Mulder, J and Karlstrom, K and Halpin, J and Meffre, S and Gehrels, G and Pecha, M, Correlating the Late Mesoproterozoic Unkar Group, Grand Canyon, Arizona with the upper Rocky Cape Group, western Tasmania: a sedimentary record of a southwest Laurentia-East Antarctica connection in Rodinia, Geophysical Research Abstracts, 23-28 April, Vienna, Austria, pp. 10810. ISSN 1607-7962 (2017) [Conference Extract]
The stratigraphy of the Unkar Group and upper Rocky Cape Group are remarkably similar with both successions comprising a lower subdivision of stromatolitic dolomite and siltstone overlain by quartz arenite with soft-sediment deformation features. Detrital zircons age distributions from the Unkar and upper Rocky Cape Groups are both characterized by large age peaks at 1600—1800 Ma, prominent 1450 Ma peaks, abundant 1400—1300 Ma ages, and youngest peaks at ca. 1220 Ma. The 1450 Ma zircons from the Unkar Group have initial epsilon Hf values (Hfi) of 3.76—12.95, comparable to Hfi values of 1.84—12.53 from 1450 Ma zircons from the upper Rocky Cape Group. The 1400—1300 Ma zircons from the Unkar Group have Hfi of 1.16—11.89, which is similar to time-equivalent grains from the upper Rocky Cape Group (Hfi = 1.33—12.47). The youngest zircons from the Unkar Group (1300—1200 Ma) have Hfi of -0.78—12.74 Ma, which generally overlap with the Hfi of 1300—1200 Ma zircons from the upper Rocky Cape Group, although the latter includes grains with Hfi as low as -6.26.
The age distribution and Hf isotopic composition of detrital zircons from the Unkar and upper Rocky Cape Groups are consistent with derivation from basement sources in southern Laurentia including the Grenville orogen. Correlation of the Unkar and upper Rocky Cape Groups is supported by similarities in stratigraphy and detrital zircon provenance and suggests western Tasmania formed part of the Late Mesoproterozoic basin system of southwest Laurentia. The close affinity of the Proterozoic geology of western Tasmania to the Transantarctic Mountains of East Antarctica indicates that the new correlations presented here support the interpretation that the Grenville orogen extended into the Transantarctic Mountains, implying a connection between southwest Laurentia and East Antarctica within Rodinia.
|Item Type:||Conference Extract|
|Keywords:||Tasmania, Rodinia, Laurentia, Rocky Cape Group, Grand Canyon|
|Research Division:||Earth Sciences|
|Research Field:||Structural geology and tectonics|
|Objective Division:||Expanding Knowledge|
|Objective Group:||Expanding knowledge|
|Objective Field:||Expanding knowledge in the earth sciences|
|UTAS Author:||Mulder, J (Mr Jacob Mulder)|
|UTAS Author:||Halpin, J (Dr Jacqueline Halpin)|
|UTAS Author:||Meffre, S (Dr Sebastien Meffre)|
|Deposited By:||Oceans and Cryosphere|
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