scholarly journals The East Kemptville tin deposit, Yarmouth County, southwestern Nova Scotia: a lithogeochemical study of the wallrock metasedimentary rocks

10.4138/1851 ◽  
1992 ◽  
Vol 28 (1) ◽  
Author(s):  
Daniel J. Kontak ◽  
Jarda Dostal
Keyword(s):  
Nova Scotia ◽  
Metasedimentary Rocks ◽  
Tin Deposit

Geochemistry of the Namurian Lismore Formation, northern mainland Nova Scotia: sedimentation and tectonic activity along the southern flank of the Maritimes Basin

1999 ◽  
Vol 36 (10) ◽  
pp. 1655-1669 ◽  
Author(s):  
Jacquelyn E Stevens ◽  
J Brendan Murphy ◽  
Fred W Chandler
Keyword(s):  
Nova Scotia ◽  
Tectonic Activity ◽  
Isotopic Data ◽  
Rock Fragments ◽  
Metasedimentary Rocks ◽  
Clastic Rocks ◽  
Granitoid Rocks ◽  
Maritimes Basin ◽  
Group B ◽  
Southern Flank

Geochemical and isotopic data from the clastic rocks of the Namurian Lismore Formation in mainland Nova Scotia identify key episodes of tectonic activity during the development of the Maritimes Basin in Atlantic Canada. The Lismore Formation forms part of the Mabou Group and is an upward-coarsening 2500 m thick fluvial sequence deposited in the Merigomish sub-basin along the southern flank of the Maritimes Basin. Based on stratigraphic evidence, the Lismore Formation can be divided into upper and lower members which reflect variations in depositional environment and paleoclimate. The geochemical and isotopic data may also be subdivided into two groupings that primarily reflect varying contributions from accessory phases, clay minerals, or rock fragments. This subdivision occurs 115 m above the base of the upper member. The data from the lower grouping (group A) show an important contribution from underlying Silurian rocks, with a relatively minor contribution from Late Devonian granitoid rocks from the adjacent Cobequid Highlands and possibly metasedimentary rocks from the Meguma Terrane to the south. The data from the upper grouping (group B) reveal a more important contribution from the Cobequid Highlands granitoid rocks. This variation in geochemistry is thought to constrain the age of renewed motion and uplift along the faults along the southern flank of the Maritimes Basin and, more generally, suggests that geochemical and isotopic data of continental clastic rocks may help constrain the age of tectonic events that influence deposition of basin-fill rocks.

40Ar/39Ar dating of micas from the East Kemptville tin deposit, Yarmouth County, Nova Scotia

1985 ◽  
Vol 22 (10) ◽  
pp. 1546-1548 ◽  
Author(s):  
M. Zentilli ◽  
P. H. Reynolds
Keyword(s):  
Nova Scotia ◽  
North America ◽  
Iberian Peninsula ◽  
South Mountain Batholith ◽  
Northwest Africa ◽  
Acadian Orogeny ◽  
Tin Deposit

The East Kemptville tin deposit in Nova Scotia, the largest known tin deposit in North America, lies in a greisen zone within the Davis Lake Pluton, generally considered to be part of the Devonian South Mountain Batholith. Our dating of micas from within the deposit suggests that the greisenization process that accompanied mineralization took place about 295 ± 5 Ma ago, that is, ca. 60 Ma after the emplacement of the batholith.Hydrothermal alteration–mineralization activity in southern Nova Scotia coincided with extensive shearing and tectonism throughout the Hercynian orogen. The East Kemptville deposit appears to be approximately coeval with similar mineralization in southwest England, the Iberian peninsula, and northwest Africa and much younger than the Devonian Acadian orogeny.

