A major Aphebian–Helikian unconformity within the Central Mineral Belt of Labrador: definition of new groups and metallogenic implications

1978 ◽  
Vol 15 (12) ◽  
pp. 1954-1966 ◽  
Author(s):  
W. R. Smyth ◽  
B. E. Marten ◽  
A. B. Ryan
Keyword(s):  
Volcanic Rocks ◽  
Lava Flows ◽  
Grenville Province ◽  
Mafic Lava ◽  
Polyphase Deformation ◽  
Mineral Belt ◽  
Group A ◽  
Grenvillian Orogeny ◽  
Definition Of ◽  
Granitic Batholith

The Central Mineral Belt of Labrador consists of a belt of supracrustal rocks that occupies the northern foreland region of the Grenville Province of the Canadian Shield. Recent mapping in this belt has shown that the Proterozoic Croteau Group consists of two distinct sequences separated by an observed angular unconformity. It is therefore proposed that the name Croteau Group be abandoned and that the lower, Aphebian, marine sequence of sandstone, dolostone, slate, argillite, and mafic volcanic rocks be named the Moran Lake Group and that the upper, Helikian, continental sequence of conglomerate, tuffaceous sandstone, and a calc-alkalic volcanic assemblage be named the Bruce River Group.The Moran Lake Group underwent polyphase deformation, which has been assigned to the Hudsonian Orogeny, prior to deposition of the Bruce River Group around 1474 Ma. The Bruce River Group was intruded by a large granitic batholith, the Otter Lake Granite, for which a preliminary Rb–Sr isochron age of 1445 Ma has been obtained; this age correlates with the Elsonian magmatic event, an event well documented in northern Labrador. The Seal Lake Group, a Neohelikian (1278 Ma) sequence of quartzites, conglomerates, and intercalated mafic lava flows, was unconformably deposited upon the Bruce River Group and the Otter Lake Granite. During the Grenvillian Orogeny, the Bruce River and Seal Lake Groups were deformed together into a major easterly trending syncline. Deformation and metamorphism decrease across these groups to the north.The Bruce River Group forms part of the Labrador uranium area and hosts 14 known uranium occurrences. Occurrences are concentrated in the basal sandstones and conglomerates of the group, above the Aphebian–Helikian unconformity, and in ignimbrites and acid tuffs near the top of the group. No uranium occurrences are known from the Moran Lake Group except in fault-related fractures below the unconformity.

Geochemistry of the felsic metavolcanic rocks of the Wakeham Group: a metamorphosed peralkaline suite from the eastern Grenville Province, Quebec, Canada

1986 ◽  
Vol 23 (7) ◽  
pp. 978-984 ◽  
Author(s):  
James H. Bourne
Keyword(s):  
Incompatible Trace Element ◽  
White Mica ◽  
Low Grade ◽  
Textural Features ◽  
Chemical Analyses ◽  
Grenville Province ◽  
Metavolcanic Rocks ◽  
Group A ◽  
Grenvillian Orogeny ◽  
Acid Volcanics

The Wakeham Group is a suite of low-grade (greenschist facies) rocks located in the eastern Grenville Province. In order of volumetric importance, it consists of sandstones, acid volcanics, and gabbro dykes and sills. This report deals with the acid volcanic member of the group. Primary textural features have in large part been preserved. The minerals present include stilpnomelane, white mica, albite, titanite, and zircon. Calculations using 33 chemical analyses show that 29 of the compositions have normative corundum. The rocks would therefore appear to be predominantly peraluminous; however, incompatible trace-element data show affinities with other anorogenic, peralkaline suites. It is proposed that alkali loss, probably during the subsequent Grenvillian orogeny, imposed a peraluminous composition on originally peralkaline rocks. The Wakeham Group cannot be definitively correlated with other metavolcanic rocks found in the region.

scholarly journals Evidence of active magmatic rifting at the Ma’Alalta volcanic field (Afar, Ethiopia)

2021 ◽  
Vol 83 (6) ◽  
Author(s):  
Gianmaria Tortelli ◽  
Anna Gioncada ◽  
Carolina Pagli ◽  
Mauro Rosi ◽  
Laura De Dosso ◽  
...  
Keyword(s):  
Seismic Data ◽  
Volcanic Field ◽  
Lava Flows ◽  
Magmatic Activity ◽  
Magma Storage ◽  
Plumbing System ◽  
Mafic Lava ◽  
Cinder Cones ◽  
Mafic Rocks ◽  
Seismic Networks

