Petrology and age of the Mechanic Settlement Pluton, Avalon terrane, southern New Brunswick

1995 ◽  
Vol 32 (12) ◽  
pp. 2147-2158 ◽  
Author(s):  
A. L. Grammatikopoulos ◽  
Sandra M. Barr ◽  
P. H. Reynolds ◽  
R. Doig
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Quartz Diorite ◽  
Southwestern Part ◽  
Magma Mingling ◽  
Northern Margin ◽  
Northeastern Part ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks ◽  
Olivine Gabbronorite

The Mechanic Settlement Pluton, located at the northern margin of the Caledonian Highlands in southern New Brunswick, is composed of rocks ranging from ultramafic (lherzolite, plagioclase-bearing lherzolite) through mafic (mainly olivine gabbronorite and gabbro) to intermediate (quartz diorite and monzodiorite). Spatial distribution of these lithologies, textural features, and geochemistry are consistent with evolution of a tholeiitic mafic parent magma by crystal fractionation processes, with some evidence for magma mingling between evolved gabbroic and quartz dioritic magmas. The dioritic rocks form most of the southwestern (upper?) part of the pluton, whereas the varied gabbroic rocks with ultramafic layers form the northeastern part. U–Pb (zircon) dating of a quartz diorite sample from the southwestern part of the pluton indicates crystallization at 557 ± 3 Ma. Amphibole and phlogopite in two lherzolite samples from the northeastern part of the pluton gave 40Ar/39Ar dates of 550 ± 5 and 539 ± 5 Ma, respectively, indicating that the pluton cooled rapidly through the closure temperature for amphibole, with subsequent slower cooling to the time of phlogopite closure. The pluton is interpreted to be the intrusive equivalent of basaltic units in the host Coldbrook Group, analogous to granitic plutons elsewhere in the Caledonian Highlands which appear to be the intrusive equivalents of felsic volcanic rocks in the group. These plutonic and volcanic rocks represent a major, short-lived (ca. 560–550 Ma), dominantly bimodal igneous event, apparently related to late Precambrian extension within the Avalon terrane of southern New Brunswick.

scholarly journals Geochemistry of Carboniferous peralkaline felsic volcanic rocks, central New Brunswick, Canada: examination of uranium potential

2010 ◽  
Vol 46 (0) ◽  
pp. 173-184 ◽  
Author(s):  
Taryn R. Gray ◽  
Jaroslav Dostal ◽  
Malcolm McLeod ◽  
Duncan Keppie ◽  
Yuanyuan Zhang
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Geochemistry and uranium-lead isotopic ages of volcanic rocks associated with Ladakh batholith, western Himalaya: Implications for petrogenesis and tectonic evolution

2020 ◽  
Author(s):  
Nongmaithem Lakhan Singh ◽  
Athokpam Krishnakanta Singh
Keyword(s):  
Oceanic Crust ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Primary Source ◽  
Western Himalaya ◽  
Mature Stage ◽  
Northern Margin ◽  
Felsic Volcanic ◽  
Compositional Diversity ◽  
Felsic Volcanic Rocks

