U–Pb zircon and titanite ages of three Mesozoic igneous rocks south of the Thor–Odin – Pinnacles area, southern Omineca Belt, British Columbia

1991 ◽  
Vol 28 (11) ◽  
pp. 1877-1882 ◽  
Author(s):  
Sharon D. Carr
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Middle Jurassic ◽  
Igneous Rocks ◽  
Intrusive Rocks ◽  
Age Limit ◽  
Okanagan Valley

U–Pb zircon and titanite ages were obtained from three intrusive rocks near the Monashee Highway between the Valhalla complex and the Okanagan Valley in the southern Omineca Belt. Granitoid phases that have been previously grouped together and referred to as the Whatshan batholith have been subdivided on the basis of lithology and U–Pb geochronology into the Middle Jurassic Spruce Grove batholith and the Late Cretaceous Whatshan batholith. A 77 ± 0.5 Ma phase of the Whatshan places a maximum age limit on regional F3 folding in the Pinnacles area.

scholarly journals Potential for Volcanogenic Massive Sulfide Mineralization at the A6 Anomaly, North-West British Columbia, Canada: Stratigraphy, Lithogeochemistry, and Alteration Mineralogy and Chemistry

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 867
Author(s):  
Stefanie M. Brueckner ◽  
Gregory Johnson ◽  
Stephanie Wafforn ◽  
Harold Gibson ◽  
Ross Sherlock ◽  
...  
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Isotope Composition ◽  
Massive Sulfide ◽  
Igneous Rocks ◽  
Calc Alkaline ◽  
Volcanogenic Massive Sulfide ◽  
North West ◽  
Group A ◽  
Group B

The Middle Jurassic A6 Anomaly is located 30 km southeast of Eskay Creek, north-central British Columbia and consists of thick, altered felsic igneous rocks overlain by a mafic volcano-sedimentary package. Lithogeochemistry on igneous rocks, x-ray diffraction on altered felsic units, and electron probe microanalysis and secondary ion mass spectrometry on illite and quartz were applied to explore the volcanogenic massive sulfide (VMS) potential, characterize alteration, and determine fluid conditions at the A6 Anomaly. Lithogeochemistry revealed calc-alkaline rhyodacite to trachyte of predominantly FII type, tholeiitic basalts with Nb/Yb < 1.6 (i.e., Group A), and transitional to calc-alkaline basalts and andesites with Nb/Yb > 2.2 (i.e., Group B). The felsic units showed weakly to moderately phyllic alteration (quartz–illite with minor orthoclase and trace chlorite–pyrite–calcite–barite–rutile). Illite ranged in composition from illite/smectite (K = 0.5–0.69 apfu) to almost endmember illite (K = 0.69–0.8 apfu), and formed from feldspar destruction by mildly acidic, relatively low temperature, oxidized hydrothermal fluids. The average δ18O composition was 10.7 ± 3.0‰ and 13.4 ± 1.3‰ relative to Vienna Standard Mean Ocean Water for illite and quartz, respectively. Geothermometry involving illite composition and oxygen isotope composition on illite and quartz yielded average fluid temperatures of predominantly 200–250 °C. Lithogeochemical results showed that the A6 Anomaly occurred in a late-Early to Middle Jurassic evolving back-arc basin, further east then previously recognized and in which transitional to calc-alkaline units formed by crustal assimilation to enriched Mid-Ocean Ridge Basalt (EMORB) (i.e., felsic units, Group B), followed by thinning of the crust resulting in tholeiitic normalized MORB basalts (i.e., Group A) with a minor crustal component. The alteration assemblage is representative of distal footwall alteration, and metal transport in this zone was limited despite favorable temperature, pH, and redox state, indicating a metal depleted source (i.e., felsic units).

Spatially overlapping episodes of deformation, metamorphism, and magmatism in the southern Omineca Belt, southeastern British Columbia

2018 ◽  
Vol 55 (1) ◽  
pp. 84-110 ◽  
Author(s):  
Ewan Russell Webster ◽  
David R.M. Pattison
Keyword(s):  
British Columbia ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Jurassic ◽  
Canadian Cordillera ◽  
Spatial Relationships ◽  
Metamorphic Belt ◽  
Facies Metamorphism ◽  
Contact Aureoles ◽  
Greenschist Facies Metamorphism

