Metamorphosed boninitic basalts, arc tholeiites, and cryptic volcanic stratigraphy from the Elzevir Terrane of the Grenville Province, Calumet mine, Quebec

1992 ◽  
Vol 29 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Patrick J. Williams
Keyword(s):  
Alkaline Earth ◽  
Hanging Wall ◽  
Minor Element ◽  
The Other ◽  
Grenville Province ◽  
Volcanic Stratigraphy ◽  
Element Chemistry ◽  
Discrete Interval ◽  
Peak Metamorphism ◽  
Primary Structures

Amphibolites (hornblende–plagioclase rocks with Tpeak metamorphism = 650–700 °C) are abundant near the old Calumet Zn–Pb–Ag mine and Au prospect 90 km northwest of Ottawa. They lack primary structures and their original petrochemical character is obscured by metamorphism and profound alteration manifested by a variety of phlogopite–biotite-, garnet-, cummingtonite-, gahnite-, clinopyroxene-, carbonate scapolite-, and calcite-bearing assemblages. This alteration has modified the SiO2, alkali, and most alkaline earth distributions. Trace and minor element chemistry demonstrates that the amphibolites are metaigneous and bimodal, with two suites, one derived from differentiated arc tholeiites and the other from relatively undifferentiated rocks having transitional arc basalt – boninite chemistry. The complex rock package enclosing mineralization includes metatholeiites, whereas the boninitic metabasalts occur in a discrete interval in the structural hanging wall of the mineralization. Although these rocks represent a new geochemical assemblage in the Allochthonous Monocyclic Belt (Central Metasedimentary Belt), their implied geotectonic setting is comparable to those previously inferred for several other areas, including that near Montauban, Quebec, where there are very similar styles of mineralization.

scholarly journals The spectrum of beryllium fluoride

1922 ◽  
Vol 101 (709) ◽  
pp. 187-194 ◽  
Keyword(s):  
Special Reference ◽  
Homologous Series ◽  
Alkaline Earth ◽  
The Other ◽  
Empirical Equations ◽  
Molecular Weights ◽  
Beryllium Fluoride ◽  
Previous Communication

In a previous communication, an account was given of an investigation of the spectra of the fluorides of magnesium, calcium, strontium, and barium, which was undertaken with a view to determine the numerical relations existing between these spectra. It was shown that the homologous series of the different spectra can be connected by empirical equations, involving only the constants of the series equations and the molecular weights or the molecular numbers of the respective compounds. It therefore seemed desirable to extend the investigation in order to ascertain if these relations are maintained in the spectrum of beryllium fluoride. Unlike the other alkaline earth compounds, the spectra of compounds of beryllium have previously received but little attention, and it has even remained doubtful whether the well-known groups of bands between λ4426 and λ5446 belong to the element itself or to the oxide. The present investigation has special reference to the spectrum of beryllium fluoride, which has not previously been recorded.

New insights into the geologic evolution of the Grenvillian Trenton Prong inlier, Central Appalachian Piedmont, USA

2020 ◽  
Vol 57 (7) ◽  
pp. 840-854
Author(s):  
Richard A. Volkert
Keyword(s):  
Tectonic Setting ◽  
Hanging Wall ◽  
Sediment Source ◽  
Slow Cooling ◽  
Grenville Province ◽  
Magmatic Arc ◽  
Metamorphic History ◽  
Arc Setting ◽  
Appalachian Piedmont ◽  
Back Arc

New geochemical and 40Ar/39Ar hornblende and biotite data from the Grenvillian Trenton Prong inlier provide the first constraints for the identification of lithotectonic units, their tectonic setting, and their metamorphic to post-metamorphic history. Gneissic tonalite, diorite, and gabbro compose the Colonial Lake Suite magmatic arc that developed along eastern Laurentia prior to 1.2 Ga. Spatially associated low- and high-TiO2 amphibolites were formed from island-arc basalt proximal to the arc front and mid-ocean ridge basalt-like basalt in a back-arc setting, respectively. Supracrustal paragneisses include meta-arkose derived from a continental sediment source of Laurentian affinity and metagraywacke and metapelite from an arc-like sediment source deposited in a back-arc basin, inboard of the Colonial Lake arc. The Assunpink Creek Granite was emplaced post-tectonically as small bodies of peraluminous syenogranite produced through partial melting of a subduction-modified felsic crustal source. Prograde mineral assemblages reached granulite- to amphibolite-facies metamorphic conditions during the Ottawan phase of the Grenvillian Orogeny. Hornblende 40Ar/39Ar ages of 935–923 Ma and a biotite age of 868 Ma record slow cooling in the northern part of the inlier following the metamorphic peak. Elsewhere in the inlier, biotite 40Ar/39Ar ages of 440 Ma and 377–341 Ma record partial to complete thermal resetting or new growth during the Taconian and Acadian orogens. The results of this study are consistent with the Trenton Prong being the down-dropped continuation of the Grenvillian New Jersey Highlands on the hanging wall of a major detachment fault. The Trenton Prong therefore correlates to other central and northern Appalachian Grenvillian inliers and to parts of the Grenville Province proper.