Oxygen isotope evidence for the genesis of Upper Paleozoic granitoids from southwestern Nova Scotia

1980 ◽  
Vol 17 (1) ◽  
pp. 132-141 ◽  
Author(s):  
F. J. Longstaffe ◽  
T. E. Smith ◽  
K. Muehlenbachs
Keyword(s):  
Nova Scotia ◽  
Oxygen Isotope ◽  
Large Scale ◽  
The South ◽  
Metasedimentary Rocks ◽  
South Mountain Batholith ◽  
Oxygen Isotope Ratios ◽  
Upper Paleozoic ◽  
Isotope Evidence ◽  
Alteration Processes

The oxygen isotope ratios for 127 rocks and coexisting minerals from Paleozoic granitoids and clastic metasedimentary rocks of southwestern Nova Scotia have been measured. The whole-rock δ18O values for samples of the South Mountain batholith range from 10.1–12.0‰.But discrete granitoid plutons, located to the south of the South Mountain batholith, have lower δ18O values (7.8–10.4‰). Coexisting minerals from the Nova Scotia granitoids are near isotopic equilibrium, indicating that the whole-rock δ18O values primarily reflect the δ18O of the magma, rather than secondary alteration processes. The Meguma Group clastic metasedimentary rocks that host the Nova Scotia granitoids range in δ18O from 10.1–12.9‰. These clastic metasedimentary rocks show no systematic geographic variation in δ18O. The greenschist facies Meguma Group rocks that host the South Mountain batholith have similar δ18O values to the amphibolite facies equivalents located about the southern discrete plutons. Large scale isotopic exchange between the Meguma Group and the South Mountain batholith, or the southern plutons, is not evident.The relatively high δ18O values of the peraluminous South Mountain batholith (10.1–12.0‰) indicate that it formed by anatexis of 18O-rich clastic metasedimentary rocks. The southern plutons were also derived by partial melting of clastic metasedimentary rocks, but their lower δ18O values reflect exchange of the source material with a low 18O reservoir (mafic magmas?) prior to, or during anatexis.The sheared Brenton pluton is much lower in δ18O (5.0‰) than any of the other rocks, probably because of exchange with low 18O fluids during shearing.

scholarly journals Sedimentary and tectonic setting of a mass-transport slope deposit in the Halifax Group, Halifax Peninsula, Nova Scotia, Canada

2015 ◽  
Vol 51 (1) ◽  
pp. 084 ◽  
Author(s):  
John W.F. Waldron ◽  
Rebecca A. Jamieson ◽  
Hayley D. Pothier ◽  
Chris E. White
Keyword(s):  
Nova Scotia ◽  
Mass Transport ◽  
Tectonic Setting ◽  
Tectonic Deformation ◽  
Font Size ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Internal Structures ◽  
Transport Direction ◽  
Deformation Features

<p align="LEFT">Fine-grained metasedimentary rocks of the Halifax Group in southern mainland Nova Scotia can be subdivided into mappable units. In Halifax Peninsula, sulphide-rich hornfels, black slate, metasiltstone, and metasandstone of the Cunard Formation are overlain by grey metasedimentary rocks with abundant cross-laminations and local carbonate and calc-silicate concretions, assigned to the Bluestone Quarry Formation. No fossils are known from the Bluestone Quarry Formation but lithological correlatives elsewhere are Tremadocian. The Bluestone Quarry Formation is here divided into four members. The lowest (Point Pleasant member) contains thin parallel-laminated and cross-laminated <span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">metasandstone beds with Bouma T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">bcde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">and T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">cde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">structures, and thicker beds with Bouma ‘a’ divisions. The Black Rock </span></span>Beach member lacks the thicker massive beds and is dominated by rippled and cross-laminated metasedimentary rocks. The overlying Chain Rock member, an erosion-resistant ridge-forming unit, is disrupted by folds and boudinage. Bedding is truncated at the upper contact, and the internal structures are overprinted by (and therefore predate) the Neoacadian cleavage. They are interpreted as products of synsedimentary mass transport. Scarce folds in the Chain Rock member and current ripples in the underlying unit are consistent with a N or NW transport direction. The overlying Quarry Pond member consists of thinly bedded coherent metasedimentary rocks that generally resemble those of the Black Rock Beach member. Although there are indications of upward shallowing in equivalent successions elsewhere in the Halifax Group, the presence of a major mass transport deposit in the Bluestone Quarry Formation shows that this part of the Halifax Group was deposited on a submarine paleoslope. The failure of geologists to identify this feature in much-visited outcrops testifies to the difficulty of identifying synsedimentary deformation features that have been overprinted by later tectonic deformation.</p>