The southeastern Omineca Belt of the Canadian Cordillera preserves a record of overlapping Barrovian and Buchan metamorphism spanning 180–50 Ma. This paper documents the timing, character, and spatial relationships that define separate domains of Middle Jurassic, Early Cretaceous, and Late Cretaceous deformation and metamorphism, and the nature of the geological interfaces that exist between them. A domain of Early Jurassic deformation (D1) and regional greenschist-facies metamorphism (M1) is cross-cut by Middle Jurassic (174–161 Ma) intrusions. Associated contact aureoles are divided into lower pressure (cordierite-dominated; ∼2.5–3.3 kbar; 1 kbar = 100 MPa) and higher pressure (staurolite-bearing; 3.5–4.2 kbar) subtypes; contact metamorphic kyanite occurs rarely in some staurolite-bearing aureoles. Jurassic structures are progressively overprinted northwards by Early Cretaceous deformation and metamorphism (D2M2), manifested in a tightening of Jurassic structures, development of more pervasive ductile fabrics, and Barrovian metamorphism. The D2M2 domain is the southerly continuation of the 600 km long Selkirk–Monashee–Cariboo metamorphic belt. Mid-Cretaceous intrusions (118–90 Ma) were emplaced throughout the D2M2 domain, the earliest of which contain D2 fabrics, but cut M2 isograds. The D2M2 domain makes a continuous, southeasterly transition into a domain of Late Cretaceous regional Barrovian metamorphism and deformation (D3M3; 94–76 Ma). The interface between these two domains is obscured by the coaxial nature of the deformation and the apparent continuity of the metamorphic zones, resulting in a complex and cryptic interface. Similarities between the D3M3 domain and the Selkirk Crest of Idaho and Washington suggest that this domain is the northerly continuation of the northward-plunging Priest River Complex.

Geochronological constraints on magmatism and polyphase deformation and metamorphism in the southern Omineca Belt, British Columbia

2017 ◽  
Vol 54 (5) ◽  
pp. 529-549 ◽  
Author(s):  
Ewan Russell Webster ◽  
David Pattison ◽  
S. Andrew DuFrane
Keyword(s):  
British Columbia ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Jurassic ◽  
Inductively Coupled Plasma ◽  
Contact Aureole ◽  
Inductively Coupled ◽  
The North ◽  
Three Samples ◽  
Geochronological Constraints

The Omineca Belt between Nelson and Creston in southeastern British Columbia was affected by overlapping pulses of Mesozoic magmatism, metamorphism, and deformation. U–Pb geochronological data from zircon and monazite were collected by laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) to constrain the timing of these events. The Porcupine Creek stock (162.3 ± 1.3 Ma) intruded across folds and fabrics associated with the earliest phase of regional deformation and metamorphism (D1M1), restricting it to the Early–Middle Jurassic. The Jurassic structures are overprinted northwards by Early Cretaceous deformation and metamorphism (D2M2). The Baldy pluton (117.8 ± 1.2 Ma) crosscuts the regional 144–134 Ma M2 isograds, yet was pervasively affected by the D2 deformation, indicating that D2 deformation outlasted M2 metamorphism but had ceased by 111 Ma, the age of an undeformed pluton. Monazite dates from a kyanite-bearing rock in the contact aureole of the Middle Jurassic Wall stock overlap with the age of the intrusion (167 Ma), indicating a contact rather than regional origin for the kyanite. In the southeast part of the study area, three samples from the regional sillimanite zone contain monazite intergrown with sillimanite that yield dates between 80 and 69 Ma, indicating an episode of Late Cretaceous (M3) Barrovian metamorphism and deformation (D3). To the north of this domain, in an area characterized by the older D2M2 deformation, a sillimanite zone schist contains two main monazite age populations, suggestive of overlapping effects of Early Cretaceous and Late Cretaceous metamorphic episodes.

40Ar/39Ar thermochronometric constraints on the tectonic evolution of the Clachnacudainn complex, southeastern British Columbia

1999 ◽  
Vol 36 (12) ◽  
pp. 1989-2006 ◽  
Author(s):  
Maurice Colpron ◽  
Raymond A Price ◽  
Douglas A Archibald
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Tectonic Evolution ◽  
Thermal Evolution ◽  
Hanging Wall ◽  
Closure Temperature ◽  
Widespread Distribution ◽  
Early Tertiary ◽  
Intrusive Rocks ◽  
Structural Levels