<p>We present zircon U-Pb ages and whole-rock geochemistry along with mineral chemistry of the Khardung volcanic rocks outcropped in the northern margin of the Ladakh batholith in order to constrain their origin and tectono-magmatic history. These volcanic rocks are sandwiched between the Ladakh batholith in the south and the Shyok suture zone in the north and span a continuous compositional range from basalt to rhyolite, although mafic rocks are minor and intermediate to felsic rocks are volumetrically predominant. New zircon U-Pb dating for andesite coupled with two rhyolitic rocks yield 69.71 Ma, 62.49 Ma, and 66.55 Ma, defining the probable span of their magmatism from Late Cretaceous to Palaeogene. Based on their mineralogical and geochemical compositional diversity, the Khardung volcanic rocks are categorized as intermediate volcanic rocks (basaltic andesite-andesite) and felsic volcanic rocks (dacite-rhyolite). The intermediate volcanic rocks are marked by low SiO<sub>2</sub> (52.80-61.31 wt.%), enriched LREEs, and negative HFSEs (Nb, Ti, Zr) anomalies whereas,  felsic volcanic rocks are characterized by high SiO<sub>2</sub> (64.52-79.19 wt.%), pronounced negative Eu anomalies, enriched LREE and concave-downward HREE’s and negative HFSE’s (Nb, Ti) anomalies. Both the intermediate and felsic volcanic rocks exhibit quartz, sanidine, albite, bytownite, and diopside as their dominant mineral phases. Geochemical signatures indicate that the fractional crystallization and crustal contamination played a significant role in the evolution of the Khardung volcanic rocks and their geochemical diversity probably resulted from the partial melting of the common primary source, which had been metasomatized by variable contributions of fluids released from down going Neo-Tethyan oceanic crust. Thus, the Khardung volcanic rocks could be considered as a product of mature stage of arc magmatism during the subduction of the Neo-Tethyan oceanic crust, which occurred during Early Cretaceous to Palaeogene, prior to the main collision between the Indian and Asian plates.</p>

U–Pb zircon ages from the Lynn Lake and Rusty Lake metavolcanic belts, Manitoba: two ages of Proterozoic magmatism

1987 ◽  
Vol 24 (5) ◽  
pp. 1053-1063 ◽  
Author(s):  
D. A. Baldwin ◽  
E. C. Syme ◽  
H. V. Zwanzig ◽  
T. M. Gordon ◽  
P. A. Hunt ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Island Arc ◽  
Quartz Diorite ◽  
The North ◽  
Volcanic Sequence ◽  
Metavolcanic Rocks ◽  
Lynn Lake ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Two ages of magmatism have been determined from zircon in felsic flows and plutons in the Churchill Province of Manitoba. A rhyolite flow from the Lynn Lake metavolcanic belt has a U–Pb age of [Formula: see text], and a rhyolite flow from the adjacent Rusty Lake metavolcanic belt has an age of [Formula: see text]. Tonalite and quartz diorite from two composite plutons emplaced into the volcanic rocks at Lynn Lake have ages of [Formula: see text] and [Formula: see text], indistinguishable from the age of the Rusty Lake belt rhyolite. The arcuate domain of metavolcanic rocks that includes the Rusty Lake belt in the southeast, the Lynn Lake belt in the north, and the La Ronge belt (Saskatchewan) in the southwest has previously been considered a single structural sub-province with similar ages throughout. Our results and published U–Pb ages from Saskatchewan indicate that an older magmatism is represented by volcanic rocks in the Lynn Lake belt; a younger magmatism, by volcanic rocks in the Rusty Lake and La Ronge belts and plutons in the Lynn Lake belt. At Lynn Lake the older magmatism (1910 Ma) produced mafic, intermediate, and felsic volcanic rocks and synvolcanic plutons. The volcanic rocks are geochemically similar to Cenozoic island-arc magmatic sequences. These rocks were isoclinally folded and subsequently intruded by the 1876 Ma plutons. The younger, dominantly subaerial, volcanism (1878 Ma) at Rusty Lake was predominantly felsic, and the coeval plutons were granitoid. The distribution of ages and the 8 km thickness of the younger volcanic sequence suggest that the older rock served as basement during the younger magmatism.

Geochemistry of volcanic rocks from the Tetagouche Group, Bathurst, New Brunswick, Canada

1978 ◽  
Vol 15 (2) ◽  
pp. 207-219 ◽  
Author(s):  
R. E. S. Whitehead ◽  
W. D. Goodfellow
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Island Arc ◽  
Calc Alkaline ◽  
Middle Ordovician ◽  
Intermediate Range ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks ◽  
Tectonic Environments

The volcanic rocks of the Tetagouche Group are predominantly dacitic to rhyolitic pyroclastics and lavas; mafic alkaline and tholeiitic volcanic rocks are less abundant. Lavas representing the intermediate range (such as andesites) are uncommon.As a consequence of intense Na2O and K2O metasomatism, the mafic volcanic rocks have been classified on the basis of relatively immobile elements such as Ti, Y, Zr, Nb, Ni and Cr.By reference to volcanic suites described elsewhere for varying geologic and tectonic environments, the Tetagouche Group appears to represent two geologic environments. It is proposed that the deposition of tholeiitic and alkaline basalts accompanied the rifting associated with the opening of the Proto-Atlantic, which began during Hadrynian times. However the calc-alkaline felsic volcanic rocks were deposited on the top of the basaltic sequence along a mature island arc system that developed with the closing of the Proto-Atlantic during Middle Ordovician time.

