TY - JOUR

T1 - Eastern Laurentia in Rodinia

T2 - constraints from whole-rock Pb and U/Pb geochronology

AU - Loewy, Staci L.

AU - Connelly, James N.

AU - Dalziel, Ian W. D.

AU - Gower, Charles F.

N1 - Funding Information: This study was partially funded by NSF Grant EAR 94 18236. Additional support was provided by The University of Texas Geology Foundation, The University of Texas Institute of Latin American Studies, South Central Section of the Geological Society of America and the Tectonics Special Research Centre at the University of Western Australia. Field logistics greatly benefited from the assistance of Rio Tinto Mining and Exploration Limited in northern Chile, thanks to Alasdaire Pope, George Steele and Osvaldo Ponce. We thank Victor Ramos of Rio Tinto and Patrick Mickler for their invaluable assistance in the field, Kathryn Manser and Todd Housh for their assistance in the isotopic facilities, Lisa Gahagan for help with Rodinia reconstructions using PLATES and Eric North and Johnathan Bumgarner for their assistance with sample processing.

PY - 2003

Y1 - 2003

N2 - Whole-rock Pb isotopic signatures and U/Pb geochronology refute a Rodinian correlation of northeastern Laurentia and proto-Andean Amazonia. According to this previously proposed model, the Labrador-Scotland-Greenland Promontory (LSGP) of northeastern Laurentia collided with the proto-Andean margin of Amazonia, at the Arica Embayment, during the Grenville/Sunsás Orogeny (ca. 1.0 Ga). Links between the two margins were based upon the correlation of the LSGP with Arequipa-Antofalla Basement (AAB), a Proterozoic block along the proto-Andean margin of Amazonia adjacent to the Arica Embayment. Specifically, similarities in 1.8-1.0 Ga basement rocks in both regions suggested that the AAB was originally a piece of the LSGP. Furthermore, similarities in unique, post-collisional, but pre-rift, glacial sedimentary sequences also supported a link between the AAB and LSGP. Tests of these apparent similarities fail to support correlation of the AAB and the LSGP and, thus, eliminate a direct link between northeastern Laurentia and southwestern Amazonia in Rodinia. However, Pb isotopic compositions and U/Pb geochronology provide the basis for two new correlations, namely, (1) the ca. 1.3-1.0 Ga basement in the central and southern Appalachians may be an allochthonous block that was transferred to Laurentia from Amazonia at ca. 1.0 Ga, and (2) an allochthonous AAB may be a piece of the Kalahari Craton that was transferred to Amazonia at ca. 1.0 Ga. Based on these new correlations and a previously proposed Grenvillian connection between southern Laurentia (Llano) and Kalahari, we propose that Amazonia may have collided with a contiguous southeastern Laurentia/Kalahari margin at ca. 1.0 Ga.

AB - Whole-rock Pb isotopic signatures and U/Pb geochronology refute a Rodinian correlation of northeastern Laurentia and proto-Andean Amazonia. According to this previously proposed model, the Labrador-Scotland-Greenland Promontory (LSGP) of northeastern Laurentia collided with the proto-Andean margin of Amazonia, at the Arica Embayment, during the Grenville/Sunsás Orogeny (ca. 1.0 Ga). Links between the two margins were based upon the correlation of the LSGP with Arequipa-Antofalla Basement (AAB), a Proterozoic block along the proto-Andean margin of Amazonia adjacent to the Arica Embayment. Specifically, similarities in 1.8-1.0 Ga basement rocks in both regions suggested that the AAB was originally a piece of the LSGP. Furthermore, similarities in unique, post-collisional, but pre-rift, glacial sedimentary sequences also supported a link between the AAB and LSGP. Tests of these apparent similarities fail to support correlation of the AAB and the LSGP and, thus, eliminate a direct link between northeastern Laurentia and southwestern Amazonia in Rodinia. However, Pb isotopic compositions and U/Pb geochronology provide the basis for two new correlations, namely, (1) the ca. 1.3-1.0 Ga basement in the central and southern Appalachians may be an allochthonous block that was transferred to Laurentia from Amazonia at ca. 1.0 Ga, and (2) an allochthonous AAB may be a piece of the Kalahari Craton that was transferred to Amazonia at ca. 1.0 Ga. Based on these new correlations and a previously proposed Grenvillian connection between southern Laurentia (Llano) and Kalahari, we propose that Amazonia may have collided with a contiguous southeastern Laurentia/Kalahari margin at ca. 1.0 Ga.

KW - Amazonia

KW - Arequipa-Antofalla Basement

KW - Common lead

KW - Laurentia

KW - Rodinia

KW - U/Pb

U2 - 10.1016/S0040-1951(03)00338-X

DO - 10.1016/S0040-1951(03)00338-X

M3 - Journal article

AN - SCOPUS:0242658747

VL - 375

SP - 169

EP - 197

JO - Tectonophysics

JF - Tectonophysics

SN - 0040-1951

IS - 1-4

ER -