Dejan Milidragovic

Natural Resources Canada | NRCan · Geological Survey of Canada

Although terrestrial picritic magmas with FeOTOT ⩾13 wt.% are rare in the geological record, they were relatively common ca. 2.7 Ga during the Neoarchean episode of enhanced global growth of continental crust. Recent evidence that ferropicritic underplating played an important role in the ca. 2.74–2.70 Ga reworking of the Ungava craton provides the...

Primitive, near-primary arc magmas occur as a volumetrically minor ≤100 m thick unit in the Canadian Cordillera of northwestern British Columbia, Canada. These primitive magmas formed an olivine-phyric, picritic tuff near the base of the Middle-Late Triassic Stuhini Group of the Stikine Terrane (Stikinia). A new ⁴⁰Ar/³⁹Ar age on hornblende from a c...

Upper Paleozoic to Lower Jurassic deformed rocks of the Cache Creek terrane in the Decar area, central British Columbia, include a central region of variably serpentinized or carbonate-altered ultramafic rocks (Trembleur ultramafite) that is bounded to the northeast and southwest by greenschist facies- to amphibolite facies volcano sedimentary rock...

The Early Jurassic Polaris Alaskan-type intrusion in the Quesnel accreted arc terrane of the North American Cordillera is a zoned, mafic-ultramafic intrusive body that contains two main styles of magmatic mineralization of petrologic and potential economic significance: (1) chromitite-associated platinum group element (PGE) mineralization hosted by...

The Cordillera of Canada and Alaska is a type example of an accretionary orogen, but the origin of some terranes remains contentious (e.g., Stikinia of British Columbia and Yukon, Canada). Presented herein are igneous and detrital zircon U/Pb-Hf and trace-element data, as well as the first radiolarian ages from the Asitka Group, the basement to eas...

Recommended citation: Ootes, L., Ferri, F., Milidragovic, D., and Wall, C., 2022. The age and provenance of the Lay Range assemblage provides an indirect record of basement to north-central Quesnellia, British Columbia. In: Geological Fieldwork 2021, British Columbia Ministry of Energy, Mines and Low Carbon Innovation, British Columbia Geological S...

Please see the following report that provides context for the Open File 2022-02 map: Mihalynuk, M.G., Zagorevski, A., Milidragovic, D., Tsekhmistrenko, M., Friedman, R.M., Joyce, N., Camacho, A., and Golding, M., 2018.Geologic and geochronologic update of the Turtle Lake area, NTS 104M/16, northwest British Columbia. In: Geological Fieldwork 2017,...

The Turtle Lake map area straddles the boundary between exotic, oceanic crustal and mantle rocks of the Cache Creek terrane, and Laberge Group (Early Jurassic) Whitehorse trough forearc strata atop the Stikine terrane. Exposed in the Turtle Lake area are extensive platformal carbonate rocks of the Horsefeed Formation, a regional hallmark of the C...

Ophiolite complexes are an important component of oceanic terranes in the northern Cordillera during Cordilleran orogenesis. Despite their tectonic importance, few systematic studies of these complexes have been conducted. Detailed studies of the pseudostratigraphy, age, geochemistry, and structural setting of ophiolitic rocks in the northern Cor...

The Tulameen intrusion (Late Triassic), an 18 by 6 km ultramafic-mafic body in the Quesnel terrane of southern British Columbia, is hosted by metavolcanic and metasedimentary rocks of the Nicola Group (Upper Triassic). The intrusion is zoned, with a dunite core passing outwards through olivine clinopyroxenite and clinopyroxenite, to hornblende clinop...

Supporting data for the Hogem bedrock mapping project, BC Geological Survey

British Columbia contains extensive volumes of ultramafic rock that can sequester carbon dioxide (CO2) into solid magnesium carbonate minerals to mitigate greenhouse gas (GHG) emissions. Serpentinites, altered hydrated ultramafic rocks, are of particular interest because they can be highly reactive to carbon dioxide at Earth’s surface conditions. S...

New bedrock mapping refi nes the distribution and relationships of plutonic rocks in northern Hogem batholith and surrounding rocks in the Quesnel, Stikine, and Cache Creek terranes. Cutting the Quesnel terrane, the Hogem batholith is composed of ca. 197 Ma hornblendite and diorite of the Thane Creek suite, 182 to 178 Ma biotite pyroxenite and syen...

Bedrock geology map of northern Hogem batholith, 1:50,000 scale

Serpentinization of ultramafic rocks can produce alteration minerals such as brucite (Mg(OH) 2), which has the potential to sequester carbon dioxide, and awaruite (Ni3Fe), a potential source of nickel. The Trembleur ultramafite is part of a dismembered ophiolite in central British Columbia. Field and petrographic data indicate that it is heterogene...