U–Pb zircon ages for the Rice Lake area, southeastern Manitoba

1989 ◽  
Vol 26 (1) ◽  
pp. 23-30 ◽  
Author(s):  
A. Turek ◽  
R. Keller ◽  
W. R. Van Schmus ◽  
W. Weber
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Quartz Diorite ◽  
Granitic Rocks ◽  
Lake Area ◽  
The South ◽  
Metasedimentary Rocks ◽  
The North ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

The Archean Rice Lake greenstone belt in southeastern Manitoba is made up of mafic to felsic volcanic rocks and associated intrusive and metasedimentary rocks. The belt is flanked to the north by the Wanipigow River granitic complex and to the south by the Manigotagan gneissic belt. The Ross River quartz diorite pluton is intrusive into the centre of the greenstone belt. U–Pb zircon ages indicate a major volcanic and plutonic event in the area at 2730 Ma. Ages for two volcanic units of the Rice Lake Group are 2731 ± 3 and 2729 ± 3 Ma. The Ross River pluton yields an age of 2728 ± 8 Ma and the Gunnar porphyry gives an age of 2731 ± 13 Ma; both intrude rocks of the Rice Lake Group. Granitic rocks of the Wanipigow River granitic complex give ages of 2731 ± 10 and 2880 ± 9 Ma, while a post-tectonic granite in the Manigotagan gneissic belt has an age of 2663 ± 7 Ma.

A radiometric age of deformed granitic rocks in north-central New Brunswick

1977 ◽  
Vol 14 (7) ◽  
pp. 1687-1689 ◽  
Author(s):  
L. R. Fyffe ◽  
R. R. Irrinki ◽  
R. F. Cormier
Keyword(s):  
New Brunswick ◽  
Half Life ◽  
Volcanic Rocks ◽  
Granitic Rocks ◽  
North Central ◽  
Lower Ordovician ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

A Rb–Sr whole-rock isochron age of 489 ± 14 Ma based on a half-life of 5.0 × 1010 years is obtained from deformed granites in north-central New Brunswick indicating a Lower Ordovician age for these rocks. The corresponding age using a half-life of 4.88 × 1010 years is 479 ± 14 Ma. The granite is consanguineous with felsic volcanic rocks of the Tetagouche Group.

Revised stratigraphy of the Long Reach area, southern New Brunswick: evidence for major, northwestward-directed Acadian thrusting

1981 ◽  
Vol 18 (3) ◽  
pp. 646-656 ◽  
Author(s):  
S. R. McCutcheon
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Thrust Fault ◽  
Northern Boundary ◽  
Granitoid Rocks ◽  
Felsic Volcanic ◽  
Stratigraphic Succession ◽  
Felsic Volcanic Rocks

In the Long Reach area of southern New Brunswick, a new stratigraphic succession has been delineated; it consists of Precambrian (?) volcanic rocks, Cambrian sedimentary, volcanic and hypabyssal rocks, Silurian sedimentary rocks, and Devonian plus Precambrian (?) heterogeneous, granitoid rocks. The northern boundary of this succession is postulated to be a northwestward-directed thrust fault of Acadian age. Other Acadian thrust faults are interpreted in the area and major reverse movement of the same age occurred along the Belleisle Fault.Mafic and felsic volcanic rocks that were previously thought to be either Precambrian or Silurian are demonstrably part of the Lower Cambrian section. Some of the granitoid rocks intrude Silurian strata and therefore cannot be basement to the Cambrian succession. Other granitoid rocks appear to be older and may be Precambrian in age.

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