Lower Wright Geology, Antarctica

Ellery, S

The basement geology of the Lower Wright Valley comprises metasediments of the Precambrian Koettlitz Group and the Paleozoic Granite Harbour Intrusives. fulding and foliation development accompanied metamorphism of the Koettlitz Group under amphibolite facies during DJ . The Koettlitz Group is cross-cut by orthogneisses which represent the oldest rocks of the Granite Harbour Intrusives. The Koettlitz Group and cross-cutting orthogneisses (collectively mapped as the "Metamorphic Suite") are intmded by the Denton Pluton. The Denton Pluton is an inhomogeneous granitoid as a result of internal magma mingling and m,i xing between granodiorite and monzodiorite end-members. Inhomogeneities have been modified by flow, giving the body its characteristic mesoscopic compositional banding. Ballooning of the Denton Pluton resulted in D2, which caused ductile bulk shortening perpendicular to the Demon Pluton-Metamorphic Suite contact. D2 strain is concentrated at the contact. Dz is followed by intrusion of microdiorite dykes and the Goodspeed Intrusives. The Goodspeed Intrusives are characterised by internal magma mingling relationships between granodiorite and monzodiorite end-members. The massive, quartz monzonitic Brownworth Pluton discordantly intmdes the Metamorphic Suite. The Brownworth Pluton is cross-cut by mafic monzonite and K-feldspar porphyry dykes, representing the youngest of the Granite Harbour Intmsives. The Granite Harbour Intmsives of the lower Wright Valley are calc-alkaline in composition, showing dominantly 1-type characteristics. The Metamorphic Suite orthogneisses, the Denton Pluton and the Goodspeed Intmsives are members of the Dry Valleys 1 suite, while the Brownworth Pluton belongs to the Dry Valleys 2 suite. The basement rocks are tmncated by the Kukri Peneplain. The peneplain is overlain by Beacon Supergroup scdiments, which are intmded by the F-crrar Dolerite.

1989Ellery

POLYGON ((162.571153833217721 -77.522111972568808,162.544756646548734 -77.524689520214082,162.533800629334593 -77.522457541255235,162.471161003573997 -77.50967284007821,162.46440863076603 -77.508292278358468,162.385573624600795 -77.492139243185264,162.370683165140491 -77.48908103108333,162.27589761659317 -77.469560042576177,162.232277813477509 -77.460545205524184,162.264255861065976 -77.455731944874216,162.330503923037753 -77.445736765061852,162.350222150078423 -77.442755597297364,162.37712907552708 -77.438682999182959,162.425786401557787 -77.431304841191263,162.46229566612206 -77.429628024050359,162.466240995248569 -77.429446497595876,162.562472558859412 -77.424999314926694,162.622849518790645 -77.422189923284904,162.656613379439676 -77.429844498234189,162.704481704196638 -77.440673715434173,162.713837191459788 -77.442787059530247,162.767057500014573 -77.454789695233401,162.794429165351659 -77.460949868272635,162.775056606395822 -77.468856432108566,162.765585373173479 -77.472717866176254,162.74323799103513 -77.481818320935744,162.744132066395395 -77.482193403645766,162.764115331719154 -77.490570266505983,162.765550235837026 -77.491171288034394,162.788453670005538 -77.500755847177075,162.763067602286554 -77.503263499107376,162.714428359343032 -77.508058697167471,162.703131789878853 -77.50917062317518,162.592643439575369 -77.520010950190908,162.578690924342879 -77.521375350556369,162.571153833217721 -77.522111972568808))