PAN-AFRICAN REWORKED EARLY MIDDLE PROTEROZOIC CRUST IN NE AFRICA WEST OF THE NILE - SR AND ND ISOTOPE EVIDENCE

被引：73

作者：

HARMS, U ^{[1
]}

SCHANDELMEIER, H ^{[1
]}

DARBYSHIRE, DPF ^{[1
]}

机构：

[1] NERC,ISOTOPE GEOSCI LAB,KEYWORTH NG12 5GG,NOTTS,ENGLAND

来源：

JOURNAL OF THE GEOLOGICAL SOCIETY | 1990年 / 147卷

关键词：

D O I：

10.1144/gsjgs.147.5.0859

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Whole-rock Rb-Sr studies on six suites of highly metamorphosed basement rocks from southern Egypt and northern Sudan, west of the River Nile, yield Pan-African ages (562-918 Ma): these ages are interpreted as reset. Orthogneisses give Nd model ages of 1600 to 2600 Ma for their calc-alkaline plutonic precursors. A gneiss derived from sedimentary precursors gave a mean crustal residence age of 2200 Ma. A series of I-type, late-tectonic, granitoids were intruded during a period of uplift, erosion, and wrench faulting at 560-620 Ma. Geochemical characteristics and Nd model ages (1200-1700 Ma) indicate that these rocks were derived from a mixed source of juvenile Pan-African mantle material and older continental crust of mainly early/middle Proterozoic age. Negative epsilon-Nd(t) values for granitoid samples (-18.9 to - 5.3) show that the Pan-African episode in NE Africa, west of the Nile, involved considerable reworking of pre-existing crust.

引用

页码：859 / 872

页数：14

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