The control of preexisting faults on the distribution, morphology, and volume of monogenetic volcanism in the Michoacán-Guanajuato Volcanic Field

2020 ◽  
Vol 132 (11-12) ◽  
pp. 2455-2474 ◽  
Author(s):  
Martha Gabriela Gómez-Vasconcelos ◽  
José Luis Macías ◽  
Denis Ramón Avellán ◽  
Giovanni Sosa-Ceballos ◽  
Víctor Hugo Garduño-Monroy ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Temporal Distribution ◽  
Volcanic Field ◽  
Fault System ◽  
Volcanic Stratigraphy ◽  
Listric Fault ◽  
Tectonic Processes ◽  
State Of Stress ◽  
Geological Map ◽  
Scoria Cones

Abstract Interactions between volcanic and tectonic processes affect the distribution, morphology, and volume of eruptive products in space and time. The Queréndaro area in the eastern Michoacán-Guanajuato Volcanic Field affords an exceptional opportunity to understand these relationships. Here, a Pleistocene lava plateau and 20 monogenetic volcanoes are vented from an active ENE-striking segment of the Morelia-Acambay fault system. Thirteen scoria cones are aligned along this structure, vented from an extensional gap in between two rotated hanging wall blocks of a listric fault. A new geological map, volcanic stratigraphy, and 40Ar/39Ar dating indicate that this lava plateau and volcanic cluster were emplaced from 0.81 to 0.25 Ma by 11 intermittent eruptive epochs separated by ca. 0.05 Ma, emplacing a total magma volume of 5 km3. Petrography and chemistry of rocks suggest that all volcanic structures were fed by three different magma batches but vented from independent feeder dikes. Our results indicate that preexisting faults exert a strong influence on volcanic spatial and temporal distribution, volcanic morphology, magma volume, and eruptive dynamics in this area. ENE-breached and ENE-elongated scoria cones indicate parallel subsurface fissure and feeder dikes. Additionally, points of maximum fault dilation at depth related to a transtensive state of stress coincide with less fragmented deposits and larger magma volumes. Furthermore, this study raises important questions on the geodynamics of volcano-tectonic interactions possible in similar monogenetic volcanic alignments worldwide.

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds

1999 ◽  
Vol 55 (2) ◽  
pp. 139-146 ◽  
Author(s):  
V. A. Blatov ◽  
L. V. Pogildyakova ◽  
V. N. Serezhkin
Keyword(s):  
Crystal Structure ◽  
Alkaline Earth ◽  
Organometallic Compounds ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Crystal Chemical ◽  
Coordination Polyhedra ◽  
Coordination Numbers ◽  
Coordination Spheres

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi–Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO n coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M—O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M—O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN \ge 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

Ionization of alkaline earth additives in hydrogen flames - I. Hydrogen atom concentrations and ion stabilities

1974 ◽  
Vol 338 (1613) ◽  
pp. 155-173 ◽  
Keyword(s):  
Alkaline Earth ◽  
Molecular Ions ◽  
The Other ◽  
Hydrogen Atoms ◽  
Ion Hydration ◽  
Atomic Ions ◽  
Charged Species ◽  
Hydration Energies ◽  
Three Body ◽  
Species Being

The ions present in flames of H 2 +O 2 + N 2 with trace quantities of an alkaline earth M ( = Ca or Sr) added to them have been studied mass spectrometrieally. Those detected were principally MOH + and M + , the only negatively charged species being the free electron. It was established that the reaction M + +H 2 O = MOH + +H was rapid enough to be balanced everywhere in a flame. Detailed studies of (I) provided a means for measuring the concentration of hydrogen atoms at the point of sampling in the flame from observations of [M + ]/[MOH + ]. It proved possible to make absolute determinations of [H]. In addition, the ionization potentials of CaOH and SrOH were measured as 5.7 ± 0.3 and 5.4 ± 0.3 eV, which values are slightly less than those for the corresponding alkaline earth atoms. Hydrates of MOH + and M + were observed, but it was concluded that ion-hydration is not an important flame process in this case, but rather one associated with cooling of gases as they are sampled into the mass spectrometer. It appears that molecular ions hydrate in a two-body process, e. g. MOH + + H 2 O → MOH + . H 2 O with a velocity constant, which is independent of temperature and approximately 1 x 10 –10 ml molecule –1 s –1 . Atomic ions on the other hand initially undergo hydration by a slower three-body step requiring a chaperon molecule. The first hydration energies at absolute zero for CaOH + and SrOH + were measured to be 120±20 and 109±15 kJ mol –1 respectively. These exceed the corresponding quantities for Ca + and Sr + , which were found to be 75±16 and 60±16 kJ mol –1 .

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.