Ultramafic rocks commonly host Ni ± Cu-PGE mineralization and can additionally be used to sequester CO2 through mineral carbonation. In general, highly serpentinized rocks have the highest fraction of labile Mg for carbonation at ‘ambient’ earth surface conditions. Serpentinization and carbonation result in detectable changes in the physical proper...

Fieldwork overview from northern Hogem batholith, Quesnel terrane, BC

The Hart River sills are a set of mafic to intermediate intrusions that occur in northern Yukon, Canada. The largest sills are over 500 m thick and over 200 km long. New U-Pb dates of 1382.15 ± 0.39 Ma and 1382.14 ± 0.36 Ma were obtained via chemical abrasion thermal ionization mass spectrometry on zircon. Whole rock initial neodymium isotopic comp...

Rare occurrences of olivine-phyric picritic magma (MgO >12 wt. %) in arc settings are understudied, despite carrying relatively direct information about their arc mantle sources, including thermal structure, residual mineralogy, history of depletion and metasomatic enrichment, and transfer of elements to the mantle wedge at the slab-mantle interfac...

The Turtle Lake map area straddles the boundary between exotic, oceanic crustal and mantle rocks of the Cache Creek terrane, and Laberge Group (Early Jurassic) Whitehorse trough forearc strata atop the Stikine terrane. Exposed in the Turtle Lake area are extensive platformal carbonate rocks of the Horsefeed Formation, a regional hallmark of the Cac...

Upper Paleozoic to Lower Jurassic deformed rocks of the Cache Creek terrane in the Decar area, central British Columbia, include partly to completely serpentinized or carbonate-altered mantle tectonite (Trembleur ultramafite), flanked on both sides by predominantly argillaceous and siliceous fine-grained sedimentary rocks and aphanitic mafic volcan...

Island arc volcanics record interaction between the “baseline” asthenospheric arc mantle and melts and fluids derived from subducted oceanic sediments, crust, and mantle. Contributions from sub-arc lithospheric mantle, which may be genetically unrelated to the ongoing arc process, and arc basement may add further complexity to the elemental and iso...

The Columbia (Nuna) supercontinent existed from approximately 1.9 Ga to 1.3 Ga. Laurentia was part of Columbia, and the western edge of Laurentia (current coordinates) was likely proximal to a large landmass during parts of this interval. Here, we present detrital zircon ages of a Paleoproterozoic sedimentary succession in northern Yukon, Canada, t...

Accretionary orogens such as the NW Cordillera are often long lived and represent a collage of terranes amalgamated through multiple phases of deformation. In order to understand the early development of these orogens, key crustal components present during these early stages must be identified and studied in detail to unravel present day structural...

Understanding of the formation of accretionary orogens requires investigations of the timing, kinematics and mechanisms of terrane accretion. In the NW Cordillera, the Slide Mountain oceanic terrane (SMT) formed between Phanerozoic island arcs and the North American continent (NAC) during Devonian-Permian times and subsequently recorded multiple de...

The Mount Hickman ultramafi c complex (Triassic) is a composite Alaskan-type ultramafic pluton in Stikine terrane, northwestern British Columbia. Cumulate rocks in the complex are mainly olivine ±magnetite clinopyroxenite, but include subordinate serpentinized dunite, wehrlite, and gabbro. Magnetite is a volumetrically significant primary phase, es...

The abundance of trace elements in native gold is a useful tool for fingerprinting and provenance studies, as well as gaining insights into the physical and chemical conditions of gold mineralization. In-situ analytical techniques, using either electron probe microanalysis or laser ablation-inductively coupled plasma-mass spectrometry, are preferre...

The uraniferous, Proterozoic Otish Basin of the southeastern Superior Province hosts shallow-dipping sills and northeast to northwest-trending dykes of the Otish Gabbro suite and the north-trending Matoush dyke. Otish Gabbro sills comprise two distinct geochemical groups that reflect different degrees of crystal accumulation in a common olivine-tho...

Primitive picritic (MgO ≥12 wt.%) magmas are rare in arc settings, and limited to several spatially and temporally restricted occurrences in the Solomon Islands, Vanuatu, Lesser Antilles, Japan, and the Aleutian Islands. Explosive picritic volcanism is even more unusual, and has been identified only in non-arc settings including at Etna Volcano (re...

Development of northern Stikinia was characterized by late Triassic to Jurassic magmatism and porphyry mineralization including episodic magmatic flare-ups and radical changes in the nature of magmatism. These were likely triggered by catastrophic events in the lower crust, mantle, and subducting slab. Ultramafic (MgO =21-33 wt. %) tuff breccia, la...

