The Sudbury Igneous Complex: A Differentiated Impact Melt Sheet

Therriault, A. M.; Fowler, Anthony D.; Grieve, R. A. F.

doi:10.2113/gsecongeo.97.7.1521

Cited by 127 publications

(86 citation statements)

References 60 publications

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“…Chemical zoning has also been recognized for other Offset Dikes and attributed to (1) flow differentiation (Grant and Bite 1984;Prevec et al 2000), (2) multiple injection of melt either during the differentiation of the Main Mass of the SIC and Sublayer (Grant and Bite 1984;Ostermann et al 1995) or (4) late magmatic (deuteric) alteration (Grant and Bite 1984;Deutsch 1994;Corfu and Lightfoot 1996;Therriault et al 2002). In order to assess these mechanisms, we discuss individual processes of differentiation for the Worthington Dike.…”

Section: Mechanisms Of Dike Differentiationmentioning

confidence: 94%

“…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%

“…In contrast to short-term ("catastrophic") modes of dike formation, it has been suggested that emplacement of quartzdioritic melts on time scales on the order of tens to hundreds of thousands of years resulted from crater floor fracturing driven by isostatic readjustment of the crust (Wichmann and Schultz 1993), post-impact cooling and contraction of host target rocks below the Main Mass of the SIC (Riller 2005) and tectonism following crater formation (Therriault et al 2002). These modes of dike formation most likely involved laminar melt flow, during incremental opening of fractures in the crater floor.…”

Section: Introductionmentioning

confidence: 99%

“…Existing rival interpretations are for example: (1) the Offset Dikes represent a melt that was geochemically equivalent to the Main Mass of the SIC before it differentiated (Lightfoot et al 1997b;Lightfoot and Farrow 2002;Tuchscherer and Spray 2002). (2) The dike melts derived from intermediate stages of fractional crystallization (± contamination) of the Main Mass of the SIC (Wood and Spray 1998;Prevec et al 2000;Therriault et al 2002), or (3) radial dikes including the Sublayer sensu stricto (Fig. 1b) are closely related to an endogenic intrusion that is younger than the granophyre Eckstrand 1993, 1994) and possibly younger than the norite (Dressler et al 1996).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Mechanisms Of Dike Differentiationmentioning

confidence: 94%

Section: Emplacement Of the Worthington Dikementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…Similarly, rigid and rapidly quenched tagamite melts seem to be present at Popigai before the emplacement of suevites (Whitehead et al 2002). Even the impact melt at Sudbury (e.g., Therriault et al 2002) must have had a sufficiently rigid quench zone at the top to mechanically support the deposition and weight of the overlying Onaping formation. These examples show that massive impact melts may quench rather solid melt sheet margins while suevitic ejecta are still being produced and emplaced.…”

Section: Implications For Transport Deposition and Modificationmentioning

confidence: 99%

Impact lithologies and their emplacement in the Chicxulub impact crater: Initial results from the Chicxulub Scientific Drilling Project, Yaxcopoil, Mexico

Kring

Hörz

Zürcher

et al. 2004

Meteorit & Planetary Scien

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Abstract-The Chicxulub Scientific Drilling Project (CSDP), Mexico, produced a continuous core of material from depths of 404 to 1511 m in the Yaxcopoil-1 (Yax-1) borehole, revealing (top to bottom) Tertiary marine sediments, polymict breccias, an impact melt unit, and one or more blocks of Cretaceous target sediments that are crosscut with impact-generated dikes, in a region that lies between the peak ring and final crater rim. The impact melt and breccias in the Yax-1 borehole are 100 m thick, which is approximately 1/5 the thickness of breccias and melts exposed in the Yucatán-6 exploration hole, which is also thought to be located between the peak ring and final rim of the Chicxulub crater. The sequence and composition of impact melts and breccias are grossly similar to those in the Yucatán-6 hole. Compared to breccias in other impact craters, the Chicxulub breccias are incredibly rich in silicate melt fragments (up to 84% versus 30 to 50%, for example, in the Ries). The melt in the Yax-1 hole was produced largely from the silicate basement lithologies that lie beneath a 3 km-thick carbonate platform in the target area. Small amounts of immiscible molten carbonate were ejected with the silicate melt, and clastic carbonate often forms the matrix of the polymict breccias.The melt unit appears to have been deposited while molten but brecciated after solidification. The melt fragments in the polymict breccias appear to have solidified in flight, before deposition, and fractured during transport and deposition.

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Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

Huang

Strati

Mantovani

et al. 2014

Geochem. Geophys. Geosyst.

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The SNO1 detector that is currently under construction in Ontario, Canada, will be a new kilotonscale liquid scintillation detector with the capability of recording geoneutrino events that can be used to constrain the strength of the Earth's radiogenic power, and in turn, to test compositional models of the bulk silicate Earth (BSE). We constructed a detailed 3-D model of the regional crust centered at SNO1 from compiled geological, geophysical, and geochemical information. Crustal cross sections obtained from refraction and reflection seismic surveys were used to characterize the crust and assign uncertainties to its structure. The average Moho depth in the study area is 42.3 6 2.6 km. The upper crust was divided into seven dominant lithologic units on the basis of regional geology. The abundances of U and Th and their uncertainties in each upper crustal lithologic unit were determined from analyses of representative outcrop samples. The average chemical compositions of the middle and lower crust beneath the SNO1 region were determined by coupling local seismic velocity profiles with a global compilation of the chemical compositions of amphibolite and granulite facies rocks. Monte Carlo simulations were used to predict the geoneutrino signal originating from the regional crust at SNO1 and to track asymmetrical uncertainties of U and Th abundances. The total regional crust

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The Sudbury Igneous Complex: A Differentiated Impact Melt Sheet

Cited by 127 publications

References 60 publications

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

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

Impact lithologies and their emplacement in the Chicxulub impact crater: Initial results from the Chicxulub Scientific Drilling Project, Yaxcopoil, Mexico

Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

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