AbstractDuring continental rifting, strain and magmatism are believed to localize to narrow magmatic segments, while the rift margin is progressively abandoned. We integrate volcanological, geochemical, petrological and seismic data from the Ma’Alalta volcanic field (MVF) near the western margin of Afar, to show that the MVF is an active magmatic segment. Magmatism in MVF initiated with lava flows and large-volume, caldera-forming ignimbrites from a central edifice. However, the most recent magmatic activity shifted towards mafic lava fields, cinder cones and obsidian-rich silicic domes erupted from vents aligned NNW-SSE, defining a ~ 35-km-long magmatic segment. Along the same area, a NNW-SSE alignment of earthquakes was recorded by two local seismic networks (2005–2009 and 2011–2013). The geochemistry of the mafic rocks is similar to those of nearby axial volcanoes. Inferred magma storage depth from mineral geobarometry shows that a shallow, silicic chamber existed at ~ 5-km depth below the stratovolcano, while a stacked plumbing system with at least three magma storage levels between 9 and 24 km depth fed the recent basalts. We interpret the wide set of observations from the MVF as evidence that the area is an active magmatic segment, showing that localised axial extension can be heavily offset towards the rift margin.

Geology and age of the Precambrian basement in the Windsor, Chatham, and Sarnia area, southwestern Ontario

1982 ◽  
Vol 19 (8) ◽  
pp. 1627-1634 ◽  
Author(s):  
A. Turek ◽  
R. N. Robinson
Keyword(s):  
Oil And Gas ◽  
Precambrian Basement ◽  
Grenville Province ◽  
Metasedimentary Rocks ◽  
Gas Drilling ◽  
Arch System ◽  
Grenvillian Orogeny ◽  
Anomaly Map ◽  
Paleozoic Rocks ◽  
Basement Surface

Precambrian basement in the Windsor–Chatham–Sarnia area is covered by Paleozoic rocks that are up to 1300 m thick. The basement surface is characterized by a northeast–southwest arch system with a relief of about 350 m. Extensive oil and gas drilling has penetrated and sampled this basement, and an examination of core and chip samples from 133 holes and an assessment of the magnetic anomaly map of the area have been used to produce a lithologic map of the Precambrian basement. The predominant rocks are granite gneisses and syenite gneisses but also significant are gabbros, granodiorite gneisses, and metasedimentary rocks. The average foliation dips 50° and is inferred to have a northeasterly trend. The Precambrian basement has been regarded as part of the Grenville Province. An apparent Rb–Sr whole rock isochron, for predominantly meta-igneous rocks, yields an age of 1560 ± 140 Ma. This we interpret as pre-Grenvillian, surviving the later imprint of the Grenvillian Orogeny. Points excluded from the isochron register ages of 1830, 915, and 670 Ma, and can be interpreted as geologically meaningful.

Volcanoes geological mapping and structural geology with UAS High Resolution Digital Terrain Model : the Kuei-Shan Tao case example (Eastern Taiwan).

2021 ◽  
Author(s):  
Benoit Deffontaines ◽  
Kuo-Jen Chang ◽  
Samuel Magalhaes ◽  
Gérardo Fortunato
Keyword(s):  
High Resolution ◽  
Okinawa Trough ◽  
Volcanic Rocks ◽  
Digital Terrain Model ◽  
Structural Features ◽  
Point Of View ◽  
Geological Mapping ◽  
Lava Flows ◽  
Aerial Photographs ◽  
Structural Scheme

<p>Volcanic areas in the World are often difficult to map especially in a structural point of view as (1) fault planes are generally covered and filled by more recent lava flows and (2) volcanic rocks have very few tectonic striations. Kuei-Shan Tao (11km from Ilan Plain – NE Taiwan) is a volcanic island, located at the soutwestern tip of the South Okinawa trough (SWOT). Two incompatible geological maps had been already published both lacking faults and structural features (Hsu, 1963 and Chiu et al., 2010). We propose herein not only to up-date the Kuei-Shan Tao geological map with our high resolution dataset, but also to create the Kuei-Shan Tao structural scheme in order to better understand its geological and tectonic history.</p><p>Consequently, we first acquired aerial photographs from our UAS survey and get our new UAS high resolution DTM (HR UAS-DTM hereafter) with a ground resolution <10cm processed through classical photogrammetric methods. Taking into account common sense geomorphic and structural interpretation and reasoning deduced form our HR UAS-DTM, and the outcropping lithologies situated all along the shoreline, we have up-dated the Kuei-Shan Tao geological mapping and its major structures. To conclude, the lithologies (andesitic lava flows and pyroclastic falls) and the new structural scheme lead us to propose a scenario for both the construction as well as the dismantling of Kuei-Shan Tao which are keys for both geology and geodynamics of the SWOT.</p>

scholarly journals Efficiency of road tax in the tax system of the Czech Republic

