◽  
Vol 90 (4) ◽  
pp. 389-402 ◽  
Author(s):  
Md. Iftekhar Alam ◽  
Ashraf Uddin ◽  
Willis E. Hames
Keyword(s):  
Sediment Cores ◽  
Granulite Facies ◽  
Mineral Chemistry ◽  
Dominant Mode ◽  
Heavy Minerals ◽  
Bengal Basin ◽  
Peninsular India ◽  
History Of ◽  
Age Range ◽  
Sandstone Petrography

ABSTRACT Permo-Carboniferous Gondwanan sequences have been reported from several isolated basins of Peninsular India. These siliciclastic sequences were preserved in several intracratonic basins in northwest Bangladesh. Sandstone petrography, heavy-mineral assemblages, mineral chemistry, and 40Ar/39Ar geochronology of sediment cores were used in this study to decipher the provenance history of Gondwanan sediments at two localities (Khalashpir and Barapukuria). Petrographic studies suggest that these sequences are mostly immature and poorly sorted arkosic sandstones (Khalashpir-Qt60F27L13, Barapukuria-Qt52F31L17), with compositions ranging from quartzarenite to litharenite. Among lithic fragments, sedimentary types are abundant. Heavy minerals are volumetrically rare and of low diversity in sediments of northwest Bangladesh. Garnet geochemistry indicates that metamorphic grades in the source terranes were of the amphibolite to granulite facies. Laser 40Ar/39Ar ages for single crystals of detrital muscovite from the deepest drilled Gondwanan sequences yielded the broadest age range, with a dominant mode at circa 515 Ma and lesser clusters of ages at circa 550, 570, and 600 Ma. The other two shallower samples are dominated by ages with similar single modes at circa 495–500 Ma. The oldest muscovite crystals may have been derived from the adjacent Indian craton and/or the Meghalayan craton. Younger muscovite crystals may have been contributed from the Pinjarra Orogen, formed during episodes of Neoproterozoic to early Paleozoic collision among India, Antarctica, and Australia.

Metamorphic evolution and zircon geochronology of early Proterozoic granulites in the Aravalli Mountains of northwestern India

2005 ◽  
Vol 142 (3) ◽  
pp. 287-302 ◽  
Author(s):  
A. B. ROY ◽  
ALFRED KRÖNER ◽  
P. K. BHATTACHAYA ◽  
SANJEEV RATHORE
Keyword(s):  
Granite Gneiss ◽  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Granulite Metamorphism ◽  
History Of ◽  
Single Zircon ◽  
Northwest India ◽  
Orogenic Cycle ◽  
Age Range ◽  
Rock Association

Granulites including a charnockite suite, mafic granulites, pelitic granulites, metanorite dykes and their retrograde varieties occur as discontinuous shear zone-bounded bodies within the Archaean basement comprising a granite gneiss–amphibolite–metasedimentary rock association in the central part of the Aravalli Mountains, northwest India. The entire suite, named the Sandmata Complex, preserves a complex history of tectonothermal evolution. Except for their strongly foliated margins, the granulite bodies are largely massive. Partial melting in the ‘country rocks’ led to the development of migmatite gneisses close to the contact of the granulite, a feature not as common in the rocks further away from the granulite contact. Geothermobarometry of massive granulites indicates Tmax>900°C and Pmax∼7.5 kbar. The retrograde granulites, which formed at lower amphibolite/upper greenschist-facies conditions, experienced channelized hydration reactions concomitant with shearing. These rocks locally appear as hornblende–biotite-bearing foliated granulite with or without Cpx or Opx. The rocks seem to have followed an inverse PTt path and have undergone an earlier phase of near-isobaric cooling. Our single zircon Pb–Pb ages indicate that the exhumation of granulites to the shallower amphibolite-facies levels with concomitant melting in the country rocks took place between 1690 Ma and 1621 Ma. Assuming that the granulite-facies metamorphism took place at around 1725 Ma, we relate the entire process of granulite metamorphism and exhumation covering an age range between 1725 and 1621 Ma to the rift basin opening stages of the Delhi Orogenic cycle that culminated at c. 1450 Ma.

