Development of kinematic partitioning within a pure-shear dominated dextral transpression zone: the southern Ellsworth Mountains, Antarctica

Abstract

The Heritage Range of the southern Ellsworth Mountains, West Antarctica, is Geological setting The Ellsworth Mountains form part of the Ellsworth-Whitmore Mountains block (EWM), CURTIS, M. L. 1998. Development of kinematic partitioning within a pure-shear dominated dextral transpression zone: the southern Ellsworth Mountains, Antarctica.

Detrital zircon provenance of upper Cambrian-Permian strata and tectonic evolution of the Ellsworth Mountains, West Antarctica

“…or along the orogenic strike. The twinned calcite preserves a layer-parallel shortening strain that is parallel to the Gondwanide thrust transport direction and consistent with the fold, cleavage and kinematic observations across the Ellsworth Mountains (Craddock et al 1992;Sporli and Craddock, 1992a,b;Curtis, 1997Curtis, , 1998Curtis, , 2001) and twinning strains reported from the upper Gondwana section in the Cape belt (Craddock et al 2007). Both limestones and vein calcite record a sub-vertical shortening strain (4 samples; see shortening axis stereonet inset in Fig.…”

“…The Cape Fold Belt of Africa (DuToit, 1937;Halbich, 1982), the Sierra de la Ventana Mountains in Argentina (Von Gosen et al 1987;Cobbold et al 1991), the Falkland archipelago and the Ellsworth Mountains (Craddock, 1983;Webers et al 1992) were all segments of one late Proterozoic-Paleozoic margin deformed in the early Permo-Triassic Gondwanide orogen (De Wit and Ransome, 1992). The preferred Gondwanide location of the EWT is ~90°clockwise from its present location (Watts and Brammall, 1981;Randall and Mac Niocaill, 2004; Cambrian paleopole solutions) in proximity to the Pensacola Mountains and the Argentina Range that lie in the Weddell Sea sector of the Transantarctic Mountains, a location that aligns all structural elements (Curtis, 1997(Curtis, , 1998(Curtis, , 2001. When the EWT diverged from Gondwana, the process included a bimodal igneous suite including pervasive Jurassic mafic intrusions (e.g.,…”

“…Thrusts dip to the WSW and hangingwall motions are up and to the ENE (Sporli et al 1992;Craddock et al 1992;Curtis, 2001) and a layer-parallel shortening strain is present in the Cambrian Minaret carbonates (Craddock et al 1997). Folds are overturned to the ENE and an axial planar cleavage is present; foliation-bound kinematics also indicate top-to-the-ENE motion (Curtis, 1997(Curtis, , 1998(Curtis, , 2001 in rocks that reached greenschist facies metamorphic grade (Bauer, 1992). The Cambrian Minaret Formation carbonates host a 3-phase carbonate breccia body formation that was contemporaneous with the Gondwanide orogen and is seemingly unique to this thrust belt (Sporli et al 1992;Craddock et al 2008).…”

The anatomy of a deep intracontinental orogen

“…However, careful field observations at Spaghetti Hill and Heather's Hill (Figures 2 and 3) indicate that N/S plunging lineations are hosted within shear zones that also contain exclusively top‐to‐the‐SW kinematics, with evidence of their gradual rotation to oblique orientations rather than truncation or superposition. Furthermore, their rotation can be correlated with distinct strain gradients, suggesting that they developed simultaneously in response to progressive strain partitioning (Figure 11) [ Curtis , 1998; Bailey et al , 2004; Pereira and Silva , 2004]. High‐strain zones are dominated by simple shear, and feature rotational kinematics and elongation lineations parallel to the bulk shearing vector (NE/SW).…”

Palaeozoic to Mesozoic polyphase deformation of the Patuxent Range, Pensacola Mountains, Antarctica

“…In both areas, the respective deformation events appear to have induced the most intense strain in rocks of Middle to Late Cambrian age (rocks that were unaffected by the early Ross deformation), where pre-existing end Cambrian age folds possess little or no coeval cleavage are superimposed by a regional penetrative cleavage. Recent studies from other segments of the GondwanianOrogensuggest that this Permianage deformation event was at least partly the result of dextral transpression within a wide, compressional back-arc setting (Curtis 1998, Rossello et al 1997, Trouw & DeWit 1999. Such a tectonic setting would be consistent with anti-clockwise cleavage transection of the F, fold observed at Snake Ridge.…”