Coeval Large-Scale Magmatism in the Kalahari and Laurentian Cratons During Rodinia Assembly

American Association for the Advancement of Science (AAAS) - Tập 304 Số 5674 - Trang 1126-1129 - 2004
Richard E. Hanson1,2,3,4,5, James L. Crowley1,1,3,4,5, Samuel A. Bowring1,1,3,4,5, Jahandar Ramezani1,1,3,4,5, W. A. Gose1,3,4,5, Ian W. D. Dalziel3,4,5, James A. Pancake1,2,3,4,5, Emily K. Seidel1,2,3,4,5, Thomas G. Blenkinsop6,1,3,4,5, Joshua Mukwakwami1,7,3,4,5
1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge MA 02139, USA,
2Department of Geology, Texas Christian University, Fort Worth, TX 76129, USA
3EG&G Technical Services, Inc., Morgantown, WV 26505, USA.
4Institute for Geophysics and Department of Geological Sciences, University of Texas, Austin, TX 78759, USA.
5Tectonics Special Research Centre, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia.
6Department of Earth Science, James Cook University, Townsville, QLD4811, Australia.
7Department of Geology, University of Zimbabwe, Post Office Box MP 167, Harare, Zimbabwe.

Tóm tắt

We show that intraplate magmatism occurred 1106 to 1112 million years ago over an area of two million square kilometers within the Kalahari craton of southern Africa, during the same magnetic polarity chron as voluminous magmatism within the cratonic core of North America. These contemporaneous magmatic events occurred while the Rodinia supercontinent was being assembled and are inferred to be parts of a single large igneous province emplaced across the two cratons. Widespread intraplate magmatism during Rodinia assembly shows that mantle upwellings required to generate such provinces may occur independently of the supercontinent cycle.

Từ khóa


Tài liệu tham khảo

10.1126/science.246.4926.103

10.1016/S1631-0713(03)00006-3

R. E. Ernst, K. L. Buchan, Geol. Soc. Am. Spec. Pap.352, 483 (2001).

10.1029/JZ069i012p02465

H. L. Allsopp, J. D. Kramers, D. L. Jones, A. J. Erlank, S. Afr. J. Geol.92, 11 (1989).

10.1130/0091-7613(1998)026<1143:UPZAFT>2.3.CO;2

10.1016/S0899-5362(99)00009-3

10.1016/0301-9268(95)80008-6

10.1111/j.1365-246X.1966.tb03065.x

10.1017/S001675689800123X

10.1016/S0899-5362(00)00046-4

Materials and methods are available as supporting material on Science Online.

Age uncertainties are stated at the 2σ level. For sample 96-141 ( 12 ) in eastern Zimbabwe Hanson et al . ( 6 ) reported U-Pb zircon isotopic analyses that were 1.9 to 17.9% discordant. They inferred that the 207 Pb/ 206 Pb date for the most concordant grain (1104.7 ± 2.3 Ma) provided the best estimate of the age of the sill. This result is superseded by new analyses reported in fig. S4 and table S2 which yield a weighted mean 207 Pb/ 206 Pb date of 1109.6 ± 0.6 Ma (Fig. 1).

10.1139/e17-039

D. J. Allen, W. J. Hinze, A. B. Dickas, M. G. Mudrey Jr., Geol. Soc. Am. Spec. Pap.312, 47 (1997).

H. C. Halls, L. J. Pesonen, Geol. Soc. Am. Mem.156, 173 (1982).

10.1016/S0009-2541(02)00074-8

L. L. Shastri, K. R. Chamberlain, S. A. Bowring, Geol. Soc. Am. Abstr. Program23, 93 (1991).

10.1130/0091-7613(1992)020<0637:GDSITP>2.3.CO;2

S. A. Bowring unpublished data.

10.1139/e93-122

10.1016/S0040-1951(03)00339-1

10.1126/science.252.5011.1409

10.1144/GSL.SP.2003.206.01.04

10.1016/S0301-9268(01)00178-4

10.1016/S0040-1951(03)00342-1

10.1086/314418

In the absence of an independent polarity constraint the near-zero inclination of the Umkondo magnetization direction resulting from the equatorial position of Kalahari ∼1100 Ma permits either polarity assignment and makes it possible to rotate Kalahari by 180° without shifting its latitudinal position.

10.1016/S0012-821X(00)00061-3

10.1130/G20171.1

10.1038/332695a0

10.1029/95JB02518

10.1130/0091-7613(1994)022<0039:SOS>2.3.CO;2

10.1126/science.1065448

10.1016/S0012-821X(98)00089-2

10.1007/BF00310744

10.1139/e17-044

10.1016/S0899-5362(02)00011-8

10.1144/GSL.SP.2003.206.01.20

10.1144/GSL.SP.2003.206.01.13

10.1016/S0301-9268(02)00201-2

10.1016/S0899-5362(00)00040-3

M. O. Schwartz, Y. Y. Kwok, D. W. Davis, P. Akanyang, S. Afr. J. Geol.99, 245 (1996).

N. Pfurr, H. Ahrendt, B. T. Hansen, K. Weber, Communs. Geol. Surv. Namibia7, 35 (1991).

10.2113/104.1.13

W. R. Van Schmus, M. W. Martin, D. R. Sprowl, J. Geissman, P. Berendsen, Geol. Soc. Am. Abstr. Program22, A174 (1990).

For the Midcontinent rift we used the average of the published poles for the Logan sills Coldwell Complex Powder Mill Group and North Shore Volcanic Group ( 16 21 ) which have yielded U-Pb crystallization ages of 1107.9 ± 1.8 to 1108 ± 1 Ma ( 14 36 37 ). The position of this average pole is 49.1°N 209.2°E with a radius for the 95% circle of confidence of 7.7°. Aligning this pole and the mean Umkondo pole places the two cratons ∼3000 km apart. The separation could be decreased by ∼1700 km if the extreme limits of the error circles for the poles were used.

10.1130/0091-7613(1989)017<1049:GAGCOT>2.3.CO;2

J. F. Wilson, D. L. Jones, J. D. Kramers, Geol. Assoc. Can. Spec. Pap.34, 433 (1987).

10.1029/JZ071i002p00543

R. B. Hargraves, P. J. Hattingh, T. C. Onstott, S. Afr. J. Geol.97, 114 (1994).

M. Peters, Ber. Polarforschung61, 1 (1989).

10.1016/S0040-1951(03)00341-X

We thank G. Brandl for advice on sample sites in South Africa; T. Machacha (Director) and T. Majaule Botswana Geological Survey for permission to sample borehole cores from the Xade Complex; B. Vink and M. Wendorff for assistance in Botswana; F. Venter for permission to sample in Kruger National Park South Africa and J. Venter for assistance in the park; and A. Maloof for discussions of paleomagnetic data. Supported by NSF grant nos. EAR-9909269 (R.E.H.) and EAR-9909854 (I.W.D.D. and W.A.G.) and EAR-9526702 (S.A.B.) and by the Tectonics Special Research Centre University of Western Australia (I.W.D.D.). This paper is dedicated to the memory of H. Munyanyiwa who first pointed out to us the potential significance of the Umkondo sills in eastern Zimbabwe.

Thông tin
Thông tin xuất bản

American Association for the Advancement of Science (AAAS)

Tập 304 Số 5674

1126-1129

Thông tin tác giả