TY - JOUR
T1 - Investigating the response of biotite to impact metamorphism
T2 - Examples from the Steen River impact structure, Canada
AU - Walton, E. L.
AU - Sharp, Thomas
AU - Hu, J.
AU - Tschauner, O.
N1 - Funding Information:
This work was funded by the Natural Science and Engineering Research Council Discovery Grant RES0007057 awarded to E. Walton. T. Sharp and J. Hu acknowledge NASA Cosmochemistry NNH08ZDA001N-COS Grant NNX09AG41G for supporting TEM analyses. We gratefully acknowledge the use of the FIB/TEM facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University. Thanks to Andrew Locock and Martin von Dollen at the University of Alberta for expertise in EMP and sample preparation, respectively. Rob Natyshen, Gordon Jean, and Diane Goulet at the Mineral Core Research Facility and Tyler Hauck (Alberta Geological Survey) are thanked for their assistance with core sampling. Synchrotron micro-XRD analyses were performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation—Earth Sciences (EAR-1128799) and Department of Energy-GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Beamline scientists Matt Newvill and Antony Lanzirolli are thanked for their assistance. The authors thank Yang Liu and Ludovic Ferrière for their constructive reviews, as well as comments from the Associate Editor Uwe Reimold, which improved the quality of this manuscript.
Funding Information:
Acknowledgments—This work was funded by the Natural Science and Engineering Research Council Discovery Grant RES0007057 awarded to E. Walton. T. Sharp and J. Hu acknowledge NASA Cosmochemistry NNH08 ZDA001N-COS Grant NNX09AG41G for supporting TEM analyses. We gratefully acknowledge the use of the FIB/TEM facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University. Thanks to Andrew Locock and Martin von Dollen at the University of Alberta for expertise in EMP and sample preparation, respectively. Rob Natyshen, Gordon Jean, and Diane Goulet at the Mineral Core Research Facility and Tyler Hauck (Alberta Geological Survey) are thanked for their assistance with core sampling. Synchrotron micro-XRD analyses were performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation—Earth Sciences (EAR-1128799) and Department of Energy-GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Beamline scientists Matt Newvill and Antony Lanzirolli are thanked for their assistance. The authors thank Yang Liu and Ludovic Ferrière for their constructive reviews, as well as comments from the Associate Editor Uwe Reimold, which improved the quality of this manuscript.
Publisher Copyright:
© The Meteoritical Society, 2017.
PY - 2018/1
Y1 - 2018/1
N2 - Impact metamorphic effects from quartz and feldspar and to a lesser extent olivine and pyroxene have been studied in detail. Comparatively, studies documenting shock effects in other minerals, such as double chain inosilicates, phyllosilicates, carbonates, and sulfates, are lacking. In this study, we investigate impact metamorphism recorded in crystalline basement rocks from the Steen River impact structure (SRIS), a 25 km diameter complex crater in NW Alberta, Canada. An array of advanced analytical techniques was used to characterize the breakdown of biotite in two distinct settings: along the margins of localized regions of shock melting and within granitic target rocks entrained as clasts in a breccia. In response to elevated temperature gradients along shock vein margins, biotite transformed at high pressure to an almandine-Ca/Fe majorite-rich garnet with a density of 4.2 g cm−3. The shock-produced garnets are poikilitic, with oxide and silicate glass inclusions. Areas interstitial to garnets are vesiculated, in support of models for the formation of shock veins via oscillatory slip, with deformation continuing during pressure release. Biotite within granitic clasts entrained within the hot breccia matrix thermally decomposed at ambient pressure to produce a fine-grained mineral assemblage of orthopyroxene + sanidine + titanomagnetite. These minerals are aligned to the (001) cleavage plane of the original crystal. In this and previous work, the transformation of an inosilicate (pargasite) and a phyllosilicate (biotite) to form garnet, an easily identifiable, robust mineral, has been documented. We contend that in deeply eroded astroblemes, high-pressure minerals that form within or in the environs of shock veins may serve as one of the possibly few surviving indicators of impact metamorphism.
AB - Impact metamorphic effects from quartz and feldspar and to a lesser extent olivine and pyroxene have been studied in detail. Comparatively, studies documenting shock effects in other minerals, such as double chain inosilicates, phyllosilicates, carbonates, and sulfates, are lacking. In this study, we investigate impact metamorphism recorded in crystalline basement rocks from the Steen River impact structure (SRIS), a 25 km diameter complex crater in NW Alberta, Canada. An array of advanced analytical techniques was used to characterize the breakdown of biotite in two distinct settings: along the margins of localized regions of shock melting and within granitic target rocks entrained as clasts in a breccia. In response to elevated temperature gradients along shock vein margins, biotite transformed at high pressure to an almandine-Ca/Fe majorite-rich garnet with a density of 4.2 g cm−3. The shock-produced garnets are poikilitic, with oxide and silicate glass inclusions. Areas interstitial to garnets are vesiculated, in support of models for the formation of shock veins via oscillatory slip, with deformation continuing during pressure release. Biotite within granitic clasts entrained within the hot breccia matrix thermally decomposed at ambient pressure to produce a fine-grained mineral assemblage of orthopyroxene + sanidine + titanomagnetite. These minerals are aligned to the (001) cleavage plane of the original crystal. In this and previous work, the transformation of an inosilicate (pargasite) and a phyllosilicate (biotite) to form garnet, an easily identifiable, robust mineral, has been documented. We contend that in deeply eroded astroblemes, high-pressure minerals that form within or in the environs of shock veins may serve as one of the possibly few surviving indicators of impact metamorphism.
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U2 - 10.1111/maps.13011
DO - 10.1111/maps.13011
M3 - Article
AN - SCOPUS:85040738924
SN - 1086-9379
VL - 53
SP - 75
EP - 92
JO - Meteoritics and Planetary Science
JF - Meteoritics and Planetary Science
IS - 1
ER -