Occurrence, origin, and significance of melagranites in the South Mountain Batholith, Nova Scotia

2017 ◽  
Vol 54 (7) ◽  
pp. 693-713 ◽  
Author(s):  
Michael A. MacDonald ◽  
D. Barrie Clarke
Keyword(s):  
Nova Scotia ◽  
Trace Element ◽  
Alkali Feldspar ◽  
Chemical Compositions ◽  
Metasedimentary Rocks ◽  
South Mountain Batholith ◽  
Pelitic Fraction ◽  
Assimilation Process ◽  
Compositional Variations ◽  
Physical And Chemical

Melagranites (colour index > 20, with biotite > garnet > cordierite) constitute ∼0.1% of the area of the 7300 km2 peraluminous South Mountain Batholith (SMB), Nova Scotia. The melagranites occur as small bodies showing sharp to gradational contacts against the Meguma Supergroup country rocks, and coeval mingling contacts against other facies of the batholith. They also occur as elliptical or blocky metre-scale enclaves elsewhere in the SMB. Characteristic petrological features of the melagranites include high modal abundances of sulphide minerals, strongly reacted metasedimentary xenoliths, mafic mineral-rich clots, apparent porphyritic textures with highly variable proportions of alkali feldspar megacrysts, and allotriomorphic-granular textures. Chemically and isotopically, melagranite rocks have wide compositional variations. In most major-element, trace-element, and isotopic variation diagrams, the melagranites lie on mixing lines between the more abundant granodioritic and monzogranitic phases of the SMB and the metasedimentary rocks of the Meguma Supergroup. Textural evidence, supported by published experimental evidence, suggests that the garnet, cordierite, and K-feldspar are peritectic phases resulting from incongruent melting of the pelitic fraction of the Meguma metasedimentary country rocks. The field relations, mineral assemblages, textural features, and chemical compositions of the melagranites all point to the melagranites as highly concentrated contamination zones in the SMB, representing small portions of the batholith that have failed either to complete the assimilation process or to disperse their contaminants widely in the batholith. As such, these rarely preserved melagranites provide petrogenetic information disproportionate in importance to their abundance in the batholith, especially about the significant role of contamination and assimilation in determining the physical and chemical composition of the SMB. Without preservation of melagranites in the SMB, and by extension all granite bodies, the petrogenetic importance of contamination is difficult to assess, even with trace-element and isotopic data. The present study shows that high quality field observations are as important in deciphering petrogenesis as chemical data.

Granite-hosted mineral deposits of the New Ross area, South Mountain Batholith, Nova Scotia, Canada: P, T and X constraints of fluids using fluid inclusion thermometry and decrepitate analysis

2000 ◽  
Vol 91 (1-2) ◽  
pp. 303-319 ◽  
Author(s):  
Sarah Carruzzo ◽  
Daniel J. Kontak ◽  
D. Barrie Clarke
Keyword(s):  
Nova Scotia ◽  
Fluid Inclusion ◽  
Electron Microprobe ◽  
Meteoric Water ◽  
Mineral Deposits ◽  
Fluid Inclusion Data ◽  
Metasedimentary Rocks ◽  
Low Salinity ◽  
South Mountain Batholith ◽  
Highly Evolved

