2024-03-28T15:20:23Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1291062017-09-21T09:41:10Zcom_10261_39226com_10261_8col_10261_39228
2016-02-16T08:03:32Z
urn:hdl:10261/129106
The continental assembly of SW Gondwana (Ediacaran to Cambrian): a synthesis
Casquet, César
Rapela, Carlos W.
Pankhurst, Robert J.
Baldo, Edgardo G.
Galindo, Carmen
Dahlquist, J.
Verdecchia, Sebastián O.
Murra, J. A.
Fanning, M.
SW Gondwana resulted from complex interplay between continental amalgamation and
dispersal between ~ 650 and 490 Ma. The main cratons involved were Laurentia, Amazonia–
MARA (Proterozoic Maz–Arequipa–Rio Apa, Casquet et al., 2012), Kalahari, Rio de la Plata
(RPC), Congo and East Antarctica (Mawson block). Several collisional orogenic belts resulted,
notably the East Africa–Antarctica, Brasiliano–Panafrican, Pampean–Saldania, and Ross–
Delamerian orogens.
East-Antarctica broke away from the western margin of Laurentia in Rodinia. After a long drift
and counter-clockwise rotation (Dalziel, 2013) it collided with Congo and Kalahari to produce
the southern part of the left-lateral transpressional East Africa–Antarctica orogen between
580 and 550 Ma, completing the amalgamation of East Gondwana. The Trans-Antarctic
margin became an active one in the Ediacaran and subduction of the Pacific Ocean lithosphere
occurred throughout the Paleozoic, forming a tract of the Terra Australis orogen. NW–SE
directed compression in Late Cryogenian and Early Ediacaran times promoted closure of the
Adamastor Ocean, resulting in the left-lateral transpressional Brasiliano–Pan African orogeny
between 650 and 570 Ma.
The Pampean orogenic belt to the west of the RPC resulted from right-lateral collision between
Laurentia and its eastern extension MARA on the one hand and Kalahari–RPC on the other.
Ocean opening started at ~ 630 Ma and subduction and further collision took place between
540 and 520 Ma, coeval with the northward drift of Laurentia (~ 540 Ma) away from MARA
and the consequent formation of the proto-Andean margin of Gondwana. The margins of the
intervening Puncoviscana ocean were covered by Laurentia-derived siliciclastic sediments and
carbonates on the MARA side between 630 and ~ 540 Ma (Rapela et al, 2014; this symposium),
and by the marine siliciclastic Puncoviscana Formation on the other. The latter formation,
deposited between a 570 and ~530 Ma, received input from large alluvial fans descending
from juvenile Mesoproterozoic and Neproterozoic sources (new Hf isotope evidence) largely
located in the southern East Africa–Antarctica orogen. The Pampean orogen extended into
the Saldania–Gariep orogen of southern South Africa (545–520 Ma) and was apparently
discordant to the earlier Brasiliano–Pan African orogen. In late-Early to late Cambrian times the
Pampean–Saldania realm evolved into a passive margin with siliciclastic platform sedimentation.
The Pampean-Saldania realm was separated from the active Trans-Antarctic margin of East
Antarctica by an inferred transform fault in Ediacaran to Cambrian times. Regional NW–SW
shortening in the Ediacaran became N–S directed in the Cambrian, suggesting a major plate
reorganization at this time.
2016-02-16T08:03:32Z
2016-02-16T08:03:32Z
2015-06-01
comunicación de congreso
Gondwana 15, North meets South : Abstracts book, p. 30.
http://hdl.handle.net/10261/129106
eng
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openAccess
CSIC-UCM - Instituto de Geociencias (IGEO)