2012 ◽  
Vol 60 (2) ◽  
pp. 17-24 ◽  
Author(s):  
Břetislav Andrlík
Keyword(s):  
Czech Republic ◽  
Total Expenditure ◽  
Tax System ◽  
The Czech Republic ◽  
Administrative Costs ◽  
Average Value ◽  
Group A ◽  
Ministry Of Finance ◽  
Definition Of ◽  
Specific Number

The paper deals with the efficiency of road tax in the tax system of the Czech Republic, focusing on the administrative costs of taxation on the timeline 2005 to 2009. It contains a theoretical definition of tax efficiency, and describes the types of costs connected with taxes. From this perspective it focuses on quantifying the direct administrative costs of road tax. Direct measurement of administrative costs is done by using the method called the method of recounted worker which classifies employees of local tax authorities in separate groups and assigns each group a specific number of employees for each reference road tax using the conversion factors. Then it defines the total expenditure of local tax authorities using the coefficients for a particular monitored tax and it provides administrative costs as a percentage of road tax receipts. It can be said from obtained results that direct administrative costs of road taxes are higher, especially if the Ministry of Finance (2004) states that the average direct administrative costs of the tax system in the Czech Republic reach about 2 %. The results achieved in individual surveyed years are for road tax in relation to the reported average value of direct administrative costs of the tax system in the Czech Republic, increased on average by about 1.96 percentage point. Finally, the results of measurements indicating the proposed amendment are discussed.

Bruton tyrosine kinase inhibitors (BTKi) therapies in chronic lymphocytic leukemia (CLL): Review of multiple trials data for incidence of lymphocytosis and designation of partial response with lymphocytosis (PRL).

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e19502-e19502
Author(s):  
Jayant Narang ◽  
Christiana Caplan ◽  
Katarina Ludajic ◽  
Sambit Ray ◽  
Surabhi Bajpai ◽  
...  
Keyword(s):  
Partial Response ◽  
Kinase Inhibitors ◽  
Absolute Lymphocyte Count ◽  
Lymphocytic Leukemia ◽  
Additional Parameter ◽  
True Incidence ◽  
Overall Response ◽  
Group A ◽  
Definition Of ◽  
Group B

e19502 Background: In trials with BTKi, lymphocytosis alone may not be a sign of progression but rather treatment related redistribution of lymphocytes from tissues into the peripheral blood (Cheson et al 2012). This observation was later incorporated in iwCLL 2018 criteria. However, no clear details were provided on how to assess lymphocytosis along with other parameters to derive an overall timepoint response (OTR) in a clinical trial setting. While PRL is a response category used to assess lymphocytosis in many clinical trials, it has not been defined in iwCLL 2018. Furthermore, iwCLL 2018 defines Absolute Lymphocyte Count (ALC) progression (PD) as an increase of ALC ≥ 50% compared to baseline whereas conventionally progression is defined in comparison to nadir, which may lead to under reporting of ALC PD. Methods: Data from multiple (8) phase II/III CLL trials with BTKi (frontline and relapsed/refractory setting), were retrospectively analyzed. Subjects with a post baseline (post-BL) timepoint (TP) were analyzed for the incidence of ALC PD and an OTR designation of PRL, PD and other non-PD assessments (Stable Disease (SD), Non-PD and Unknown (UNK)). Results: We identified 1976 subjects with a total of 17134 post BL TPs. There were 1182 TPs (6%) with ALC PD. Out of these TPs with ALC PD, 497 TPs had OTR of PRL (42% TPs with ALC PD), 365 TPs (31%) were assessed as non-PD and 320 (27%) TPs were assessed as PD. 104 TPs (33%) of subjects with OTR of PD had at least one additional parameter driving PD. Thus, ALC PD is a common occurrence with BTKi and in line with the Cheson 2012 guidance, ALC PD alone should not be considered as overall progression. We propose that initial ALC PD with BTKi should not be considered a sign of progression but rather a treatment effect and should be assessed as PRL. However, PRL should only be assessed if Partial Response (PR) is achieved in at least 2 other involved iwCLL group A parameters (nodes, liver or spleen) and 1 group B parameter (hemoglobin or platelets). An initial decrease/normalization of the ALC compared to baseline with a subsequent progression compared to nadir, may be considered true progression in a setting of continued BTKi. If only one other group A parameter is involved and is PR with associated ALC PD, SD may be a more appropriate overall response than PRL. Conclusions: ALC PD and PRL are common in BTKi, but there is a need for standardization of the definition of ALC PD and its role in determination of OTR of PRL. We propose that ALC PD should be assessed by comparing ALC with nadir and not baseline. If PRL is assigned only when PR is met by other criteria along with ALC PD, PRL could be a part of determining Overall response rate (ORR) in protocols. Future prospective studies are needed to estimate the true incidence of ALC PD and its impact on ORR with BTKi as well as other agents which induce lymphocytosis.

