Evidence for post-1200 Ma — pre-Grenvillian supracrustal rocks in the Pinware terrane, eastern Grenville Province at Battle Harbour, LabradorThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

2011 ◽  
Vol 48 (2) ◽  
pp. 371-387 ◽  
Author(s):  
Sandra L. Kamo ◽  
Larry M. Heaman ◽  
Charles F. Gower
Keyword(s):  
Extended Period ◽  
Mafic Rock ◽  
Amphibolite Facies ◽  
Special Issue ◽  
Supracrustal Rock ◽  
Grenville Province ◽  
Crustal Level ◽  
Minor Extent ◽  
Silicate Rocks

U–Pb zircon geochronological investigations at Battle Harbour, in the Pinware terrane, eastern Grenville Province show that a cross-bedded psammitic rock from Battle Island was deposited after 1200 Ma and prior to Grenvillian orogenesis, as part of a package of psammitic, semi-pelitic and calc-silicate rocks. This represents a major finding as no previous data had indicated any supracrustal-rock deposition after ca. 1500 Ma in the interior eastern Grenville Province. The age is comparable to that obtained from supracrustal units of minor extent elsewhere in the interior Grenville Province, indicating that change in crustal level in these regions was modest during Grenvillian orogenesis. Grenvillian metamorphism at amphibolite facies occurred at 1030 ± 4 Ma, based on evidence from a concordant mafic rock within the supracrustal assemblage that is interpreted to be a sill. Grenvillian orogenesis at Battle Harbour was accompanied by abundant pegmatite injection over an extended period, as indicated by cross-cutting relationships and various states of deformation displayed by the pegmatites. An amazonite-bearing pegmatite has an age of 1024 ± 3 Ma. An even younger, cross-cutting pegmatite contains only inherited zircon grains.

scholarly journals Mapping in the Fiskefjord area, southern West Greenland

1982 ◽  
Vol 110 ◽  
pp. 55-57
Author(s):  
A.A Garde ◽  
V.R McGregor
Keyword(s):  
Granulite Facies ◽  
Amphibolite Facies ◽  
Isotopic Age ◽  
Supracrustal Rock ◽  
Granulite Facies Metamorphism ◽  
West Greenland ◽  
Facies Metamorphism ◽  
Geological Work ◽  
Age Determinations

Previous geological work on the 1:100000 map sheet 64 V.l N (fig. 15) includes published maps of smaller areas by Berthelsen (1960, 1962) and Lauerma (1964), mapping by Kryolitselskabet Øresund A/S (Bridgwater et al., 1976) and mapping by GGU geologists for the 1:500000 map sheet Frederikshåb Isblink - Søndre Strømfjord (Allaart et al., 1977, 1978). The Amltsoq and Niik gneisses and Malene supracrustal rock units south and east of Godthåbsfjord have not so far been correlated with rocks in the Fiskefjord area. Godthåbsfjord separates the granulite facies gneisses in Nordlandet from amphibolite facies Nûk gneisses on Sadelø and Bjørneøen; the granulite facies metamorphism occurred at about 2850 m.y. (Black et al., 1973), while no published isotopic age determinations from the Fiskefjord area itself are available.

scholarly journals Editorial for Special Issue “Minerals of the Southern Grenville Province”

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 252
Author(s):  
George W. Robinson ◽  
Jeffrey R. Chiarenzelli ◽  
Marian V. Lupulescu
Keyword(s):  
Mineral Species ◽  
Special Issue ◽  
Grenville Province

The southern Grenville Province is famous for both the large number of mineral localities and the diversity of the mineral species found [...]

