Vitric Compositions in the Onaping Formation and Their Relationship to the Sudbury Igneous Complex, Sudbury Structure

Ames, D E; Golightly, J. P.; Lightfoot, Peter C.; Gibson, H. L.

doi:10.2113/gsecongeo.97.7.1541

Cited by 61 publications

(89 citation statements)

References 47 publications

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“…High temperature reaction zones generally contain the assemblage actinolite-hornblendeclinopyroxene and epidote. In the large Sudbury impact crater, regional, vertically stacked alteration zones occur with increasing depth and paleo-temperatures (up to 250-300 °C) in the impact crater fill sequence (Ames et al 1998(Ames et al , 2002b. Alteration of the Yax-1 core characterized by Mgsaponite, K-montmorillonite, celadonite, Fe-oxides, and Kfeldspar is typical of low-temperature (0-150 °C) seawater recharge zones.…”

Section: Discussionmentioning

confidence: 99%

“…The massive sulfide deposits indicate focused hydrothermal venting at 200-250 °C, while the exhalites that are in part carbonate-facies iron formation indicate lower temperature but extensive, diffuse low temperature venting over large areas (Ames et al 1998(Ames et al , 2000(Ames et al , 2002a. The sulfide deposits of the Sudbury crater floor vent systems are a modest economic resource at 6.4 Mt (Ames et al 2002b), however the magmatic Ni-Cu and magmatic-hydrothermal Cu-PGE deposits that developed at the base of the Sudbury melt sheet comprise the largest mineral deposits in the world (e.g., Naldrett 2003).…”

Section: Crater Floor Hydrothermal Vents and Massive Sulfide Deposits?mentioning

confidence: 99%

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Secondary alteration of the impactite and mineralization in the basal Tertiary sequence, Yaxcopoil‐1, Chicxulub impact crater, Mexico

Ames

Kjarsgaard

Pope³

et al. 2004

Meteorit & Planetary Scien

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Abstract-The 65 Ma Chicxulub impact crater formed in the shallow coastal marine shelf of the Yucatán Platform in Mexico. Impacts into water-rich environments provide heat and geological structures that generate and focus sub-seafloor convective hydrothermal systems. Core from the Yaxcopoil-1 (Yax-1) hole, drilled by the Chicxulub Scientific Drilling Project (CSDP), allowed testing for the presence of an impact-induced hydrothermal system by: a) characterizing the secondary alteration of the 100 m-thick impactite sequence; and b) testing for a chemical input into the lower Tertiary sediments that would reflect aquagene hydrothermal plume deposition. Interaction of the Yax-1 impactites with seawater is evident through redeposition of the suevites (unit 1), secondary alteration mineral assemblages, and the subaqueous depositional environment for the lower Tertiary carbonates immediately overlying the impactites. The least-altered silicate melt composition intersected in Yax-1 is that of a calc-alkaline basaltic andesite with 53.4-56 wt% SiO 2 (volatile-free) . The primary mineralogy consists of fine microlites of diopside, plagioclase (mainly Ab 47), ternary feldspar (Ab 37 to 77), and trace apatite, titanite, and zircon. The overprinting alteration mineral assemblage is characterized by Mg-saponite, Kmontmorillonite, celadonite, K-feldspar, albite, Fe-oxides, and late Ca and Mg carbonates. Mg and K metasomatism resulted from seawater interaction with the suevitic rocks producing smectite-Kfeldspar assemblages in the absence of any mixed layer clay minerals, illite, or chlorite. Rare pyrite, sphalerite, galena, and chalcopyrite occur near the base of the impactites. These secondary alteration minerals formed by low temperature (0-150 °C) oxidation and fixation of alkalis due to the interaction of glass-rich suevite with down-welling seawater in the outer annular trough intersected at Yax-1. The alteration represents a cold, Mg-K-rich seawater recharge zone, possibly recharging higher temperature hydrothermal activity proposed in the central impact basin. Hydrothermal metal input into the Tertiary ocean is shown by elevated Ni, Ag, Au, Bi, and Te concentrations in marcasite and Cd and Ga in sphalerite in the basal 25 m of the Tertiary carbonates in Yax-1. The lower Tertiary trace element signature reflects hydrothermal metal remobilization from a mafic source rock and is indicative of hydrothermal venting of evolved seawater into the Tertiary ocean from an impactgenerated hydrothermal convective system.

