Tectonics of the Wilson Terrane

The Wilson Hills and the Pomerantz Tableland in the northern Wilson Terrane contain the Wilson Thrust (WT) and the Exile Thrust (ET) as well as the Lazarev Thrust (LT), all of which strike north-northwest but dip in opposite directions. The Wilson Thrust in Eig. 4.28 

The hypothesis of Rottmann and Kleinschmidt (1991) was subsequently supported by Adams (2006) who demonstrated in Fig. 4.30 that the K-Ar dates of biotites in the Uplifted Block in Fig. 4.29 are significantly lower on average than K-Ar dates of slates and biotite in the adjacent part of the Wilson Terrane  

Evidently, the tectonic activity that was proposed by Flotttnann and Kleinschmidt (1991) can explain the significant losses of radiogenic °Ar from biotite in the Uplifted Block. 

The Ross Orogeny was presumably the culmination of the westward subduction of oceanic crust and of the overlying sediment that had previously accumulated along the paleo-Pacific coast of Gondwana. If the Ross Orogeny ended at about 490 4 Ma as implied by the data in Fig. 4.30, an explanation is needed for what triggered the westward compression of the Wilson 

Terrane that activated the thrust faults and caused the uplift of the crustal block defined by the Wilson Thrust and the Exile-Lazarev thrusts. Adams (2006) suggested that the uplift of the fault block was triggered by the collision of the Bowers and Robertson Bay terranes with the Wilson Terrane. This explanation supports the view that the Wilson Terrane formed by subduction and by the subsequent cratonization of a volcanic arc, whereas the Bowers Terrane and the Robertson Bay Terrane were added later by collisions of suspect terranes with Gondwana 

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