Petrology of Mg-Mn amphibole-bearing assemblages in manganese silicate rocks of the Sausar Group, India

1988 ◽  
Vol 52 (364) ◽  
pp. 105-111 ◽  
Author(s):  
Somnath Dasgupta ◽  
P. K. Bhattacharya ◽  
G. Chattopadhyay ◽  
H. Banerjee ◽  
N. Majumdar ◽  
...  
Keyword(s):  
Present Situation ◽  
Amphibolite Facies ◽  
The Other ◽  
Bivalent Cation ◽  
Manganese Silicate ◽  
Physical Conditions ◽  
Total Absence ◽  
Other Hand ◽  
Silicate Rocks

AbstractMg-Mn amphibole (tirodite), with or without pyroxmangite in the total absence of pyroxenes and high-calcic pyroxenoids, occurs in the Mn silicate rocks of the Sausar Group, India. The rocks were metamorphosed to amphibolite facies condition (T ∼ 650°C, P ∼ 6 kbar). Tirodite-pyroxmangite pairs developed in both carbonate-free and rhodochrosite-bearing assemblages. Also tirodite coexists with either kutnahorite or manganoan calcite in the absence of pyroxmangite. Mineral reactions inferred from modal abundances and compositions of the phases indicate stabilization of the amphibole alone from a bivalent cation-bearing residual unbuffered XCO2 system with XMn < 0.3. On the other hand, tirodite-pyroxmangite pairs appeared in unbuffered low to intermediate XCO2 assemblages with XMn > 0.35. Pyroxenes and high-calcic pyroxenoids did not appear in the present situation, though they occur elsewhere in rocks with broadly similar contents of immobile components. Closely associated assemblages of diverse mineralogy suggest that the XMn and XCO2, rather than the physical conditions of metamorphism, are the decisive factors in promoting the observed phase assemblages.

TETGAR_C: a three-dimensional (3D) provenance plot and calculation tool for detrital garnets

2020 ◽  
Author(s):  
Wolfgang Knierzinger ◽  
Michael Wagreich ◽  
Eun Young Lee
Keyword(s):  
Three Dimensional ◽  
Greenschist Facies ◽  
Amphibolite Facies ◽  
Igneous Rocks ◽  
Source Rocks ◽  
Accurate Assessment ◽  
Potential Source ◽  
Metaigneous Rocks ◽  
Silicate Rocks

&lt;p&gt;We present a new interactive MATLAB-based visualization and calculation tool (TETGAR_C) for assessing the provenance of detrital garnets in a four-component (tetrahedral) plot system (almandine&amp;#8211;pyrope&amp;#8211;grossular&amp;#8211;spessartine). The chemistry of more than 2,600 garnet samples was evaluated and used to create various subfields in the tetrahedron that correspond to calc-silicate rocks, felsic igneous rocks (granites and pegmatites) as well as metasedimentary and metaigneous rocks of various metamorphic grades. These subfields act as reference structures facilitating assignments of garnet chemistries to source lithologies. An integrated function calculates whether a point is located in a subfield or not. Moreover, TETGAR_C determines the distance to the closest subfield. Compared with conventional ternary garnet discrimination diagrams, this provenance tool enables a more accurate assessment of potential source rocks by reducing the overlap of specific subfields and offering quantitative testing of garnet compositions. In particular, a much clearer distinction between garnets from greenschist-facies rocks, amphibolite-facies rocks, blueschist-facies rocks and felsic igneous rocks is achieved. Moreover, TETGAR_C enables a distinction between metaigenous and metasedimentary garnet grains. In general, metaigneous garnet tends to have higher grossular content than metasedimentary garnet formed under similar P&amp;#8211;T conditions.&lt;/p&gt;

Special Issue on the 2016 Kumamoto Earthquakes

2017 ◽  
Vol 12 (sp) ◽  
pp. 645-645
Author(s):  
Haruo Hayashi
Keyword(s):  
Urban Areas ◽  
Peer Review Process ◽  
Extended Period ◽  
Seismic Intensity ◽  
Intensity Level ◽  
Special Issue ◽  
Mountainous Regions ◽  
The 2016 Kumamoto Earthquakes ◽  
One Year ◽  
2016 Kumamoto Earthquakes