Primitive lavas, mantle xenoliths, and melting experiments indicate that the bulk of the Earth's mantle has a limited range of Mg-numbers, centered at ~0.90. The relatively low FeO content of the Earth's mantle (~8 wt. %) contrasts with the relatively high inferred FeO contents of the Martian mantle and of the basaltic meteorites derived from the a...

Significant volumes of mantle-derived magma, evidenced by extensive mafic dyke swarms and thick gabbroic sills, intruded the Superior Craton during the Paleoproterozoic (ca. 1880-2500 Ma). The Otish Gabbro, Biscotasing, and Payne River suites and the coeval mafic volcanics in the Labrador Trough were emplaced along the southern and eastern present-...

The Otish Basin of central Québec hosts over thirty uranium prospects, including the Camie River prospect that is located near the unconformable contact between the graphite-bearing, metamorphic basement of Archean age and the overlying basinal sedimentary rocks of the Otish Supergroup. The maximum age of the basin, constrained by the age of the un...

Mafic to ultramafic intrusions of the Qullinaaraaluk suite (Q-suite) were emplaced into the Ungava craton of the Northeastern Superior Province during an episode of intense igneous activity and crustal reworking from c. 2.74 to 2.70 Ga. Orthopyroxene-rich Q-suite intrusions from the Hudson Bay Terrane and southwestern Riviere ArnaudTerrane, and ort...

The high iron content (FeOTOT >14 wt. %) of the global suite of Neoarchean ferropicritic lavas and plutonic rocks cannot be produced by the melting of the “pyrolitic” (Mg # =0.88-0.92) peridotite that is thought to make up the bulk of the Earth’s mantle. Although most would agree that the Mg #’s of their mantle sources are low (<0.85), possibly app...

The Superior Province of North America experienced multiple episodes of mafic magmatism during the Paleoproterozoic, each providing information on the temporal and spatial variations in the composition of the mantle underlying the Earth’s largest craton. Gabbroic dykes and sills of the Otish suite were emplaced into the conglomerate and sandstone-d...

The iron content (FeOTOT > 14 wt. %) of ferropicritic magmas is too high to reflect melting of “pyrolitic” (Mg/(Mg+Fe) = 0.88-0.92) sources that are believed to make up the majority of the Earth’s mantle. Although the composition and mineralogy of ferropicrite sources are poorly constrained, it is widely accepted that their Mg/(Mg+Fe) ratios are lo...

The intracratonic Paleoproterozoic Otish Basin of the southeastern Superior Province hosts several uranium deposits, including Camie River and Matoush (586,000 t at 0.95 % U3O8). The uranium mineralization is complex but some deposits (eg. Matoush) are spatially related to mafic dykes and sills, leading to the suggestion that the intrusion of the O...

The plutonic Qullinaaraaluk suite (Q-suite) of northern Ungava comprises small, cumulate ultramafic to mafic cumulate bodies that are scattered across the width of the Ungava Craton. The ca. 2.72 Ga emplacement ages, and the ubiquitous and wide spread occurrence of the Q-suite plutons, suggest that Neoarchean crustal reworking of the Ungava craton...

Zoned ultramafic/mafic plutonic rocks emplaced at mid-crustal depths occur scattered across the disparate terranes of the Ungava craton of the Archean Superior Province. These Qullinaaraaluk (Q-suite) intrusions are coeval with the ca. 2.74-2.72 Ga pyroxene-bearing granitoids and high-K granitoids that dominate the Ungava craton [1], and their wide...

Terra Nova, 23, 307–313, 2011 New U-Pb zircon dates from gneissic xenoliths in an Early Cambrian lamprophyre point to late Mesoproterozoic metamorphism and magmatism in the crust beneath northern Yukon. The data indicate a previously unrecognized thermal event in Yukon and extend the recognition of widely spaced 1.3–1.0 Ga igneous, metamorphic and...

The Neo-Archean was an important era of continental crust formation and a time of wide-spread mafic magmatism related to global-scale mantle melting. The Neo-Archean Ungava craton of northern Quebec is dominated by relatively-potassic ca. 2.74-2.72 Ga granitoids emplaced into an older, regionally-extensive ≥2.8 Ga crust. A large number of small (<1...

Thick, deformed and weakly metamorphosed successions of sedimentary rocks deposited during several extensional, basin-forming events between ca. 1.64 Ga and ca. 540 Ma, record Proterozoic tectonism and hydrothermal activity in east-central Yukon. A SHRIMP study of small (20-80 m), complexly zoned zircon grains from 5 xenoliths in an Early Cambrian...

The Early Cambrian Quartet Mountain lamprophyres are volatile-rich ultramafic alkaline dykes that cross-cut the Wernecke and Mackenzie mountains supergroups in the Wernecke Mountains of northern Yukon. Their emplacement may have been triggered by Early Paleozoic extension of the Cordilleran miogeocline. Numerous small-volume alkalic igneous rocks t...