scholarly journals A new species of Anomaloglossus (Anura: Aromobatidae) of the stepheni group with the redescription of A. baeobatrachus (Boistel and de Massary, 1999), and an amended definition of A. leopardus Ouboter and Jairam, 2012

Zootaxa ◽  
2019 ◽  
Vol 4576 (3) ◽  
pp. 439 ◽  
Author(s):  
ANTOINE FOUQUET ◽  
JEAN-PIERRE VACHER ◽  
ELODIE A. COURTOIS ◽  
CHLOÉ DESCHAMPS ◽  
PAUL OUBOTER ◽  
...  
Keyword(s):  
New Species ◽  
Taxonomic Status ◽  
Species Group ◽  
Type Locality ◽  
Advertisement Call ◽  
Nominal Species ◽  
Guiana Shield ◽  
Group A ◽  
Breeding Mode ◽  
Definition Of

Anomaloglossus is a species-rich genus of frogs endemic to the Guiana Shield that still harbors several unnamed species. Within the A. stepheni species group (which includes four valid nominal species), A. baeobatrachus has an uncertain taxonomic status, notably because the holotype was an unvouchered specimen depicted in a popular journal. Another member of this group, A. leopardus, was only superficially described, lacking information on the sex of specimens in the type series and on advertisement call. Therefore, these two taxa need clarifications in order to allow the description of the extant undescribed species. In this paper, we redescribe A. baeobatrachus based on newly collected material from the species type locality and provide information about its reproductive ecology. We also provide an amended definition of A. leopardus using newly collected material from its type locality. These two species form a clade along with a third species from the Eastern Guiana Shield, which is also described herein. The reproductive biology of A. baeobatrachus and A. stepheni is very similar. Both species have endotrophic and nidicolous tadpoles, despite being distantly related, suggesting independent evolution of this breeding mode. The new species and A. leopardus, on the other hand, have exotrophic tadpoles. 

Genetic responses in the early years of selection programmes using genetic differences between generations

1979 ◽  
Vol 28 (1) ◽  
pp. 65-77 ◽  
Author(s):  
I. R. Hopkins ◽  
J. W. James
Keyword(s):  
Age Groups ◽  
Genetic Differences ◽  
Early Years ◽  
Economic Returns ◽  
Investment Appraisal ◽  
Multi Stage ◽  
Parent Selection ◽  
Group A ◽  
Definition Of ◽  
Genetic Responses

ABSTRACTRecurrence relationships are used to relate breeding values of age-sex classes from different time periods. Their application to single-stage (progeny) and multi-stage (parent) selection is demonstrated. These relationships enable definition of the effect of age structure, initial genetic differences between age groups, and the extent to which allowances are made for these or later genetic differences between age groups. The expressions derived show that, given initial genetic differences between age groups, subsequent progeny means will fluctuate even under completely random selection. Using these means as a basis for measuring responses to selection, it is shown that there can be selective effects where selection is at random within parental age classes. A careful definition of the alternative programme is therefore important in interpreting results of selection experiments and in investment appraisal of selection programmes.These models were then used to describe economic returns from parent and progeny selection programmes and from programmes in which returns are realized in more than one age group. A further extension of the model accommodates the effects of finite population size on returns through its effects on genetic variance.By separating the (constant) within- and (fluctuating) between-group components of the selection differential within the recurrence relationships a number of computational problems are overcome.

