Geological setting, U–Pb geochronology, and radiogenic isotopic characteristics of the Permo-Triassic Kutcho Assemblage, north-central British Columbia

1997 ◽  
Vol 34 (10) ◽  
pp. 1310-1324 ◽  
Author(s):  
Fiona C. Childe ◽  
John F.H. Thompson
Keyword(s):  
Hanging Wall ◽  
Volcanic Rocks ◽  
Isotopic Signature ◽  
Massive Sulphide ◽  
Pyroclastic Flows ◽  
Sulphide Mineralization ◽  
Isotopic Signatures ◽  
Arc Magmas ◽  
Volcanogenic Massive Sulphide ◽  
Mass Flows

The Kutcho Assemblage is a latest Permian to Early Triassic volcano-sedimentary sequence within the fault-bounded King Salmon Allochthon. Volcanic and volcaniclastic rocks consist of massive to pillowed flows and tuffs of basaltic to basaltic andesitic composition, as well as flows, mass flows, and pyroclastic flows of rhyodacitic to rhyolitic composition. The volcanic sequence is intruded by gabbro, diorite, trondhjemite, and quartz–plagioclase porphyry. Volcanic and intrusive rocks have tholeiitic magmatic affinities, with die exception of the gabbro sills and dykes, which are chemically similar to alkaline arc magmas. Cu–Zn volcanogenic massive sulphide mineralization at die Kutcho Creek deposit is hosted by rhyolite mass flows near me top of the Kutcho Assemblage. Rhyolite mass flows from the hanging wall and footwall to mineralization have U–Pb ages of 242 ± 1 and [Formula: see text], respectively, whereas a quartz–plagioclase porphyritic intrusion to the south of the mineralization has a U–Pb age of 244 ± 6 Ma. The dates determined in this study constrain a previously unknown age for massive sulphide mineralization in the Canadian Cordillera. Furthermore, the age of the Kutcho Assemblage and the primitive Pb isotopic signature of its contained syngenetic mineralization (207Pb/206Pb = 0.83988–0.84112 and 208Pb/206Pb = 2.0517–2.0556) are inconsistent with formation as part of the adjacent Stikine or Quesnel terranes. Primitive Nd isotopic signatures (εNd(initial) = +7.5 to +9.1) and trace and rare earth element chemistry indicate that volcanic rocks of the Kutcho Assemblage, related intrusions, and volcanogenic massive sulphide mineralization formed in an intraoceanic island arc environment, probably directly on oceanic crustal basement. Gabbro sills and dykes, which are interpreted to be slightly younger than volcanic rocks of the Kutcho Assemblage, appear to have formed in response to a change in the tectonic regime, perhaps as a result of a collisional event.

Petrogenesis of the 1.9 Ga mafic hanging wall sequence to the Flin Flon, Callinan, and Triple 7 massive sulphide deposits, Flin Flon, Manitoba, CanadaThis is a companion paper to DeWolfe, Y.M., Gibson, H.L., Lafrance , B., and Bailes, A.H. 2009. Volcanic reconstruction of Paleoproterozoic arc volcanoes: the Hidden and Louis formations, Flin Flon, Manitoba, Canada. Canadian Journal of Earth Sciences, 46: this issue.

2009 ◽  
Vol 46 (7) ◽  
pp. 509-527 ◽  
Author(s):  
Y. M. DeWolfe ◽  
H. L. Gibson ◽  
S. J. Piercey
Keyword(s):  
Oceanic Crust ◽  
Basaltic Andesite ◽  
Hanging Wall ◽  
Volcanic Rocks ◽  
Companion Paper ◽  
Massive Sulphide ◽  
Massive Sulphide Deposits ◽  
Volcanogenic Massive Sulphide ◽  
Flin Flon ◽  
Sulphide Deposits

