Wilson Terrane

The boundary between the Terra-Nova-Bay area and the main part of the Wilson terrane is not defined because the Ross Orogen continues from southern Victoria Land through the Terra-Nova-Bay area into the Wilson Terrane of northern Victoria Land without discernible interruption. The Wilson Terrane extends from the Terra-Nova-Bay area north to the Oates Coast of Antarctica and is separated from the Bowers Terrane by the Lanterman fault zone in Fig. 4.2. The Wilson Terrane extends east across the Renifick Glacier and includes the Lanterman and Salamander ranges which form its eastern province.  

The basement rocks of the Wilson Terrane are well exposed in the Wilson Hills and in the Daniels Range of the USARP Mountains as well as in the Emlen Peaks, on Welcome Mountain, and at Mt. Southard (Gair et al. 1969 Sturm and Carryer 1970 Tessensohn et al. 1981). Even though these mountain ranges are located adjacent to the polar plateau, Archean and Paleoproterozoic granulites of the East Antarctic era-ton have not been recognized in the Wilson Terrane or anywhere else in northern Victoria Land. 

The stratigraphy of the basement rocks of the Wilson Terrane located west of the Rennick Glacier consists of six units identified in Table 4.2 Berg Group, Rennick Schist, Priestley Formation, Morozumi 

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The Ross Orogen of southern Victoria Land extends across the David Glacier into the southern part of the Wilson Terrane of northern Victoria Land. The geology of this part of the Transantarctic Mountains in Fig. 4.6... 

Fig. 4.6 The basement rocks of southern Victoria Land extend northward across the David Glacier into the Terra-Nova-Bay region of the Wilson Terrane of northern Victoria Land (NVL). The basement rocks of this region consist mainly of Granite Harbor Intrusives and of metasedimentary rocks of Neoproterozoic to Cambrian age. The rocks above the Kukri Peneplain are not shown (i.e., Beacon Supergroup, Ferrar Dolerite, and McMurdo Volcanics). This area contains several prominent mountains including Mt. Melbourne which is an extinct volcano of the Cenozoic McMurdo Volcanics (Adapted from Warren 1969 Gair et al. 1969 Skinner 1983)...

Fig. 4.8 Whole-rock Rb-Sr isochron of Granite Harbor Intrusives (GHI) of the Terra Nova batholith in the Deep Freeze Range and from Timber Peak, Ogden Heights, and Mt. Nansen in the Terra-Nova-Bay area of the Wilson Terrane. All of the samples of the GHI he close to the straight line that was fitted by linear least-squares regression. The slope (m = 0.00722569) yields a date of 507.0 7 Ma and an initial Sr/ Sr ratio of 0.71034 0.00022 (o ). A migmatite (x) that was intruded by the Mt. Abbott pluton in the Deep Freeze Range (Fig. 4.7) is either much older (about 820 Ma) or has a higher initial ration (0.72709) than the rocks that define the straight line in this diagram (Data from Armienti et al. 1990)...

The Priestley Formation, Rennick Schist, Morozumi Phylhte, and the Berg Group ocettr in different areas of the Wilson Terrane. Although aU four units appear to be of Neoproterozoic age and although their Uthologic compositions are similar, they have not been correlated with each other... 

In the next section, the geology of the Morozumi Range and of the Lanterman and Salamander Ranges will be discussed separately because their tectonic settings differ from that of the Daniels Range in the western province of the Wilson Terrane. 

Fig. 4.15 The Morozumi, Lanterman, and Salamander ranges extend from the western province of the Wilson Terrane across the Rennick Glacier to the Bowers and Robertson Bay Terranes. The principal lithologic units of the basement complex are iden-...

Fig. 4.16 The Granite Harbor Intrusives of the Morozumi Remge in the Wilson Terrane crystaUized between 510 and 520 Ma and then reached the blocking temperature of biotite and muscovite between 460 and 490 Ma after coofing for about 35 million years fiom 515 to 480 Ma (Data from Kreuzer et al. 1981, 1987)...

Fig. 4.19 The Bowers Terrane occupies the central area of northern Victoria Land flanked by the Wilson Terrane in the west and the Robertson Bay Terrane in the east The major rock types of this segment of the Transantarctic Mountains are identified by capital letters in alphabetical order A = Admiralty Intmsives, B = Beacon Supergroup, BT = Bowers Terrane, G = Granite Harbor Intrusives, P = Galhpoli Porphyries, R = Robertson Bay Group, W = Wilson Group. The Kirkpatrick Basalt has been onritted from this map for the sake of clarity and the Ferrar Dolerite sills are included with the Beacon Supergroup. The Lanterman and Salamander ranges constitute the eastern province of the Wilson Terrane (Adapted from Gair et al. 1969)...

The intrusion of the Admiralty plutons was accompanied by the eruption of porphyritic rhyolites at Gallipoli Heights (72°26 S, 163°48 E) in the southern Freyberg Mountains located in the eastern province of the Wilson Terrane in Fig. 4.19 (Gair et al. 1969). 

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... 

Fig. 4. 28 The Wilson Terrane of northern Victoria Land (NVL) contains three thrust faults which define a crustal block that was uplifted as a result of compression from the east. The plane of the Wilson Thrust (WT) dips west at about 30° while the Exile Thrust (ET) and the Lazarev Thrust (LT) dip east. The uplifted block includes the Wilson Hills and the Pomerantz Tableland. The compressive force that activated the thrust faults originated either from the westward subduction, or by the collision of suspect terranes (i.e., BT and RBD with the Wilson Terrane or both (Adapted from Adams 2006)...

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 ... 

Fig. 4.29 The Wilson Thrust (WT) and the Exile and Lazarev Thrusts (ET and LT, respectively) in the northern Wilson Terrane (Fig. 4.28) dip in opposite directions and thus carve out a wedge-shaped block of the crust of the Wilson Terrane. West-directed forces arising from subduction of oceanic crust illustrated in Fig. 4.27, or the collision of the Bowers Terrane (BT) and the Robertson Bay Terrane (RBT) with the Wilson Terrane caused the crustal block to be uplifted relative to the East Antarctic Craton (EAC) and the Bowers Terrane. As a result, high-grade metamorphic rocks of the Uplifted Block were thrust over folded metasedimentary rocks located east and west of the Uplifted Block (Adapted from FI ttmann and Kleinschmidt 1991)...

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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