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

Syphilis among men who have sex with men attending a large HIV clinic in Trinidad

2021 ◽  
pp. 095646242199719
Author(s):  
Robert Jeffrey Edwards ◽  
Isshad John ◽  
Selena Todd ◽  
Leon-Omari Lavia ◽  
David Musa ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Chart Review ◽  
Laboratory Data ◽  
Previous History ◽  
History Of ◽  
Review Study ◽  
Sex With Men ◽  
Associated Risk Factors ◽  
Living With Hiv ◽  
Age Range

A chart review study was conducted to determine the prevalence of syphilis and explore the associated risk factors among men who have sex with men (MSM) who attended a large HIV clinic in Trinidad during the period January–December 2019. Patients were routinely screened for syphilis annually, and demographic, clinical, and laboratory data were extracted from the medical records. Descriptive and bivariate analyses were performed, and factors significantly associated with a syphilis diagnosis were assessed using multivariate logistic regression. During the period, 218 MSM were seen, age range 19–67 years, and median age 34.0 years. The prevalence of syphilis was 41.3% (90/218), and 71.1% (64//90) of these infections were asymptomatic. Multivariate analysis using logistic regression showed that MSM living with HIV in the 30–34 years old-age group (OR, 4.32; 95% CI, 1.04–18.02), and those with a previous history of treated syphilis (OR, 10.18; 95% CI, 4.60–22.53) were more likely to be diagnosed with syphilis. The prevalence of syphilis is high among MSM attending the HIV clinic in Trinidad, and most of these infections were asymptomatic; hence, targeted and sustained interventions to reduce syphilis transmission are urgently required. Repeat episodes of syphilis may play a role in the transmission dynamics of syphilis in MSM.

The Metasomatized Mantle beneath the North Atlantic Craton: Insights from Peridotite Xenoliths of the Chidliak Kimberlite Province (NE Canada)

2019 ◽  
Vol 60 (10) ◽  
pp. 1991-2024 ◽  
Author(s):  
M G Kopylova ◽  
E Tso ◽  
F Ma ◽  
J Liu ◽  
D G Pearson
Keyword(s):  
North Atlantic ◽  
Thermal State ◽  
Mineral Chemistry ◽  
Mantle Metasomatism ◽  
Labrador Sea ◽  
The North ◽  
Rock Types ◽  
History Of ◽  
The North Atlantic ◽  
North Atlantic Craton

Abstract We studied the petrography, mineralogy, thermobarometry and whole-rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156–138 Ma Chidliak kimberlite province (Southern Baffin Island). Xenoliths from pipes CH-1, -6, -7 and -44 are divided into two garnet-bearing series, dunites–harzburgites–lherzolites and wehrlites–olivine pyroxenites. Both series show widely varying textures, from coarse to sheared, and textures of late formation of garnet and clinopyroxene. Some samples from the lherzolite series may contain spinel, whereas wehrlites may contain ilmenite. In CH-6, rare coarse samples of the lherzolite and wehrlite series were derived from P = 2·8 to 5·6 GPa, whereas predominant sheared and coarse samples of the lherzolite series coexist at P = 5·6–7·5 GPa. Kimberlites CH-1, -7, -44 sample mainly the deeper mantle, at P = 5·0–7·5 GPa, represented by coarse and sheared lherzolite and wehrlite series. The bulk of the pressure–temperature arrays defines a thermal state compatible with 35–39 mW m–2 surface heat flow, but a significant thermal disequilibrium was evident in the large isobaric thermal scatter, especially at depth, and in the low thermal gradients uncharacteristic of conduction. The whole-rock Si and Mg contents of the Chidliak xenoliths and their mineral chemistry reflect initial high levels of melt depletion typical of cratonic mantle and subsequent refertilization in Ca and Al. Unlike the more orthopyroxene-rich mantle of many other cratons, the Chidliak mantle is rich (∼83 vol%) in forsteritic olivine. We assign this to silicate–carbonate metasomatism, which triggered wehrlitization of the mantle. The Chidliak mantle resembles the Greenlandic part of the North Atlantic Craton, suggesting the former contiguous nature of their lithosphere before subsequent rifting into separate continental fragments. Another, more recent type of mantle metasomatism, which affected the Chidliak mantle, is characterized by elevated Ti in pyroxenes and garnet typical of all rock types from CH-1, -7 and -44. These metasomatic samples are largely absent from the CH-6 xenolith suite. The Ti imprint is most intense in xenoliths derived from depths equivalent to 5·5–6·5 GPa where it is associated with higher strain, the presence of sheared samples of the lherzolite series and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as tens of kilometers or as local as <1 km. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as <1 Myr, shortly predating kimberlite formation. A complex protracted metasomatic history of the North Atlantic Craton reconstructed from Chidliak xenoliths matches emplacement patterns of deep CO2-rich and Ti-rich magmatism around the Labrador Sea prior to the craton rifting. The metasomatism may have played a pivotal role in thinning the North Atlantic Craton lithosphere adjacent to the Labrador Sea from ∼240 km in the Jurassic to ∼65 km in the Paleogene.