A detailed study of the geochemical and isotopic characteristics of the volcanic rocks of the Hidden and Louis formations, which make up the hanging wall to the volcanogenic massive sulphide deposits at Flin Flon, Manitoba, was carried out on a stratigraphically controlled set of samples. The stratigraphy consists of the lowermost, dominantly basaltic, Hidden formation, and the overlying, dominantly basaltic, Louis formation. Of importance petrogenetically, is the 1920 unit a basaltic andesite with Nb/Thmn = 0.54–0.62, εNd(1.9Ga) = +3.6–+5.9, εHf(1.9Ga) = +8.5–+9.6, and 204Pb/206Pb = 23.9. The basaltic flows that dominate the Hidden formation have Nb/Thmn = 0.16–0.29, εNd(1.9Ga) = +1.7–+4.4, εHf(1.9Ga) = +7.0–+11.8 and 204Pb/206Pb = 16.9–18.6). The Carlisle Lake basaltic–andesite (top of Hidden formation) is characterized by Nb/Thmn = 0.16–0.14, and 204Pb/206Pb = 21.4. The rhyodacitic Tower member (bottom of Louis formation) has Nb/Thmn = 0.23, εNd1.9Ga = +4.6, εHf1.9Ga = +9.3, and 204Pb/206Pb = 22.2. The basaltic flows that dominate the Louis formation have Nb/Thmn = 0.18–0.25, εNd(1.9Ga) = +3.6–+4.2, εHf(1.9Ga) = +8.4–+11.3 and 204Pb/206Pb = 17.9. The Hidden and Louis formations show dominantly transitional arc tholeiite signatures, with the 1920 unit having arc tholeiite characteristics. It is interpreted to have formed through extensive fractional crystallization of differentiated magmas at shallow levels in oceanic crust. Given the geological, geochemical, and isotopic characteristics of the Hidden and Louis formations, they are interpreted to represent subducted slab metasomatism with minor contamination from subducted sediments.

Mineralogy, textural characteristics and mineral chemistry of remobilised sulphides and sulphosalts in the Rävliden Norra VMS deposit, Skellefte district, northern Sweden

2020 ◽  
Author(s):  
Jonathan Rincon ◽  
Simon Johansson ◽  
Nils Jansson ◽  
Helen Thomas ◽  
Majka Christiane Kaiser ◽  
...  
Keyword(s):  
Boundary Migration ◽  
Hanging Wall ◽  
Volcanic Rocks ◽  
Mineral Chemistry ◽  
Massive Sulphide ◽  
Ductile Deformation ◽  
Sulphide Mineralization ◽  
Micro Scale ◽  
Metasedimentary Rocks ◽  
Skellefte District

<p>Remobilisation of sulphides in metamorphosed volcanic-hosted massive sulphide deposits has been investigated in many VMS districts with regards to scale, mineral assemblages, texture and relative competence of minerals under certain p-t conditions (Gilligan & Marshall, 1987; Marshall & Gilligan, 1987). Examples of syn-tectonic remobilisation can be found at the Rävliden Norra (RVN) volcanic-hosted massive sulphide in the Skellefte district. At Rävliden, polymetallic sulphide mineralization occurs at the transition from meta-volcanic rocks of the Skellefte group rocks to the overlying Vargfors group, comprising volcaniclastic metasedimentary rocks and graphitic shales. This contribution details features of mesoscale (0.1-50 cm) remobilisation of sulphides, such as sulphide-rich veins, tension gashes, ball-ore, massive sulphides with cataclastic texture, and micro-scale features such as infilling of pressure shadows, displaying evidences of brittle and ductile deformation. Sulphide-rich veins containing sphalerite, galena, and a relative high content of Ag-sulphosalts (e.g. freibergite, pyrargyrite, pyrostilpnite) are hosted in the hanging wall (HW) of the RVN mineralization. Brittle deformation is shown in accessory quartz and calcite as bulging recrystallization, grain boundary migration and deformation lamellae or twinning. Ductile expressions include ball-ore (i.e. “durchbewegung”) textures, typically made up of two components, one composed of clasts of graphite shale or tremolite-, actinolite-, talc-altered meta-volcanic rocks and the other comprising a matrix of massive sulphide mineralization. In the massive sulphide matrix of sphalerite, chalcopyrite or pyrrhotite, micro-scale tension gashes and/or pressure shadows occur around clasts infilled by pyrrhotite, chalcopyrite, galena, freibergite, boulangerite, or gudmundite. A similar mineralogy is observed in ore lenses in the ore zone, comprising sphalerite, galena and Ag-Sb-As sulphosalts, hosted structurally above chalcopyrite + pyrrhotite stringer zones in the footwall (FW). Sulphosalts and galena present a high silver content relative to other VMS deposits in the district. This is evidenced by SEM and EMPA analysis in both HW and FW ore lenses. Argentopyrite, sternbergite and stephanite are also locally present in the HW as minor silver species hosted in veins. Inclusions of freibergite in galena contain Ag with average values of 18.4 wt. % in the HW (n=5), 18 wt. % in the massive sphalerite and ball-ore (n= 15), and 20.2 wt. % in the chalcopyrite + pyrrhotite stringer zone (n= 5). Similarly, Pb is 0.2 wt. %, 0.3 wt. %, and 0.4 wt. %, respectively. For sphalerite, Fe is on average 8.0 wt. % (n=3), 7.4 wt. % (n = 11), and 8.3 wt. % (n=3), respectively. Our preliminary results suggest that mineralization in the HW is remobilized from the main ore and textural relationships support a hypothesis that remobilisation involved a relative silver-enrichment in paragenetically later assemblages. At least two stages of deformation in the deposit can be recognized. In the first stage, sphalerite- and chalcopyrite-rich mineralization was deformed along with tremolite and talc to form a S1 foliation. The second stage involved folding of S1, and remobilisation of galena, chalcopyrite and Ag-Sb-As sulphosalts as veins or breccia infill in the HW or filling tension gaps or ball-ore, in the FW. These are often parallel to S2 crenulation or axial planes.</p>