At 9:26 pm on April 14, 2016, a magnitude 6.5 earthquake struck directly beneath Kumamoto prefecture, Japan, producing a seismic intensity level (JMA) of 7 in Mashiki Town. Although the earthquake damage forecasting system in operation at the time predicted that this earthquake would cause no damage, it resulted in extensive human casualties and property damage centered in Mashiki Town. Past midnight on April 16, 28 hours after the first shock, the second and main shock hit, which recorded magnitude 7.3 and was the strongest recorded urban earthquake in Japan since 1995. The hypocenter extended from Kumamoto prefecture to Oita prefecture, cutting across the island of Kyushu. Mount Aso also saw increased volcanic activities which led to several landslides. This resulted in the collapse of the Great Aso Bridge, an important transportation point, causing the loss of human lives as well as obstruction of traffic for an extended period. Much confusion arose in the process of implementing measures in response to the earthquakes, which produced damage in urban areas as well as hilly and mountainous regions, raising many issues and prompting several new approaches. Researchers in many fields have conducted various activities at the disaster sites in the one-year period following the earthquakes, and produced significant findings in many areas. In order to make these results available to the wider global community, JDR is releasing a special issue on the 2016 Kumamoto Earthquakes with excellent papers and reports to mark their one-year anniversary. While the submitted papers to this special issue went through our regular peer review process, no publication charge was imposed so as to encourage as many submissions as possible. It is our hope that this special issue will contribute to throwing light on the 2016 Kumamoto Earthquakes in its entirety.

An application of Nd isotope mapping in structural geology: delineating an allochthonous Grenvillian terrane at North Bay, Ontario

2003 ◽  
Vol 140 (5) ◽  
pp. 539-548 ◽  
Author(s):  
A. P. DICKIN ◽  
R. H. MCNUTT
Keyword(s):  
Structural Geology ◽  
Amphibolite Facies ◽  
High Grade ◽  
Grenville Province ◽  
Nd Isotope ◽  
Bay Area ◽  
The North ◽  
Depleted Mantle ◽  
Different Types ◽  
Isotope Analyses

Fifty new Nd isotope analyses are presented from the North Bay area of the Grenville Province in Ontario. These data are used to map the extent of an allochthonous Grenvillian terrane which is an outlier of the Allochthonous Polycyclic Belt of the Grenville Province. Amphibolite facies orthogneisses from the allochthonous terrane have depleted mantle Nd model ages (TDM) below 1.8 Ga, whereas the gneisses of the structurally underlying parautochthon almost invariably have model ages above 1.8 Ga. The distribution of model ages is consistent with the distribution of distinct types of metabasic rock, used by other researchers as the criterion for recognizing rocks of the allochthonous and parautochthonous belts of the Grenville Province. The agreement between these different types of evidence demonstrates that Nd isotope mapping is a reliable and powerful tool for mapping terrane boundaries in high-grade metamorphic belts.

Crustal architecture and tectonic assembly of the Central Gneiss Belt, southwestern Grenville Province, Canada: a new interpretation

2000 ◽  
Vol 37 (2-3) ◽  
pp. 217-234 ◽  
Author(s):  
J WF Ketchum ◽  
A Davidson
Keyword(s):  
Structural Model ◽  
Hanging Wall ◽  
Mafic Rock ◽  
Grenville Province ◽  
The North ◽  
Rock Types ◽  
Structural Barrier ◽  
New Interpretation ◽  
Central Gneiss Belt ◽  
Tectonic Boundary

The Central Gneiss Belt, southwestern Grenville Province, is characterized by parautochthonous crust in the north and allochthonous lithotectonic domains in the south. Despite nearly two decades of study, the basal décollement to allochthonous domains transported from the southeast, known as the allochthon boundary thrust, has not been precisely located throughout much of the belt. Between Lake Nipissing and Georgian Bay where its surface trace is known, it separates 1.24 Ga Sudbury metadiabase in the footwall from eclogite remnants and 1.17-1.15 Ga coronitic olivine metagabbro confined to its hanging wall. On the premise that this relationship can be used to trace the allochthon boundary thrust elsewhere in the Central Gneiss Belt, we have sought to extend the known distribution of these mafic rock types, making use of field, petrographic, and geochemical criteria to identify them. New occurrences of all three mafic types are identified in a region extending from south of Lake Nipissing to western Quebec, and the mutually exclusive pattern of occurrence is maintained within this region. Structural trends and reconnaissance mapping of high-strain zones that appear to represent a structural barrier to the mafic suites suggest that the allochthon boundary thrust lies well to the north of its previously suggested location. Our preferred surface trace for it passes around the southern end of the Powassan batholith and through the town of North Bay before turning east to join up with the Lac Watson shear zone in western Quebec. This suggests that a large segment of "parautochthonous" crust lying north of, and including, the Algonquin domain is in fact allochthonous. The mutually exclusive distribution of the mafic suites points to significant separation of allochthonous and parautochthonous components prior to the Grenvillian orogeny, in accord with models of pre-Grenvillian continental rifting proposed by others. Despite a relative abundance of geological and geochronological data for the Central Gneiss Belt and a mafic rock distribution that appears to successfully locate a major tectonic boundary, we emphasize the need for additional field and laboratory work aimed at testing our structural model.

