第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議

Armstrong R.A.

Eglington B.

Grantham G.H.

Hokada T.

Ingram B.A.

Jackson. C.

Macey P.H.

Manhica V.

Roberts M.P.

Shiraishi K.

National Institute of Polar Research Repository

Neoproterozoic to Cambrian granitoids of northern Mozambiqueand Dronning Maud Land AntarcticaG.H. Grantham1, P.H. Macey,2 M.P. Roberts3, B.A. Ingram1, R.A. Armstrong4, B. Eglington5, T. Hokada6, K.Shiraishi 6 C. Jackson.7, V. Manhica 81 Council for Geoscience, Pretoria, South Africa, 2 Council for Geoscience, Bellville South Africa, 3 Council for Geoscience, Port Elizabeth, South Africa. 4RSES, ANU, Canberra, Australia.  5University of Saskatchewan, Saskatoon, Canada.  6NIPR, Tachikawa,Tokyo, Japan, 7 51 Saint David’s Road, Claremont, Cape Town, South Africa.  8 DNG, Maputo, Mozambique.Granitoid intrusions with ages between ~570Ma and ~490Ma are common in the southern Namuno and NampulaTerranes of northern Mozambique as well as western and central Dronning Maud Land. The granitoids havewidely varying compositions from per-aluminous andalusite-bearing varieties to metaluminous granodioritictypes. The latter types include charnockitic examples in central Dronning Maud Land however in northernMozambique, western Dronning Maud Land and eastern Dronning Maud Land (Sor Rondane) charnockiticvarieties are rare to absent. The chemistry of many of the intrusions are typical of A2 type granites which havebeen interpreted to be typical of granites generated in extensional settings or in areas which have involvedthickened crust in continental collision settings. The granites are typically late-synkinematic to post tectonic. InSor Rondane and western Dronning Maud Land, the granites intrude as shallowly inclined sheets locally formingconjugate sets as well as sheet-like plutons. Poor exposure in Mozambique does not permit insights into theirmorphologies except north of the Lurio Belt where ring complex intrusions are recognized. The geometry of theinclined sheets are consistent with contractional emplacement. Radiogenic isotope data and inherited zirconsfrom the intrusions in northern Mozambique and western Dronning Maud Land indicate genesis by partialmelting of the Mesoproterozoic gneiss basement and, locally adjacent to the Kalahari Craton, contributions fromthe Archaean Kalahari basement are recognized. The older inheritance is reflected in Sm/Nd, Rb/Sr whole rockdata and in xenocrystic zircon fractions. Intrusion of some of the granitoids are apparently synchronous with thedeposition of the sillimanite-bearing migmatitic Mecuburi Group sediments. Sillimanite genesis as aconsequence of depositional burial and partial melting would require ~4-6kb (~12-18kms) equivalent of burial.This thickness is not seen in the Mecuburi. The granitoids are interpreted to have been generated by heating inthe footwall of a mega nappe during amalgamation of North and South Gondwana.   

Neoproterozoic to Cambrian granitoids of northern Mozambique and Dronning Maud Land Antarctica.

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Neoproterozoic to Cambrian granitoids of northern Mozambique and Dronning Maud Land Antarctica.

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