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Section: Discussionmentioning

confidence: 99%

Section: Crater Floor Hydrothermal Vents and Massive Sulfide Deposits?mentioning

confidence: 99%

Secondary alteration of the impactite and mineralization in the basal Tertiary sequence, Yaxcopoil‐1, Chicxulub impact crater, Mexico

Ames

Kjarsgaard

Pope³

et al. 2004

Meteorit & Planetary Scien

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“…The geology is described in detail in the volume edited by Pye et al (1984). The Sudbury Igneous Complex formed from a meteorite impact, which flash-melted the Archaen and Proterozoic crust resulting in its distinctive continental isotopic signature (Faggart et al, 1985) and andesitic bulk composition (Ames et al, 2002). The melt sheet differentiated to form norite in the Lower Unit, an oxide-rich quartz gabbro (<10% Fe-oxide and apatite) in the Middle Unit and granophyre of granitic composition in the Upper Unit (e.g., Gasparrini and Naldrett, 1972;Therriault et al, 2002).…”

Section: Geologic Settingmentioning

confidence: 99%

“…1). The (Pt + Pd)/IPGE Normalization to bulk continental crust, using values from Rudnick and Gao (2003), is appropriate for magnetite from Sudbury as the initial Sudbury melt was bulk continental crust in composition (Ames et al, 2002). Elements which are not significantly above detection limit are not plotted.…”

Section: Samplesmentioning

confidence: 99%

Variation in trace element content of magnetite crystallized from a fractionating sulfide liquid, Sudbury, Canada: Implications for provenance discrimination

Dare¹,

Barnes²,

Beaudoin³

2012

Geochimica et Cosmochimica Acta

278

154

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“…As mentioned previously, this would result in a melt replete with marginally corroded mafic xenoliths. Moreover, the decrease in temperature of the impact melt likely caused, at least locally, a relative increase in the volume of assimilated leucocratic rocks or felsic partial melts and Meldrum et al (1997), 1b: Ostermann (1996 and Prevec (1993), 2a: Cartier Granite after Meldrum et al (1997), 2b: Ramsey Algoman Complex after Prevec (1993), 3a: Lightfoot and Naldrett (1996), 3b: Ames et al (2002), 3c: this study (see Table 2), 3d: Mourre (2000), 4: Jolly et al (1992), 5a : Jolly et al (1992), 5b: Prevec (1993), 6a: Lightfoot and Naldrett (1996), 6b: Ostermann (1996), 6c: Prevec (1993, 6d: Sudbury Gabbro by Lightfoot and Farrow (2002), 6e: Sudbury Gabbro as amphibolite inclusion in Worthington Offset Dike Farrow 2002), 7: Ostermann (1996), 8a and 9a: McLennan (1985, 1995) and McLennan (2001), 8b and 9b: Rudnick andGao (2003), 10: Lightfoot et al (1997a), Wood and Spray (1998), Murphy and Spray (2002), Tuchscherer andSpray (2002), 11: Lightfoot et al (1997a), Lightfoot and Farrow (2002), Mourre (2000), 12a, 13a and 14a: Therriault et al (2002), 12b and 13b: Lightfoot et al (1997b), 14b: Felsic Norite by Lightfoot et al (1997b), 15a: Least altered vitric composition of Onaping Formation after Ames et al (2002), 15b: Ostermann (1996. thus, to a shift towards less mafic compositions of the basal melt layer.…”

Section: Emplacement Of the Worthington Dikementioning

confidence: 99%

Differentiation and emplacement of the Worthington Offset Dike of the Sudbury impact structure, Ontario

Hecht

Wittek

Riller

et al. 2008

Meteorit & Planetary Scien

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Abstract-The Offset Dikes of the 1.85 Ga Sudbury Igneous Complex (SIC) constitute a key topic in understanding the chemical evolution of the impact melt, its mineralization, and the interplay between melt migration and impact-induced deformation. The origin of the melt rocks in Offset Dikes as well as mode and timing of their emplacement are still a matter of debate. Like many other offset dikes, the Worthington is composed of an early emplaced texturally rather homogeneous quartz-diorite (QD) phase at the dike margin, and an inclusion-and sulfide-rich quartz-diorite (IQD) phase emplaced later and mostly in the centre of the dike. The chemical heterogeneity within and between QD and IQD is mainly attributed to variable assimilation of host rocks at the base of the SIC, prior to emplacement of the melt into the dike. Petrological data suggest that the parental magma of the Worthington Dike mainly developed during the pre-liquidus temperature interval of the thermal evolution of the impact melt sheet (>1200 °C). Based on thermal models of the cooling history of the SIC, the two-stage emplacement of the Worthington Dike occurred likely thousands to about ten thousand years after impact. Structural analysis indicates that an alignment of minerals and host rock fragments within the Worthington Dike was caused by ductile deformation under greenschist-facies metamorphic conditions rather than flow during melt emplacement. It is concluded that the Worthington Offset Dike resulted from crater floor fracturing, possibly driven by late-stage isostatic readjustment of crust underlying the impact structure.

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Vitric Compositions in the Onaping Formation and Their Relationship to the Sudbury Igneous Complex, Sudbury Structure

Cited by 61 publications

References 47 publications

Secondary alteration of the impactite and mineralization in the basal Tertiary sequence, Yaxcopoil‐1, Chicxulub impact crater, Mexico

Secondary alteration of the impactite and mineralization in the basal Tertiary sequence, Yaxcopoil‐1, Chicxulub impact crater, Mexico

Variation in trace element content of magnetite crystallized from a fractionating sulfide liquid, Sudbury, Canada: Implications for provenance discrimination

Differentiation and emplacement of the Worthington Offset Dike of the Sudbury impact structure, Ontario

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