40Ar/39Ar thermochronometry from the Clachnacudainn complex indicates that the thermal evolution of the complex was controlled primarily by the intrusion of granitoid plutons in mid- and Late Cretaceous times. Hornblendes from the eastern part of the complex cooled below their Ar closure temperature (ca. 500°C) shortly after intrusion of the mid-Cretaceous plutons; those from the western part of the complex have latest Cretaceous cooling dates, indicating cooling of these hornblendes after intrusion of the leucogranite plutons at ca. 71 Ma. Micas from the southern Clachnacudainn complex exhibit a pattern of progressive cooling toward lower structural levels, where Late Cretaceous and younger intrusions occur. The occurrence of Late Cretaceous - Paleocene mica cooling dates in both the hanging wall and footwall of the Standfast Creek fault refutes the hypothesis that there has been significant Tertiary extensional exhumation of the Clachnacudainn complex along the Standfast Creek fault. Furthermore, the widespread distribution of Late Cretaceous - Paleocene mica cooling ages suggests that an important volume of Late Cretaceous - early Tertiary intrusive rocks must be present in the subsurface beneath the Clachnacudainn complex.

Monitoring of Drosophila suzukii (Diptera: Drosophilidae) in Okanagan Valley vineyards, British Columbia, Canada, and assessment of damage to table and wine grapes (Vitaceae)

2020 ◽  
Vol 152 (4) ◽  
pp. 415-431
Author(s):  
Susanna Acheampong ◽  
Etienne Lord ◽  
D. Thomas Lowery
Keyword(s):  
British Columbia ◽  
Weather Conditions ◽  
Wine Grape ◽  
Drosophila Suzukii ◽  
Wine Grapes ◽  
Apple Cider ◽  
Table Grapes ◽  
Soft Fruit ◽  
Grape Cultivars ◽  
Okanagan Valley

AbstractSpotted-wing drosophila, Drosophila suzukii, (Matsumura) (Diptera: Drosophilidae), has become a serious pest of soft fruit in the Okanagan Valley of British Columbia, Canada since its detection in 2009. The study was conducted to determine the distribution of D. suzukii and damage levels in grapes. Apple cider vinegar-baited traps placed in table and wine grape (Vitis vinifera Linnaeus; Vitaceae) vineyards during 2011–2013 demonstrated that D. suzukii was numerous in all sites, with earliest emergence and highest numbers recorded in 2013. Drosophila suzukii were reared from intact and damaged table grapes and damaged wine grapes collected from the field, but not from intact wine grapes. Drosophila suzukii were reared in low numbers in 2011 from intact fruit of 11 wine grape cultivars exposed artificially in the laboratory. Susceptibility of intact wine grapes under laboratory conditions in 2011 when sour rot was widespread might relate in part to undetected infections of berries due to weather conditions. Identification of Drosophila Fallén species revealed that D. suzukii comprised a small portion of the total. Our results demonstrate that healthy wine grapes in the Okanagan Valley of British Columbia are largely undamaged by D. suzukii, while certain table grape cultivars should be protected from attack.

Bridge River tephra: revised distribution and significance for detecting old carbon errors in radiocarbon dates of limnic sediments in southern British Columbia

1980 ◽  
Vol 17 (11) ◽  
pp. 1454-1461 ◽  
Author(s):  
Rolf W. Mathewes ◽  
John A. Westgate
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lacustrine Sediments ◽  
Igneous Rocks ◽  
The South ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Horseshoe Lake ◽  
Tephra Beds

Ash-grade Bridge River tephra, identified as such on the basis of shard habit, modal mineralogy, and composition of ilmenite, occurs in sedimentary cores from three lakes located to the south of the previously documented plume and necessitates a significant enlargement of the fallout area of that tephra in southwestern British Columbia.These new, more southerly occurrences are probably equivalent to the ~2350 year old Bridge River tephra, although it can be argued from the evidence at hand that the 14C dates and biotite-rich nature support relationship to a slightly earlier Bridge River event.Large differences exist in the 14C age of sediments immediately adjacent to the Bridge River tephra at these three lake sites; maximum ages of 3950 ± 170 years BP (GX-5549) and 3750 ± 210 years BP (I-10041) were obtained at Phair and Fishblue lakes, respectively, whereas the corresponding age at Horseshoe Lake is only 2685 ± 180 years BP (GX-5757). The two older dates are considered to be significantly affected by old carbon contamination for the bedrock locally consists of calcareous sedimentary rocks and the lacustrine sediments are very calcareous. The 14C date from Horseshoe Lake, which occurs in an area of igneous rocks, appears to be only slightly too old relative to the ~2350 year old Bridge River tephra.Well-dated tephra beds, therefore, can be very useful in assessing the magnitude of old carbon errors associated with radiocarbon dates based on limnic sediments. Calcareous gyttja deposits beneath Bridge River tephra within the study area exhibit old carbon errors of the order of 1350–1550 years.

