Fracturing, thermal evolution and geophysical signature of the crater floor of a large impact structure: The case of the Sudbury Structure, Canada

Milkereit, B.; Artemieva, N.; Ugalde, Hernan

doi:10.1130/2010.2465(08)

Cited by 3 publications

(17 citation statements)

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“…More recent numerical modeling by Milkereit et al. () supports slow cooling of the melt sheet, with similar cooling rates as predicted for conductive cooling according to Ivanov and Deutsch (). The numerical modeling shows strong vertical temperature gradients throughout the cooling history of the SIC.…”

Section: Constraints On Thermal Evolution Of the Melt Sheetsupporting

confidence: 67%

“…Milkereit et al. () predicted higher temperatures in deeper footwall over long time periods (>1 Myr).…”

Section: Constraints On Thermal Evolution Of the Melt Sheetmentioning

confidence: 95%

“… Modeling by Milkereit et al. () only considered the cooling process beginning from melt liquidus temperatures, so does not consider effects of supraliquidus heat in their modeling. …”

Section: Constraints On Thermal Evolution Of the Melt Sheetmentioning

confidence: 99%

“…; Milkereit et al. ), but in particular the reasons and mechanical aspects for the renewed magmatic injections that formed the younger and mineralized MIQD dykes are still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Multiphase emplacement of impact melt sheet into the footwall: Offset dykes of the Sudbury Igneous Complex, Canada

Prevec

Büttner

2018

Meteorit & Planetary Scien

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The offset dykes of the Sudbury Igneous Complex comprise two distinct main magmatic facies, a high‐temperature inclusion‐free quartz diorite (QD), and a subsequently intruded lower temperature, mineralized, and inclusion‐rich quartz diorite (MIQD). The MIQD facies was emplaced after QD dykes had solidified. Key controlling factors of the two injection phases were (1) the development of a coherent roof, which confined the melt sheet; and (2) the periodic increase of melt and fluid pressure within the melt sheet. For the injection of QD melt, the melt pressure exceeded the normal stress acting on fracture surfaces. For the later refracturing of QD dykes and the injection of MIQD melt, the melt pressure increased further, exceeding the tensile strength of, and the normal stress acting on, QD dykes. We associate the melt pressure increase required for both injection episodes with degassing and devolatilization of cooling melt close to the roof. Within the hydraulically connected melt column, the related pressure increase was transmitted to the base of the melt sheet where QD and MIQD melt was extracted into dykes. Residual core to rim thermal gradients in the QD dykes produced tensile strength gradients, accounting for the typically central location of MIQD dykes within QD dykes.

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Section: Constraints On Thermal Evolution Of the Melt Sheetsupporting

confidence: 67%

“…Milkereit et al. () predicted higher temperatures in deeper footwall over long time periods (>1 Myr).…”

Section: Constraints On Thermal Evolution Of the Melt Sheetmentioning

confidence: 95%

“… Modeling by Milkereit et al. () only considered the cooling process beginning from melt liquidus temperatures, so does not consider effects of supraliquidus heat in their modeling. …”

Section: Constraints On Thermal Evolution Of the Melt Sheetmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiphase emplacement of impact melt sheet into the footwall: Offset dykes of the Sudbury Igneous Complex, Canada

Prevec

Büttner

2018

Meteorit & Planetary Scien

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“…), followed by seismic investigations (Bell ) and deep drilling (Kenkmann ; Stoeffler ). Geophysical methods have also been used to delineate older, more deformed impact structures, most notably Sudbury (Milkereit ).…”

Section: Introductionmentioning

confidence: 99%

The Bow City structure, southern Alberta, Canada: The deep roots of a complex impact structure?

Glombick

Schmitt

Xie

et al. 2014

Meteorit & Planetary Scien

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Abstract-Geological and geophysical evidence is presented for a newly discovered, probable remnant complex impact structure. The structure, located near Bow City, southern Alberta, has no obvious morphological expression at surface. The geometry of the structure in the shallow subsurface, mapped using downhole geophysical well logs, is a semicircular structural depression approximately 8 km in diameter with a semicircular uplifted central region. Detailed subsurface mapping revealed evidence of localized duplication of stratigraphic section in the central uplift area and omission of strata within the surrounding annular region. Field mapping of outcrop confirmed an inlier of older rocks present within the center of the structure. Evidence of deformation along the eastern margin of the central uplift includes thrust faulting, folding, and steeply dipping bedding. Normal faults were mapped along the northern margin of the annular region. Isopach maps reveal that structural thickening and thinning were accommodated primarily within the Belly River Group. Evidence from legacy 2-D seismic data is consistent with the subsurface mapping and reveals additional insight into the geometry of the structure, including a series of listric normal faults in the annular region and complex faulting within the central uplift. The absence of any ejecta blanket, breccia, suevite, or melt sheet (based on available data) is consistent with the Bow City structure being the remnant of a deeply eroded, complex impact structure. Accordingly, the Bow City structure may provide rare access and insight into zones of deformation remaining beneath an excavated transient crater in stratified siliciclastic target rocks.

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Uranium–lead zircon systematics in the Sudbury impact crater-fill: implications for target lithologies and crater evolution

Petrus

Kenny

Ayer

et al. 2015

JGS

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The Sudbury impact structure is one of only a few terrestrial impact craters capable of providing insight into large impact processes. However, despite more than a century of study, no consensus exists regarding its depths of excavation and melting. This study presents 3920 U–Pb zircon dates for target lithologies and the crater-fill as well as new Pb-isotope data for target lithologies in an attempt to further constrain these depths and understand the behaviour of zircon in large impacts. Only 1.5% of the crater-fill zircons have dates within uncertainty of the 1.85 Ga impact event, with most seeming to preserve their pre-impact U–Pb systematics. The preponderance of undisturbed zircon in the crater-fill suggests that this mineral is an effective means of tracing target lithologies in impact basins. A significant fraction of crater-fill zircon was dated between 2.50 and 2.61 Ga, which is negligible amongst known target lithologies, and therefore identifies previously unrecognized target rocks. The Pb-isotope systematics are compatible with the proposal that the 2.6 Ga rock represents typical mid- to lower-crustal basement and could have been an important contributor to the melt-sheet. The combined data argue against a shallow melting scenario. With regard to Hadean terrestrial zircon, the lesson from Sudbury is that zircon can be recycled through multiple large impact events and still preserve the age of the original crust. Supplementary materials: Sample information, trace element and Pb-isotope data for granitoid and gneiss feldspar, Pb modelling parameters, U–Pb zircon data, concordia diagrams and airborne radiometric images are available at http://www.geolsoc.org.uk/SUP18881 .

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Fracturing, thermal evolution and geophysical signature of the crater floor of a large impact structure: The case of the Sudbury Structure, Canada

Cited by 3 publications

References 0 publications

Multiphase emplacement of impact melt sheet into the footwall: Offset dykes of the Sudbury Igneous Complex, Canada

Multiphase emplacement of impact melt sheet into the footwall: Offset dykes of the Sudbury Igneous Complex, Canada

The Bow City structure, southern Alberta, Canada: The deep roots of a complex impact structure?

Uranium–lead zircon systematics in the Sudbury impact crater-fill: implications for target lithologies and crater evolution

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