scholarly journals Trace-Element and Pb Isotope Evidence on Extracting Sulfides from Potassic Melts beneath Longmenshan and Molabushan Volcanoes, Wudalianchi, Northeast China

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 319 ◽  
Author(s):  
Sergei Rasskazov ◽  
Yi-Min Sun ◽  
Irina Chuvashova ◽  
Tatyana Yasnygina ◽  
Chen Yang ◽  
...  
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Volcanic Field ◽  
Lava Flows ◽  
Pb Isotope ◽  
Linear Pattern ◽  
Wide Range ◽  
Mantle Sources ◽  
Isotope Evidence ◽  
Isotope Study

In the Wudalianchi volcanic field, eruptions started with low-Mg potassic lava flows 2.5–2.0 Ma ago and later changed to both low- and moderate-Mg potassic compositions. Volcanic rocks from the Molabushan and Longmenshan volcanoes record an unusually wide range of Pb abundances (from 3.7 ppm to 21 ppm relative to predominant range of 10–15 ppm). To determine the cause of these, we performed a comparative trace-element and Pb isotope study of rocks from these volcanoes and older lava flows. On a uranogenic lead diagram, older low-Mg lavas from lithospheric mantle sources plot on a secondary isochron with a slope corresponding to an age of 1.88 Ga. This contrasts with moderate-Mg volcanic rocks from the Molabushan cone, interpreted to have been derived from a recent convective mantle source, which define a flat linear pattern. Low-Mg rocks from the Molabushan flow have lead isotopic compositions that indicate mixed Gelaqiu and Molabu sources. Relative to rocks from the Molabushan cone, moderate-Mg lavas and slags from the East Longmenshan volcano have modified compositions characterized by Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, Ce/Pb, Th/Pb, and U/Pb ratios. We infer that the older Wudalianchi magmas were likely derived from a Paleoproterozoic lithospheric fragment, related to the evolved primordial mantle, and that later magmas were generated in the convecting mantle. These were influenced by segregation of small amounts of sulfides.

U–Pb age constraints on arenaceous and volcanic rocks of the Wakeham Group, eastern Grenville Province

2005 ◽  
Vol 42 (10) ◽  
pp. 1677-1697 ◽  
Author(s):  
O van Breemen ◽  
L Corriveau
Keyword(s):  
Volcanic Rocks ◽  
Detrital Zircons ◽  
Morphological Evidence ◽  
Ionization Mass ◽  
Grenville Province ◽  
Metavolcanic Rocks ◽  
Southeastern Margin ◽  
Depositional Age ◽  
Age Constraints ◽  
Group Yield

Combined sensitive high-resolution ion microprobe (SHRIMP) and thermal ionization mass spectrometry (TIMS) U–Pb zircon data from a tightly constrained stratigraphic context of the Wakeham Group provide a precise depositional age for sedimentation within this extensive basin of the Grenville Province. Metavolcanic rocks at the eastern exposure of the Wakeham Group yield ages of 1511 ± 13, 1506 ± 11, 1502 ± 9, and 1491 ± 7 Ma. A crosscutting 1493 ± 10 Ma porphyry vein marks the end of volcanism. The older two volcanic rocks rest stratigraphically above metasediments, with a 1517 ± 20 Ma maximum age of sedimentation derived from the youngest detrital zircons of an arenite. Five 1.61–1.55 Ga inherited zircons in the volcanics, reinforced by coeval inheritance in nearby plutons, indicate a Labradorian basement source to the supracrustals. The predominant arenite detrital zircons dates are in the 1.95–1.75 Ga range, however, and feature both trace element and morphological evidence for metamorphism in the source terrane. Together with zircons as old as 2.95 Ga, the detrital age spectrum is consistent with a circum-Superior provenance. The ages obtained imply that Wakeham Group volcanism and sedimentation were, at least in part, coeval with the onset of 1.52–1.46 Ga Pinwarian plutonism along the southeastern margin of Laurentia. U–Pb zircon analyses record a late Grenvillian metamorphic event around 1019 Ma. U–Pb monazite analyses from one sample yield 1010–1000 Ma ages, and the end of Grenvillian metamorphism is marked by 990 Ma U–Pb titanite ages.

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