scholarly journals Serial Observations and Mutational Analysis of an Adoptee with Family History of Hypertrophic Cardiomyopathy

2010 ◽  
Vol 2010 ◽  
pp. 1-4
Author(s):  
Bronwyn Harris ◽  
Jean P. Pfotenhauer ◽  
Cheri A. Silverstein ◽  
Larry W. Markham ◽  
Kim Schafer ◽  
...  
Keyword(s):  
Genetic Testing ◽  
Hypertrophic Cardiomyopathy ◽  
Family History ◽  
Mutational Analysis ◽  
Clinical Findings ◽  
Dominant Mode ◽  
Natural Mother ◽  
History Of ◽  
In Cis ◽  
Inherited Cardiac Disease

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disease with an autosomal dominant mode of transmission. Comprehensive genetic screening of several genes frequently found mutated in HCM is recommended for first-degree relatives of HCM patients. Genetic testing provides the means to identify those at risk of developing HCM and to institute measures to prevent sudden cardiac death (SCD). Here, we present an adoptee whose natural mother and maternal relatives were known be afflicted with HCM and SCD. The proband was followed closely from age 6 to 17 years, revealing a natural history of the progression of clinical findings associated with HCM. Genetic testing of the proband and her natural mother, who is affected by HCM, revealed that they were heterozygous for both the R719Q and T1513S variants in the cardiac beta-myosin heavy chain (MYH7) gene. The proband's ominous family history indicates that the combination of the R719Q and T1513S variantsin cismay be a “malignant” variant that imparts a poor prognosis in terms of the disease progression and SCD risk.

scholarly journals Application of a Polymerase Chain Reaction Assay for Detection of Proliferative Enteritis-Affected Swine Herds

1996 ◽  
Vol 8 (2) ◽  
pp. 181-185 ◽  
Author(s):  
Patricia K. Holyoake ◽  
Gary F. Jones ◽  
Peter R. Davies ◽  
Dennis L. Foss ◽  
Michael P. Murtaugh
Keyword(s):  
Polymerase Chain Reaction ◽  
Chain Reaction ◽  
Pcr Assay ◽  
Nursery Pigs ◽  
Clinically Normal ◽  
Source Of Infection ◽  
History Of ◽  
Polymerase Chain ◽  
Swine Herds ◽  
Age Range

A polymerase chain reaction (PCR) assay was used to confirm the presence of ileal symbiont (IS) intracellularis in 3 swine herds with a history of proliferative enteritis (PE). Two pooled fecal specimens, each comprising 5 individual stool samples, were collected from pen floors to screen for the presence of IS intracellularis and determine the age range of pigs shedding the organism. IS intracellularis was detected in the feces of clinically normal 10–25week-old grower/finisher pigs, indicating that this age range of pigs was the main source of infection for younger nursery pigs. Shedding continued without clinical disease when 10–100 g/ton of tylosin or 10 g/ton of chlortetracycline was added to the feed. PCR testing of pooled fecal samples can be used to identify groups of pigs affected with PE. The results of this study indicate that this PCR assay has the potential to accurately assess the IS intracellularis infection status of swine herds and the association of IS intracellular-is with PE and growth performance.

scholarly journals Sleep terrors antecedent is common in adolescents with migraine

2013 ◽  
Vol 71 (2) ◽  
pp. 83-86 ◽  
Author(s):  
Libânia Melo Nunes Fialho ◽  
Ricardo Silva Pinho ◽  
Jaime Lin ◽  
Thais Soares Cianciarullo Minett ◽  
Maria Sylvia de Souza Vitalle ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Sleep Disorders ◽  
Consecutive Series ◽  
Healthy Controls ◽  
Adolescent Population ◽  
Sleep Terrors ◽  
Headache Diary ◽  
History Of ◽  
Age Range

Migraines and sleep terrors (STs) are highly prevalent disorders with striking similarities. The aim of this study was to evaluate the effect of the antecedent of STs by comparing adolescents suffering from migraines with healthy controls in a large consecutive series. METHODS: All patients were subjected to a detailed headache questionnaire and were instructed to keep a headache diary during a two-month period. The age range was 10 to 19 years. The diagnosis of STs was defined according to the International Classification of Sleep Disorders. RESULTS: A total of 158 participants were evaluated. Of these participants, 50 suffered from episodic migraines (EMs), 57 had chronic migraines (CMs) and 51 were control subjects (CG). Participants who had a history of STs had significantly more migraines than participants who did not. CONCLUSIONS: Migraine is strongly associated with a history of STs in the adolescent population independent of demographics and pain intensity.