The 370 Ma peraluminous South Mountain Batholith (SMB) intrudes Meguma Supergroup metasedimentary rocks in Nova Scotia. The New Ross area of the SMB contains polymetallic mineralisation (Sn, W, U, Mo, Cu and Mn) in pegmatite, greisen and vein directly or indirectly associated with highly evolved fractions of the SMB. Eight mineral deposits from this area have several fluid inclusion types hosted by quartz: (1) monophase liquid (L); (2) monophase vapour (V); (3) aqueous, L-V (4) aqueous, L-rich + solids; (5) aqueous, L-rich + halite. Inclusions have irregular to equant shapes and are pseudo-secondary or secondary. The irregularity and variability of L:V ratios within fluid inclusion populations suggest post-entrapment modifications of inclusions (i.e. necking).Thermometric data indicate three distinct fluids in terms of salinity: (1) 19-25 wt. % equiv. NaCl (rarely 14-25 wt. % NaCl equiv.), (2) 29-43 wt. % equiv. NaCl, and (3) 0-9 wt. % equiv. NaCl. Temperatures of first melting and ice/hydrohalife melting indicate CaCl2 in solution. Proximity of the deposits to Meguma Supergroup metasedimentary rocks suggests that this Ca component may be externally derived. The majority of the low-salinity fluid population has the composition of meteoric water. Electron microprobe analyses of artificially decrepitated mounds identify Na, Ca and K as major solutes, with a continuum in terms of compositions. Other solute components in the mounds are Fe and Ba, and a variety of metals of unknown speciation also occur (Cu, Zn, Fe, Ni). Homogenisation temperatures (Th) range from c. 80°C to 370°C, but for inclusion assemblages the range is 10°C to 20°C. Given the 3 kbar depth of emplacement of the SMB, estimated entrapment temperatures are c. 200°C to 550°C. The fluid inclusion data appear to reflect: (1) trapping of mixed Na-K-Ca brines during isobaric cooling in pegmatite and greisen deposits as indicated by large ranges in Th; (2) formation of deposits at different ambient pressures (i.e. depth); and (3) mixing of fluids of different reservoirs (i.e. magmatic, metamorphic, meteoric).

The East Kemptville tin deposit, Yarmouth County, Nova Scotia: a Pb-isotope study of the leucogranite and mineralized greisens—evidence for a 366 Ma metallogenic event

1992 ◽  
Vol 29 (6) ◽  
pp. 1180-1196 ◽  
Author(s):  
D. J. Kontak ◽  
A. K. Chatterjee
Keyword(s):  
Nova Scotia ◽  
Isotopic Composition ◽  
Regression Line ◽  
Data Set ◽  
Rock Samples ◽  
Best Estimate ◽  
Magmatic Reservoir ◽  
Pb Isotopic Composition ◽  
Isotope Study ◽  
Tin Deposit