scholarly journals Early (3700 Ma) Archaean rocks of the Isua supracrustal belt and adjacent gneisses

1983 ◽  
Vol 112 ◽  
pp. 5-22
Author(s):  
A.P Nutman ◽  
D Bridgwater ◽  
E Dimroth ◽  
R.C.O Gill ◽  
M Rosing
Keyword(s):  
Amphibolite Facies ◽  
Iron Formation ◽  
Ultramafic Rocks ◽  
Banded Iron Formation ◽  
Sedimentary Structures ◽  
The North ◽  
Gneiss Complex ◽  
Supracrustal Belt ◽  
Silicate Rocks

A coherent stratigraphy is recognised in the highly deformed, amphibolite facies early Archaean Isua supracrustal belt. The supracrustal belt consists of layered rocks (in which sedimentary structures are locally preserved), ultramafic rocks and units of garbenschiefer (a massive Mg-Al rich, leucoamphibolite). The layered supracrustal rocks form two sequences, which are separated from each other tectonically. When folding is taken into account, these sequences are now less than 200 m thick. Sequence A forms most of the belt. In it there is a transition upwards from predominantly layered amphibolites with banded iron formation horizons to calc-silicate rocks, carbonates and layered felsic metasediments. Sequence B is restricted to the western edge of the eastern part of the supracrustal belt. It changes upwards from predominantly layered felsic metasediments to ferromagnesian mica schists. The supracrustal belt is regarded as a thin fragment from a thicker, more extensive volcanosedimentary pile. The early Archaean gneisses adjacent to the supracrustal belt consist of early multiphase tonalites which were first intruded by mafic dioritic dykes and then by granitic sheets. The granitic sheets were originaIly horizontal to gently inciined and form up to 40 per cent of the gneiss complex. Interdigitation of supracrustal rocks and gneisses in the Isukasia area is due to both the style of intrusion ofthe gneisses and to tectonic intercalation. Archaean basic dykes that cut the supracrustal belt and adjacent gneisses are ofseveral generations. Within and south of the supracrustal belt they are generally strongly deformed and have been recrystallised under amphibolite facies conditions; but in the north of the area they are generally better preserved. The dykes cut across several generations of structures in the supracrustal belt and the adjacent gneisses.

Introduction to a Special Issue on the New Labor Federalism

ILR Review ◽  
2021 ◽  
Vol 74 (5) ◽  
pp. 1085-1102
Author(s):  
Janice Fine ◽  
Michael Piore ◽  
Keyword(s):  
Collective Bargaining ◽  
New Deal ◽  
Labor Relations ◽  
Institutional Support ◽  
Extended Period ◽  
Labor Regulation ◽  
Special Issue ◽  
State And Local ◽  
The New Deal ◽  
Local Levels

The articles in this volume grew out of a 2018 conference organized by the Rutgers School of Management and Labor Relations and Cornell University’s ILR School to address questions regarding labor regulation at lower levels of government. During the extended period that federal reform has been blocked, enormous activity has taken place at the state and local levels in terms of both the passage of new employment laws and regulations as well as their administration and enforcement. Drawn from the larger set of papers presented at that conference, these articles focus on specific dimensions of the puzzle. This introduction paints the broader picture suggested by the conference and papers taken as a whole. The move toward federalism as a strategy, particularly as an alternative to organizing through the NLRA, while promising, is so far limited because it focuses on the substance of labor regulation exclusively, in isolation from the procedures through which work regulation is promulgated and enforced. The most likely place to look for reforms that will give the new labor federalism institutional support and stability comparable to that of the New Deal collective bargaining regime at its apogee is in their implementation and enforcement.

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