The Pikwitonei Granulite Domain, Manitoba: a giant Neoarchean high-grade terrane in the northwest Superior ProvinceThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.N. Machado, T.E. Krogh, and W. Weber are deceased.

2011 ◽  
Vol 48 (2) ◽  
pp. 205-245 ◽  
Author(s):  
L. M. Heaman ◽  
Ch. O. Böhm ◽  
N. Machado ◽  
T. E. Krogh ◽  
W. Weber ◽  
...  
Keyword(s):  
Granulite Facies ◽  
Superior Province ◽  
High Grade ◽  
Metamorphic Zircon ◽  
Special Issue ◽  
Metamorphic History ◽  
Zircon Growth ◽  
The World ◽  
Northwestern Margin ◽  
History Of

The Pikwitonei Granulite Domain located at the northwestern margin of the Superior Province is one of the largest Neoarchean high-grade terranes in the world, with well-preserved granulite metamorphic assemblages preserved in a variety of lithologies, including enderbite, opdalite, charnockite, and mafic granulite. U–Pb geochronology has been attempted to unravel the protolith ages and metamorphic history of numerous lithologies at three main localities; Natawahunan Lake, Sipiwesk Lake, and Cauchon Lake. The U–Pb age results indicate that some of the layered enderbite gneisses are Mesoarchean (3.4–3.0 Ga) and the more massive enderbites are Neoarchean. The high-grade metamorphic history of the Pikwitonei Granulite Domain is complex and multistage with at least four episodes of metamorphic zircon growth identified: (1) 2716.1 ± 3.8 Ma, (2) 2694.6 ± 0.6 Ma, (3) 2679.6 ± 0.9 Ma, and (4) 2642.5 ± 0.9 Ma. Metamorphic zircon growth during episodes 2 and 3 are interpreted to be regional in extent, corresponding to M1 amphibolite- and M2 granulite-facies events, respectively, consistent with previous field observations. The youngest metamorphic episode at 2642.5 Ma is only recognized at southern Cauchon Lake, where it coincides with granite melt production and possible development of a major northeast-trending deformation zone. The timing and multistage metamorphic history recorded in the Pikwitonei Granulite Domain is similar to most Superior Province high-grade terranes and marks a fundamental break in Archean crustal evolution worldwide at the termination of prolific global Neoarchean greenstone belt formation.

The History of Human Impacts in the Clear Lake Watershed ( California) as Deduced from Lake Sediment Cores*

1999 ◽  
Author(s):  
Douglas Nelson ◽  
Alan Heyvaert ◽  
Laurent Meillier ◽  
Jae Kim ◽  
Xiaoping Li ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Human Impacts ◽  
Sediment Cores ◽  
Clear Lake ◽  
History Of

scholarly journals OUTCOME OF CEREBRAL CONTUSIONS DUE TO TRAUMATIC BRAIN INJURY

2020 ◽  
Vol 11 (1) ◽  
pp. 39-43
Author(s):  
Zubair Ahmed Khan ◽  
Habib sultan ◽  
Amir Aziz ◽  
Shahrukh Rizvi ◽  
Tauqeer Ahmed ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Hospital Stay ◽  
Traffic Accidents ◽  
Road Traffic ◽  
Road Traffic Accidents ◽  
Male And Female ◽  
Duration Of Hospital Stay ◽  
History Of ◽  
Age Range

ABSTRACT:BACKGROUND & OBJECTIVE: To compare the results of surgically operated vs conservatively treated patients of cerebral contusions due to traumatic brain injury. METHODOLOGY: This comparative study was conducted from January 2012 to December 2014 at the department of Neurosurgery, PGMI Lahore General Hospital, Lahore. A total of 50 patients were included in this study of both gender (male and female) and in the age range of 15-65 years. In our study 20 patients were managed conservatively while other 30 patients were operated for cerebral contusions. The mode of injury in our study was road traffic accidents and history of falls. RESULTS: Out of 50 patients, there were 41 (82%) males and 09 (18%) female patients. Their age ranged from 15 - 65 years. In this study the overall mean age is 38.36 years. The maximum numbers of patients were in their third and fourth decades of life. In our study the duration of hospital stay in conservatively managed patients was longer as compared to surgically treated patients who were discharged earlier. Mortality rate in surgically managed patients having a GCS ranged between 09 to 12 was very low contrary to the conservatively managed group, similarly the rate of delayed contusion formation and edema was also low in surgically managed patients as compared to those who were managed conservatively. CONCLUSION: Surgically managed patients of cerebral contusions in traumatic brain injury has better outcome and decreased hospital stay as compared to conservatively managed patients.

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