Radiolarian assemblages of Middle and Late Jurassic to early Late Cretaceous (Cenomanian) ages from an olistolith record pelagic deposition within the Bornova Flysch Zone in western Turkey

2012 ◽  
Vol 183 (4) ◽  
pp. 307-318 ◽  
Author(s):  
Ugur Kagan Tekin ◽  
M. Cemal Göncüoglu ◽  
Seda Uzuncimen
Keyword(s):  
Late Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Western Turkey ◽  
Oceanic Basin ◽  
Platform Margin ◽  
Lowermost Part ◽  
Early Late ◽  
Radiolarian Assemblages

Abstract The Bornova Flysch Zone (BFZ) in NW Anatolia comprises several olistoliths or tectonic slivers, representing various parts of the Izmir-Ankara ocean. Radiolarian assemblages extracted from one of the olistoliths of the BFZ, cropping out along the Sögütlü section, to the NE Manisa city, were studied in detail. The lowermost part of the section contains latest Bajocian – early Callovian radiolarian taxa, followed by radiolarian assemblages indicating Late Jurassic to early Late Cretaceous (Cenomanian) ages. Previous studies reveal that the Izmir-Ankara oceanic basin was initially opened during late Ladinian – early Carnian. The new radiolarian data obtained from this olistolith reveals that relatively condensed, and possibly more or less continuous, pelagic sedimentation took place during the late Middle Jurassic to early Late Cretaceous in a non-volcanic oceanic basin closer to the Tauride-Anatolide platform margin.

Potassium–Argon Ages of Igneous Rocks from the Area near Hedley, Southern British Columbia

1972 ◽  
Vol 9 (12) ◽  
pp. 1632-1639 ◽  
Author(s):  
J. C. Roddick ◽  
E. Farrar ◽  
E. L. Procyshyn
Keyword(s):  
British Columbia ◽  
Igneous Rocks ◽  
Magmatic Activity ◽  
Radiometric Ages

K–Ar ages are reported for 19 samples collected from the Hedley, Okanagan, and Similkameen Complexes located in the vicinity of Hedley, British Columbia. Although the zoned nature of amphiboles collected from the Hedley Complex makes interpretation of their radiometric ages difficult, it is suggested that the Hedley Complex was intruded at least 165 m.y. ago and was a part of the same magmatic activity that gave rise to both the Okanagan and Similkameen batholithic complexes. These latter complexes yield ages ranging from 141 m.y. to 184 m.y.

Eocene age for Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia

1992 ◽  
Vol 29 (1) ◽  
pp. 3-14 ◽  
Author(s):  
G. Beaudoin ◽  
J. C. Roddick ◽  
D. F. Sangster
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Middle Eocene ◽  
Hanging Wall ◽  
Spatial Association ◽  
High Heat ◽  
Time Interval ◽  
Genetic Link ◽  
Metasedimentary Rocks ◽  
Magmatic Event

The Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia, are hosted by the Middle Jurassic Nelson batholith and surrounding Cambrian to Triassic metasedimentary rocks in the hanging wall of the transcrustal Slocan Lake Fault, Field relations indicate that mineralization is younger than the Nelson batholith and a Middle Jurassic foliation in the Ainsworth area but coeval or older than Eocene unroofing of the Valhalla metamorphic core complex in the footwall of the Slocan Lake Fault. Lamprophyre and gabbro dykes are broadly coeval with mineralization and have biotite and hornblende K–Ar ages defining a short-lived Middle Eocene alkaline magmatic event between 52 and 40 Ma. An older, Early Cretaceous alkaline magmatic event (141 – 129 Ma) is possible but incompletely documented.K–Ar and step-heating 40Ar/39Ar analyses on hydrothermal vein and alteration muscovite indicate that hydrothermal fluids were precipitating vein and replacement deposits 58–59 Ma ago. Crosscutting relationships with lamprophyre dykes indicate the Kokanee Range hydrothermal system lasted for more than 15 Ma. Eocene crustal extension resulted in a high heat flow and structures which were probably responsible for hydrothermal fluid movement and flow paths.A 100 Ma time interval is documented between batholith emplacement and spatially associated mineralization, ruling out any genetic link between the two. Similar large age differences between granite intrusion and peripheral mineralization have recently been documented for two world-sea le Ag–Pb–Zn vein districts, which suggest that spatial association between granite and Ag–Pb–Zn mineralization is not sufficient to infer a genetic link.

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