Volcanic reconstruction of Paleoproterozoic arc volcanoes: the Hidden and Louis formations, Flin Flon, Manitoba, CanadaThis is a companion paper to DeWolfe, Y.M., Gibson, H.L., and Piercey, S.J. 2009. Petrogenesis of the 1.9 Ga mafic hanging wall sequence to the Flin Flon, Callinan, and Triple 7 massive sulphide deposits, Flin Flon, Manitoba, Canada. Canadian Journal of Earth Sciences, 46: this issue.

2009 ◽  
Vol 46 (7) ◽  
pp. 481-508 ◽  
Author(s):  
Y. M. DeWolfe ◽  
H. L. Gibson ◽  
B. Lafrance ◽  
A. H. Bailes
Keyword(s):  
Hanging Wall ◽  
Massive Sulphide ◽  
Gradual Change ◽  
Shield Volcano ◽  
Ore Formation ◽  
Massive Sulphide Deposits ◽  
Volcanogenic Massive Sulphide ◽  
Volcaniclastic Rocks ◽  
Flin Flon ◽  
Sulphide Deposits

The hanging wall to the Flin Flon, Callinan, and Triple 7 volcanogenic massive sulphide deposits of the Flin Flon district is composed of the Hidden and Louis formations. The contact between these formations is marked by mafic tuff that represents a hiatus in effusive volcanism. The formations form a composite volcanic edifice that was erupted and grew within a large, volcanic–tectonic subsidence structure (hosting the deposits) that developed within a rifted-arc environment. The formations are evidence of resurgent effusive volcanism and subsidence following a hiatus in volcanism marked by ore formation since they consist of dominantly basaltic flows, sills, and volcaniclastic rocks with subordinate basaltic andesite and rhyodacitic flows and volcaniclastic rocks. The Hidden formation is interpreted to represent a small shield volcano and the Louis formation a separate shield volcano that developed on its flank. Both the Hidden and Louis volcanic edifices were constructed by continuous, low-volume eruptions of pillow lava. A gradual change from a dominantly extensional environment during the formation of the footwall Flin Flon formation to a progressively more dominant convergent environment during the emplacement of the hanging wall suggests that the Hidden and Louis formations are unlikely to host significant volcanogenic massive sulphide-type mineralization. However, synvolcanic structures in the formations define structural corridors that project downwards into the footwall where they encompass massive sulphide mineralization, indicating their control on ore formation, longevity,and reactivation as magma and fluid pathways during the growth of the Hidden and Louis volcanoes.

scholarly journals The Moroccan Massive Sulphide Deposits: Evidence for a Polyphase Mineralization

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 156 ◽  
Author(s):  
Abderrahim Essaifi ◽  
Kathryn Goodenough ◽  
Fernando Tornos ◽  
Abdelhak Outigua ◽  
Abdelmalek Ouadjou ◽  
...  
Keyword(s):  
Lead Isotopes ◽  
Shear Zones ◽  
Structural Features ◽  
Isotopic Signature ◽  
Ore Deposits ◽  
Massive Sulphide ◽  
Isotopic Signatures ◽  
Crustal Block ◽  
Massive Sulphide Deposits ◽  
Sulphide Deposits

