Early Carboniferous deformation and mineralization in the Cobequid shear zone, Nova Scotia: an 40Ar/39Ar geochronology study

2004 ◽  
Vol 41 (12) ◽  
pp. 1425-1436 ◽  
Author(s):  
Georgia Pe-Piper ◽  
Peter H Reynolds ◽  
Joe Nearing ◽  
David JW Piper
Keyword(s):  
Nova Scotia ◽  
Shear Zone ◽  
Hydrothermal Alteration ◽  
Early Carboniferous ◽  
Fault Zones ◽  
Igneous Rocks ◽  
Pluton Emplacement ◽  
History Of ◽  
Temperature Shear ◽  
Age Determinations

Latest Devonian to Early Carboniferous igneous rocks along the Cobequid shear zone of central Nova Scotia record a complex history of intrusion, volcanism, deformation, and hydrothermal alteration. Twenty new 40Ar/39Ar age determinations have been made on biotite and hornblende separates from rocks that constrain these events. The mafic plutons of the Cobequid shear zone are synchronous with the previously dated granitoid plutons (363–355 ± 4 Ma), with the exception of the younger Folly Lake gabbro (355–350 ± 4 Ma). High temperature shear deformation continued along the Cobequid shear zone during this entire period of pluton emplacement. Several samples from mylonitic and hydrothermally altered rocks with dates ca. 340 Ma indicate renewed movement along the Cobequid shear zone at this time, accompanied by minor magmatism. Younger ∼330–320 Ma ages reflect final movement along the Rockland Brook fault resulting in mid-Namurian uplift of the Cobequid Highlands. Following this regional Alleghenian event, there was no significant motion on the northern faults of the Cobequid shear zone and deformation moved southward to the Cobequid fault and its continuation in the Hollow and Chedabucto fault zones. Hydrothermal alteration, probably driven by a mid-crustal gabbro heat source, was widespread along the Cobequid and Rockland Brook faults in the early Carboniferous, resulting in albitization, potassic alteration, and iron mineralization.

Isotopic age determinations on clay minerals from lavas and tuffs of the Derbyshire orefield

1972 ◽  
Vol 109 (6) ◽  
pp. 501-512 ◽  
Author(s):  
P. R. Ineson ◽  
J. G. Mitchell
Keyword(s):  
Clay Minerals ◽  
Hydrothermal Alteration ◽  
Igneous Rocks ◽  
The Other ◽  
Mineral Deposits ◽  
Isotopic Age ◽  
Hydrothermal Mineralization ◽  
Pumice Tuff ◽  
Southern Section ◽  
Age Determinations

SummaryEpisodic hydrothermal mineralization has previously been recognized in the northern section of the Pennine orefield. Igneous rocks from the southern section (the Derbyshire orefield) have yielded isotopic ages, some of which are thought to represent ages of hydrothermal metasomatism (deuteric or subsequent). In order to ascertain whether epicyclic hydrothermal events gave rise to the Derbyshire mineral deposits, samples of highly altered doleritic lava and pumice tuff were collected adjacent to areas of mineralization. Clay-mineral concentrates from 34 samples were dated by the potassium–argon method. The conclusions drawn from these analyses support a hypothesis of repeated hydrothermal alteration of the clay minerals, reflecting at least two episodes of mineralization, one about 270 m.y., the other about 235 m.y. The geo-chronological significance of these and other results is considered.

scholarly journals Controls on Barite Mineralization in a Major Intracontinental Shear Zone: Carboniferous of the Cobequid Highlands, Nova Scotia

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1413
Author(s):  
Georgia Pe-Piper ◽  
David J. W. Piper
Keyword(s):  
Nova Scotia ◽  
Shear Zone ◽  
Fault Zone ◽  
Isotope Geochemistry ◽  
Common Origin ◽  
Late Carboniferous ◽  
Brittle Deformation ◽  
The South ◽  
History Of ◽  
Fluid Interaction