Seismic structure of the Central Metasedimentary Belt, southern Grenville Province

1994 ◽  
Vol 31 (2) ◽  
pp. 243-254 ◽  
Author(s):  
C. A. Zelt ◽  
D. A. Forsyth ◽  
B. Milkereit ◽  
D. J. White ◽  
I. Asudeh ◽  
...  
Keyword(s):  
Seismic Data ◽  
High Velocity ◽  
Hanging Wall ◽  
New York State ◽  
Lake Ontario ◽  
Wide Angle ◽  
Seismic Structure ◽  
Lateral Velocity ◽  
Crust And Upper Mantle ◽  
Grenville Province

Crust and upper-mantle structure interpreted from wide-angle seismic data along a 260 km profile across the Central Metasedimentary Belt of the southern Grenville Province in Ontario and New York State shows (i) relatively high average crustal and uppermost mantle velocities of 6.8 and 8.3 km/s, respectively; (ii) east-dipping reflectors extending to 24 km depth in the Central Metasedimentary Belt; (iii) weak lateral velocity variations beneath 5 km; (iv) a mid-crustal boundary at 27 km depth; and (v) a depth to Moho of 43–46 km. The wide-angle model is generally consistent with the vertical-incidence reflectivity of an intersecting Lithoprobe reflection line. The mid-crustal boundary correlates with a crustal detachment zone in the Lithoprobe data and the depth extent of east-dipping wide-angle reflectors. Regional structure and aeromagnetic anomaly trends support the southwest continuity of Grenville terranes and their boundaries from the wide-angle profile to two reflection lines in Lake Ontario. A zone of wide-angle reflectors with an average apparent eastward dip of 13° has a surface projection that correlates spatially with the boundary between the Elzevir and Frontenac terranes of the Central Metasedimentary Belt and resembles reflection images of a crustal-scale shear zone beneath Lake Ontario. A high-velocity upper-crustal anomaly beneath the Elzevir–Frontenac boundary zone is positioned in the hanging wall associated with the concentrated zone of wide-angle reflectors. The high-velocity anomaly is coincident with a gravity high and increased metamorphic grade, suggesting northwest transport of mid-crustal rocks by thrust faulting consistent with the mapped geology. The seismic data suggest (i) a reflective, crustal-scale structure has accommodated northwest-directed tectonic transport within the Central Metasedimentary Belt; (ii) this structure continues southwest from the exposed Central Metasedimentary Belt to at least southern Lake Ontario; and (iii) crustal reflectivity and complexity within the eastern Central Metasedimentary Belt is similar to that observed at the Grenville Front and the western Central Metasedimentary Belt boundary.

scholarly journals The Timing of Metamorphism, Magmatism, and Cooling in the Zanskar, Garhwal, and Nepal Himalaya

1995 ◽  
Vol 11 ◽  
Author(s):  
M. P. Searle
Keyword(s):  
Hanging Wall ◽  
Crustal Thickening ◽  
Indian Plate ◽  
Eastern Himalaya ◽  
Normal Faults ◽  
The Tibetan Plateau ◽  
Main Central Thrust ◽  
Southern Tibet ◽  
Peak Metamorphism ◽  
Exhumation Rates

Following India-Asia collision, which is estimated at ca. 54-50 Ma in the Ladakh-southern Tibet area, crustal thickening and timing of peak metamorphism may have been diachronous both along the Himalaya (pre-40 Ma north Pakistan; pre-31 Ma Zanskar; pre-20 Ma east Kashmir, west Garhwal; 11-4 Ma Nanga Parbat) and cross the strike of the High Himalaya, propagating S (in Zanskar SW) with time. Thrusting along the base of the High Himalayan slab (Main Central Thrust active 21-19 Ma) was synchronous with N-S (in Zanskar NE-SW) extension along the top of the slab (South Tibet Detachment Zone). Kyanite and sillimanite gneisses in the footwall formed at pressure of 8-10 kbars and depths of burial of 28-35 km, 30- 21 Ma ago, whereas anchimetamorphic sediments along the hanging wall have never been buried below ca. 5-6 km. Peak temperatures may have reached 750 on the prograde part of the P-T path. Thermobarometers can be used to constrain depths of burial assuming a continental geothermal gradient of 28-30 °C/km and a lithostatic gradient of around 3.5-3.7 km/kbar (or 0.285 kbars/km). Timing of peak metamorphism cannot yet be constrained accurately. However, we can infer cooling histories derived from thermochronometers using radiogenic isotopic systems, and thereby exhumation rates. This paper reviews all the reliable geochronological data and infers cooling histories for the Himalayan zone in Zanskar, Garhwal, and Nepal. Exhumation rates have been far greater in the High Himalayan Zone (1.4-2.1 mm/year) and southern Karakoram (1.2-1.6 mm/year) than along the zone of collision (Indus suture) or along the north Indian plate margin. The High Himalayan leucogranites span 26-14 Ma in the central Himalaya, and anatexis occurred at 21-19 Ma in Zanskar, approximately 30 Ma after the collision. The cooling histories show that significant crustal thickening, widespread metamorphism, erosion and exhumation (and therefore, possibly significant topographic elevation) occurred during the early Miocene along the central and eastern Himalaya, before the strengthening of the Indian monsoon at ca. 8 Ma, before the major change in climate and vegetation, and before the onset of E-W extension on the Tibetan plateau. Exhumation, therefore, was primarily controlled by active thrusts and normal faults, not by external factors such as climate change.

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