This work provides an overview of the geological, geochemical, and metallogenic data available up to date on the Moroccan massive sulphide deposits, including some new results, and then discusses the evidences for the epigenetic and syngenetic hypotheses. All of the ore deposits are located within a crustal block located at the intersection between two major shear zones and are characterized by a sustained and long-lived magmatic activity. The ore deposits are located within second-order shear zones, which played an important role in controlling the geometry of the mineralization. The mineralization lacks the unequivocal textural and structural features that are indicative of a sedimentary or diagenetic origin, and a syntectonic to late-tectonic pyrite-rich assemblage is superimposed on an earlier, pretectonic to syntectonic pyrrhotite-rich mineralization. Each deposit has a distinctive pyrrhotite sulfur isotopic signature, while the sulfur isotopic signature of pyrite is similar in all deposits. Lead isotopes suggest a shift from a magmatic source during the pyrrhotite-rich mineralization to a source that is inherited from the host shales during the pyrite-rich mineralization. The O/H isotopic signatures record a predominance of fluids of metamorphic derivation. These results are consistent with a model in which an earlier pyrrhotite-rich mineralization, which formed during transtension, was deformed and then remobilized to pyrite-rich mineralization during transpression.

Physical volcanology of the footwall rocks near the Mattabi massive sulphide deposit, Sturgeon Lake, Ontario

1988 ◽  
Vol 25 (2) ◽  
pp. 280-291 ◽  
Author(s):  
D. A. Groves ◽  
R. L. Morton ◽  
J. M. Franklin
Keyword(s):  
Repetitive Sequences ◽  
Volcanic Rocks ◽  
Massive Sulphide ◽  
Lava Flows ◽  
Pyroclastic Flows ◽  
Lake Area ◽  
Massive Sulphide Deposit ◽  
Sulphide Deposit ◽  
Water Influx ◽  
Felsic Lava

Subaerial and shallow subaqueous mafic hyalotuffs, lava flows, and flow breccias, felsic lava flows, and pyroclastic flows and falls form a 2 km thick succession beneath the Mattabi massive sulphide deposit. The lowermost 800 m of section comprises massive to amygdaloidal mafic flows and flow breccias interlayered with repetitive sequences of thinly bedded felsic tuff: pillow lavas and hyaloclastites are absent. Amygdaloidal felsic lavas overlie the mafic flows and are locally capped by coarse explosion breccia. This breccia is believed to represent the start of mafic hydrovolcanism, which produced ash falls, surges, and flows. These pyroclastic deposits formed thin- to thick-bedded hyalotuffs that contain highly vesicular and quenched juvenile and accessory lithic fragments. Periods of water influx probably led to the construction of a tuff cone, which represents a submergent hydrovolcanic cycle.In the Mattabi area, pyroclastic flow deposits form the immediate mine footwall strata and include (i) massive basal beds and overlying bedded ash tuffs and (ii) massive pumiceous units. These deposits overlie and, to the west in the Darkwater Lake area, are intercalated with the mafic hyalotuff sequence. The morphology of the footwall volcanic rocks indicates that the Mattabi and the F-zone massive sulphide deposits formed in a shallow subaqueous environment.

Mineralogy and genesis of calc-silicates associated with Archean volcanogenic massive sulphide deposits at the Manitouwadge mining camp, Ontario

1992 ◽  
Vol 29 (7) ◽  
pp. 1375-1388 ◽  
Author(s):  
Yuanming Pan ◽  
Michael E. Fleet
Keyword(s):  
Regional Metamorphism ◽  
Spatial Association ◽  
Volcanic Rocks ◽  
Granulite Facies ◽  
Massive Sulphide ◽  
Sea Floor ◽  
Massive Sulphide Deposits ◽  
Volcanogenic Massive Sulphide ◽  
Reducing Environment ◽  
Sulphide Deposits

Skarn-like calc-silicate rocks are reported in spatial association with the Archean Cu–Zn–Ag massive sulphide deposits at the Manitouwadge mining camp, Ontario. Calc-silicates in the footwall of the Willroy mine occur as matrix to breccia fragments of garnetiferous quartzo-feldspathic gneiss and as lenses within garnetiferous quartzo-feldspathic gneiss and are composed of clinopyroxene, garnet, calcic amphiboles, wollastonite, plagioclase, K-feldspar, epidote, quartz, calcite, magnetite, and minor sulphides. Calc-silicates within the main orebody of the Geco mine are characterized by clinopyroxene, calcic amphiboles (Cl–K-rich hastingsitic and ferro-edenitic hornblende, ferro-edenite (up to 4.7 wt.% Cl); and ferroactinolite (6.7 wt.% MnO)), garnet, epidote (including an epidote rich in rare-earth elements and Cl), calcite, quartz, and abundant sulphides. Calc-silicates within the basal 4/2 Copper Zone of the Geco mine contain garnet, gahnite, sphalerite, ferroactinolite (8.5 wt.% MnO), epidote, quartz, biotite, plagioclase, chlorite, muscovite, K-feldspar, and pyrosmalite (with Mn/(Mn + Fe) ratio ranging from 0.21 to 0.61, and up to 3.9 wt.% Cl). The calc-silicates probably represent metasomatic remobilization of dispersed Ca (and Cl) from sea-floor hydrothermal alteration of mafic to intermediate volcanic rocks and are only indirectly related to the hypothesized syngenetic ore-forming processes for the associated base metal sulphide deposits. The calc-silicates formed initially at about 600 °C and 3–5 kbar (1 kbar = 100 MPa) in a mildly reducing environment (from 1 log unit above to 1 log unit below the fayalite–magnetite–quartz buffer) during the upper-amphibolite- to granulite-facies regional metamorphism and were altered subsequently at lower temperatures (<500 °C).