Prominent veins of late Carboniferous barite, associated with fluorite and calcite, outcrop close to older granite plutons along an intracontinental shear zone that was active throughout the Carboniferous in southeastern Canada. Some barite is stratigraphically constrained to younger than 315 Ma and final mineralization is constrained by a published Rb–Sr isochron of 300 ± 6 Ma. Barite occurrences in the Carboniferous basins of central Nova Scotia, 50 km to the south, are synchronous with or post-date ankerite-siderite-magnetite-pyrolusite and Pb-Zn mineralization, which was facilitated by fluid interaction with thick evaporites. This study aims to determine controls on the distribution of barite in the shear zone, from field relationships, vein petrography and isotope geochemistry of minerals. The isotope chemistry of shear zone barite is similar to that occurring in Pb-Zn-Mn-Ba mineralization to the south, suggesting a common origin. Veins of barite, associated with fluorite, represent the youngest and regionally coolest phase of a 70 Ma history of Carboniferous mineralized veins along the Minas Fault Zone. Their prominence close to granite plutons reflects brittle deformation of the deeply-rooted granites in a complexly deforming fault zone, but the origin of abundant F remains uncertain.

Chronology of Devonian to early Carboniferous rifting and igneous activity in southern Magdalen Basin based on U-Pb (zircon) dating

2002 ◽  
Vol 39 (8) ◽  
pp. 1219-1237 ◽  
Author(s):  
Greg R Dunning ◽  
Sandra M Barr ◽  
Peter S Giles ◽  
D Colin McGregor ◽  
Georgia Pe-Piper ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Fault Zone ◽  
Middle Devonian ◽  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Igneous Activity ◽  
Age Determinations

Fifteen U–Pb (zircon) radiometric age determinations have been made on igneous rocks of Middle Devonian to Early Carboniferous age from the southern margin of the Magdalen basin in Cape Breton Island and northern mainland Nova Scotia. Volcanic rocks interbed with early rift-basin sedimentary rocks with some palynological biostratigraphy; dated intrusive rocks cut these sedimentary units. Our biostratigraphically constrained ages are in close agreement with the current Devonian time scale. Combined with previously published data, the age determinations show that igneous activity occurred in four pulses: Middle Devonian (390–385 Ma), early Late Devonian (375–370 Ma), latest Devonian to early Tournaisian (365–354 Ma), and late Tournaisian to early Visean (ca. 339 Ma). Middle Devonian (385–389 Ma) volcanic rocks are confined to the Guysborough Group. The Fisset Brook Formation (basalt and minor rhyolite) in the type area and elsewhere in Cape Breton Island and northern mainland Nova Scotia is Late Devonian (ca. 373 Ma), whereas the biostratigraphically distinct succession at Lowland Cove is younger (365 Ma). These Late Devonian rocks are synchronous with plutonism in the Cape Breton Highlands and the Meguma terrane. In the Cobequid Highlands, rhyolite of the Fountain Lake Group was synchronous with Horton Group deposition and with widespread granite plutons (362–358 Ma) emplaced during shear on the Cobequid fault zone. The overlying Diamond Brook Formation basalts are slightly younger (355 Ma). Late Tournaisian – early Visean mafic intrusions and minor basalt occur along the Cobequid – Chedabucto fault zone and in a belt from southern New Brunswick through Prince Edward Island to southwestern Cape Breton Island.

REVIEWING AND REVISING THE PROTEROZOIC HISTORY OF THE FIVE POINTS SHEAR ZONE: A MULTIPLY DEFORMED PALEOPROTEROZOIC SHEAR THAT FORMED PRIOR TO 1.67 GA

2018 ◽  
Author(s):  
Bart T. Cubrich ◽  
◽  
Kevin R. Chamberlain ◽  
Ernest M. Duebendorfer ◽  
Matt Cochrane
Keyword(s):  
Shear Zone ◽  
History Of

Hydrothermal alteration and structural mapping of the Qolqoleh-Kasnazan shear zone in Iran using remote sensing data

2021 ◽  
Vol 14 (16) ◽  
Author(s):  
Mehdi Maleki ◽  
Shojaeddin Niroomand ◽  
Ehsan Farahbakhsh ◽  
Soroush Modabberi ◽  
Hossein Ali Tajeddin
Keyword(s):  
Remote Sensing ◽  
Shear Zone ◽  
Hydrothermal Alteration ◽  
Remote Sensing Data ◽  
Structural Mapping ◽  
Sensing Data
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