Paleomagnetism of the Pandurra Formation and Blue Range Beds, Gawler Craton, South Australia, and the Australian Mesoproterozoic apparent polar wander path

被引:10
作者
Schmidt, P. W. [1 ]
Williams, G. E. [2 ]
机构
[1] CSIRO Earth Sci & Resource Engn, N Ryde, NSW 1670, Australia
[2] Univ Adelaide, Sch Earth & Environm Sci, Discipline Geol & Geophys, Adelaide, SA 5005, Australia
关键词
South Australia; Gawler Craton; Mesoproterozoic; red beds; paleomagnetism; polar wander; WESTERN-AUSTRALIA; PILBARA CRATON; GEOCHRONOLOGY; BASIN; STRATIGRAPHY; GLACIATION; MAGMATISM; REVERSAL; RODINIA;
D O I
10.1080/08120099.2011.570377
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The Mesoproterozoic Pandurra Formation and Blue Range Beds of the Gawler Craton, South Australia, are undeformed, low-dipping (typically 10-15 degrees) arenites of fluvial origin displaying pale to moderate red colours with light grey mottles and streaks and local Liesegang banding. Eighty-nine core samples and seven block samples were collected from 18 sites in the Pandurra Formation at Whyalla and 70 core samples from 16 sites in the Blue Range Beds at Talia. Specimens from all samples were stepwise thermally demagnetised, revealing hematite as the dominant magnetic carrier with a Neel temperature of 680 degrees C. The mean direction for the Pandurra Formation after tilt-correction (N=90 specimens) is declination=248.2 degrees, inclination=46.7 degrees (95=4.4 degrees), indicating a paleolatitude of 27.9+3.9/-3.4 degrees and a pole position at latitude 33.6 degrees S, longitude 64.5 degrees E (A 95=4.9 degrees). The mean direction for the Blue Range Beds after tilt-correction (N=61) is declination=233.9 degrees, inclination=50.2 degrees (95=4.0 degrees), with a paleolatitude of 31.0+3.7/-3.5 degrees and a pole position at 45.2 degrees S, 59.0 degrees E (A 95=4.7 degrees). Combined results for the two units after tilt-correction (N=151) is declination=242.6 degrees, inclination=48.3 degrees (95=3.1 degrees), indicating a mean paleolatitude of 29.3 +/- 2.8 degrees and a mean pole position at 38.4 degrees S, 62.4 degrees E (A 95=3.5 degrees). The combined results constitute a positive fold-test with 99% confidence, suggesting that the magnetisation pre-dates tilting. The two pole positions, when compared with Australia's Mesoproterozoic apparent polar wander path, imply ages between 1.5 and 1.2 Ga, in accord with the inferred stratigraphic ages. The pole paths for Australia and North America are sub-parallel from about 1.4 to 1.2 Ga, before diverging. However, during this interval Australia and North America were widely separated, seemingly ruling out their assemblage in some supercontinental reconstruction for that interval.
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页码:347 / 360
页数:14
相关论文
共 42 条
  • [1] [Anonymous], 2003, GEOL SOC AM ABSTR
  • [2] [Anonymous], 2001, MESA J
  • [3] BUCHAN KL, 1990, INT GEOL C, P209
  • [4] Butler R.F., 1992, Paleomagnetism: Magnetic domains to geologic terranes
  • [5] Chamalaun F. H., 1978, J GEOL SOC AUST, V25, P255, DOI [10.1080/00167617808729034, DOI 10.1080/00167617808729034]
  • [6] Collinson D.W., 1983, METHODS ROCK MAGNETI
  • [7] COWLEY WM, 1993, GEOL SURV S AUST B, V54, P139
  • [8] U-PB GEOCHRONOLOGY OF MIDDLE PROTEROZOIC FELSIC MAGMATISM SURROUNDING THE OLYMPIC DAM CU-U-AU-AG AND MOONTA CU-AU-AG DEPOSITS, SOUTH AUSTRALIA
    CREASER, RA
    COOPER, JA
    [J]. ECONOMIC GEOLOGY AND THE BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS, 1993, 88 (01): : 186 - 197
  • [9] Fanning C.M., 1983, Geological Survey of South Australia, V88, P11
  • [10] REFINED PROTEROZOIC EVOLUTION OF THE GAWLER CRATON, SOUTH-AUSTRALIA, THROUGH U-PB ZIRCON GEOCHRONOLOGY
    FANNING, CM
    FLINT, RB
    PARKER, AJ
    LUDWIG, KR
    BLISSETT, AH
    [J]. PRECAMBRIAN RESEARCH, 1988, 40-1 : 363 - 386