Geology, geochronology, and fluid inclusion studies of the Xiaorequanzi volcanogenic massive sulphide Cu–Zn deposit in the East Tianshan Terrane, China

2020 ◽  
Vol 57 (12) ◽  
pp. 1392-1410 ◽  
Author(s):  
Xi-Heng He ◽  
Xiao-Hua Deng ◽  
Leon Bagas ◽  
Jing Zhang ◽  
Chao Li ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Fluid Inclusions ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Massive Sulphide ◽  
Calc Alkaline ◽  
The North ◽  
Volcanogenic Massive Sulphide ◽  
Secondary Fluid ◽  
East Tianshan

The Xiaorequanzi Cu–Zn deposit is in the westernmost part of East Tianshan Terrane in northwestern China. The deposit is unique in the region being a volcanogenic massive sulphide (VMS) deposit located near a zone (or belt) containing giant late Paleozoic porphyry Cu deposits. Aiming to better understand the genesis of the mineral deposits in the terrane and their tectonic setting, we report our findings of detailed studies on fluid inclusion microthermometry, Re–Os dating of chalcopyrite from the massive ore, and U–Pb dating of zircons from the host volcanic rocks. There are two sulphide stages with early pyrite succeeded by chalcopyrite–sphalerite, which are hydrothermally overprinted and supergene enriched. The hydrothermal overprinting is characterised by quartz–sulphide veins crossed by carbonate-rich quartz veins. Quartz from the chalcopyrite–sphalerite stage is characterised by primary fluid inclusions containing H2O–NaCl(–CO2) and homogenise at 228–392 °C with a salinity of 2.2–13.3 wt.% NaCl equiv. Secondary fluid inclusions related to the hydrothermal overprinting homogenise at 170–205 °C with a salinity of 2.7–12.1 wt.% NaCl equiv. Fluid inclusions in the quartz–sulphide stage of the hydrothermal overprinting contain H2O–NaCl with homogenisation temperatures of 164–281 °C and salinities in ranging from 2.9 to 12.4 wt.% NaCl equiv. Fluid inclusion in the quartz–calcite stage contain H2O–NaCl with homogenisation temperatures of 122–204 °C with salinities of 1.4–12.4 wt.% NaCl equiv. These characteristics are like those of the secondary fluid inclusions in the VMS mineralisation. Combining these findings with H–O isotopic data from previous studies, we propose that the primary mineralising fluid is magmatic in origin. Tuff hosting the mineralisation yields a SHRIMP U–Pb zircon age of 352 ± 5 Ma, which is interpreted as the age of the tuff, and a porphyritic felsite dyke intruding the tuff yields a SHRIMP U–Pb zircon date of 345 ± 6 Ma, interpreted as the emplacement age of the dyke. Chalcopyrite from the main orebody at Xiaorequanzi yields a Re–Os isochron age of 336 ± 13 Ma with an initial 187Os/188Os ratio of 0.25 ± 0.55 (MSWD = 12). Given that the VMS deposit is a syngenetic deposit, we regard the upper ca. 349 Ma limit of the Re–Os date as the approximate age of the chalcopyrite. The three dates are the same within error, and the upper limit of the Re–Os date of ca. 349 is taken as the age of the volcanic, dyke, and mineralisation. The volcanic rocks around the Xiaorequanzi deposit have been previously classified as calc–alkaline to high-K calc–alkaline enriched in large-ion lithophile elements and depleted in high-field-strength elements, which are characteristics indicative of a forearc setting. It is suggested that VMS mineralisation formed in a forearc setting related to the north-directed subduction of the Palaeo-Kangguer or North Tianshan oceanic plates.

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