Pb isotopic data for whole-rock leucogranite and mineral separates, variably mineralized greisen, and galena from the East Kemptville Sn(–Cu–Zn–Ag) deposit, Yarmouth County, southwestern Nova Scotia, Canada, are presented. In contrast with ca. 300–340 Ma ages (40Ar/39Ar, Rb–Sr) previously published, an age of 366 Ma is indicated from (i) a 207Pb/206Pb slope age for whole-rock samples (leucogranite and greisen) and galena; (ii) 207Pb/206Pb slope age for leachate analyses of whole-rock and mineral separates (muscovite, K-feldspar) for a leucogranite sample (EK-161); (iii) 207Pb/206Pb slope age for all samples (leucogranite, greisen, galena) combined; and (iv) a concordia plot for 12 whole-rock samples of leucogranite and greisen. The best estimate for the time of magmatic and hydrothermal events at East Kemptville, derived by using the entire Pb–Pb data set for both mineralized and barren samples, is 366 ± 4 Ma (2σ, N = 34, mean square of weighted deviates (MSWD) = 2.63), comparable to the concordia age of 367 ± 10 Ma (2σ, N = 10, MSWD = 4.62). Isochron plots for the U–Th–Pb data may suggest mild overprinting at ca. 300 Ma, but the data are not as conclusive as results from previous Rb/Sr and 40Ar/39Ar geochronological studies.Leachate analyses of mineral separates indicate that less radiogenic compositions are obtained with each progressive leach; however, initial lead compositions are not provided by the analyses for the residues of either K-feldspar or muscovite separates. This suggests, possibly, that these minerals have reequilibrated (i.e., exchanged lead) during the subsolidus stage with fluids enriched in radiogenic Pb. Instead, the best estimate of the initial lead compositon at East Kemptville (207Pb/204Pb = 15.601, 206Pb/204Pb = 18.141) is provided by the intersection of the 366 Ma Pb–Pb regression line for a leucogranite sample (EK-161) with a second-stage growth curve having μ = 9.75; this value is less radiogenic than the average measured isotopic composition of galena (207Pb/204Pb = 15.629 ± 0.004, 206Pb/204Pb = 18.627 ± 0.005, N = 4). The calculated μ value (9.75) for the source is consistent with an evolved upper crustal reservoir. Using the calculated initial Pb composition, it is calculated that 3–5 Ma would be required to generate the measured Pb isotopic composition of the galena assuming μ values of 980 and 590, respectively. The measured day average μ value for the leucogranite and greisen is 674 (N = 12, 1σ), which is consistent with the aforementioned calculations.The coincidence of independently derived ages for both leucogranite and mineralized greisens indicates that the host muscovite–topaz leucogranite and mineralizing fluids had a common magmatic reservoir, a conclusion supported by δ18O analyses for whole-rock leucogranite (8.2–10.5‰) and greisen (7.9–10.9‰) and previously published δ34S data. The data also indicate that magmatic and hydrothermal processes at East Kemptville are coeval with emplacement of the adjacent Davis Lake pluton. In addition, the results reaffirm the 365–370 Ma period to be a significant time for Sn(–W–Mo) metallogeny within the Meguma Zone of the Canadian Appalachians.

scholarly journals Employing contact metamorphism to assess the conditions of pluton emplacement and timing of recrystallization in southwestern Kellys Mountain, Cape Breton Island, Nova Scotia

2017 ◽  
Vol 54 (11) ◽  
pp. 1165-1178 ◽  
Author(s):  
Nabil A. Shawwa ◽  
Robert P. Raeside ◽  
David W.A. McMullin ◽  
Christopher R.M. McFarlane
Keyword(s):  
Nova Scotia ◽  
Regional Metamorphism ◽  
Low Pressure ◽  
Contact Metamorphism ◽  
Contact Aureole ◽  
Low Grade ◽  
Cape Breton Island ◽  
Metasedimentary Rocks ◽  
Cape Breton ◽  
George River

At Kellys Mountain, Cape Breton Island, Nova Scotia, the late Neoproterozoic Glen Tosh formation (a low-grade metapsammite–metapelite unit of the George River Metamorphic Suite) has been intruded by diorite, granodiorite, and granite plutons, and the diorite hosts a narrow contact metamorphic aureole. New mapping and sampling in the contact aureole reveals that the metasedimentary rocks have reached amphibolite-facies metamorphism resulting in the development of neoformed biotite, muscovite, cordierite, ilmenite, garnet, andalusite, sillimanite, monazite, and spinel within the meta-pelite, a mineral assemblage also found in the Kellys Mountain Gneiss as a result of low-pressure regional metamorphism. Neoformed minerals and the disappearance of foliation defines a contact metamorphic aureole within 300 m of the pluton contacts. Petrographic and microprobe analyses of equilibrium assemblages in metapelitic units of the contact aureole yielded metamorphic pressures of 250 MPa, implying an intrusion depth of ∼9 km, with temperatures ranging from 365 to 590 °C. The presence of earlier-formed andalusite and garnet indicates the rocks may have initially undergone a low-pressure regional metamorphic event prior to contact metamorphism. Monazite in the contact aureole was dated using in-situ U–Pb methods and yielded an age of 480.9 ± 3.7 Ma, interpreted as the time of formation of the contact metamorphic aureole.

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