Brown Hills

However, Mortimer (1981) and Findlay et al. (1984) who also worked in the area did not agree with the stratigraphic sequence proposed by Blank et al. (1963). Mortimer (1981) concluded that the Salmon and Miers Marble were the same layer of rock and that the Garwood Lake and the Marshall Formation were also the same unit. Findlay et al. (1984) who remapped basement rocks throughout southern Victoria Land subdivided the Koettlitz Group into the Marshall Formation, the Salmon Marble, and the Hobbs Formation but did not place them in stratigraphic order. 

Metasedimentary rocks which are common in the ice-free valleys and in the Koettlitz-Skelton Glacier areas occur in the Brown Hills only as scattered inclusions within the Carlyon Granodiorite in the form of dark quartz-biotite-homblende schist and light-colored metaquartzite. A large raft of metasediment, about 10,000 m in area, occurs in the valley between the 

Diamond Glacier and Lake Wilson on the coast of the Ross Ice Shelf in Fig. 3.12. The strike of the metasedimentary rocks and the foliation of the Carlyon Granodiorite are parallel and the contact between them is gradational. 

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Fig. 3.16 The " Ar/ Ar ratios of argon released by step-wise heating of a powdered sample of neutron-irradiated hornblende were used to calculate a series of dates which define a plateau at 534 6 Ma. This date is a reliable estimate of the crystallization age of the Carlyon Granodiorite in the Brown Hills, southern Victoria Land (Replotted from data by Felder and Faure 1990)...

More recently, Encamacion and Grunow (1996) reported a U-Pb date of 515 8 Ma for zircon in the equigranular and unfoliated granite of the Cooper Nunatak in the Brown Hills (see below). This date is compatible with the " ArP Ar dates of biotites and hornblende reported by Felder and Faure (1990) and further constrains the time of intrusion and crystallization of the granite plutons in the Brown Hills. 

The Ar/ Ar method of dating was used by Felder and Faure (1990) to determine the age of hornblende crystals from a sample of the Carlyon Granodiorite in the Brown Hills of southern Victoria Land. The spectrum of dates in Fig. 3.16 has a well-developed plateau that yields an average date of 534 6 Ma. 

Felder RP, Faure G (1980) Rubidium-strontium age determinations of part of the basement complex of the Brown Hills, central Transantarctic Mountains. Antarctic J US 15(5) 16-17... 

We now move south from the ice-free valleys and the Boomerang Range to the Darwin Mountains of southern Victoria Land adj acent to the Darwin and Hatherton glaciers and north of the Byrd Glacier in Fig. 10.8. This segment of the Transantarctic Mountains also includes the Brown Hills (Section 3.3) where granitic rocks of the local basement complex are exposed. 

Devonian Taylor Brown Hills Congl Kukri Unconformity... 

Devonian or Heights Arena Altar Mtn. Odin Arkose HeimdaU Disconformity Taylor New Mountain Brown Hills... 

Fig. 13.13 The Roadend Nunatak is located at the confluence of the Touchdown and Darwin glaciers close to Bastion Hill in the Brown Hills. This nunatak contains partial sections of the Basement siU and of the Peneplain sid. The Basement sill intruded the Hope Granite of the Granite Harbor Intrusives. " e Peneplain siU is underlain by a sliver of the Brown Hills...

Fig. 13.14 The rocks exposed on Roadend Nunatak consist of the Basement sill of the Ferrar Dolerite which intrudes the Hope Granite of the local basement complex. The Kukri Peneplain is overlain by a sliver of the Brown Hills Conglomerate of the Beacon Supergroup which was intruded by the Peneplain sill. The Roadend Nunatak is now capped by the Peneplain sill because the overlying Beacon rocks were eroded. This section was measured during the 1978/79 field season by G. Faure and R.P. Felder...

The geology of this part of the Transantarctic Mountains, described by Grindley and Laird (1969), consists of flat-lying quartz sandstones of the Beacon Supergroup that were intruded by sills of the Ferrar Dolerite. These rock units are underlain by the granitic basement rocks of the Granite Harbor Intrusives that are exposed in the Brown Hills along the coast of the... 

Ross Ice Shelf (Section 3.3). Haskell et al. (1963, 1965) mapped the granitic basement rocks and overlying Beacon rocks in the Brown Hills and Darwin Mountains, but they did not include Butcher Ridge in their study area. 

Fig 18 21 Derrick Peak at 80°04 S and 156°23 E is the site where a small group of iron meteorites was found by a team of New Zealand geologists. The principal meteorite-discovery site is outlined in red. The Hatherton Glacier is a southern tributary to the Darwin Glacier which flows between the Brown Hills and the Britannia Range before merging into the Ross Ice Shelf (Adapted from U.S.G.S. map SU 56-60/1, Mount Olympus, Antarctica with information from Shiraishi 1979)... 

Haskell TR, Kennett JP, Prebble WM (1965) Geology of the Brown Hills and Darwin Mountains, southern Victoria Land, Antarctica. Trans Roy Soc New Zealand Geology 2(15) 231-247... 

Faure G, Felder RP (1981) Isotopic composition of strontium and sulfur in secondary gypsum crystals. Brown Hills, Transantarctic Mountains. J Geochem Explor 14 ... 

S. Bruce Brown Hill Country Patent Services, Inc, Austin, TX, USA... 

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