| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Journal of Petrology Volume 42 Number 7 Pages 1373-1385 2001
© Oxford University Press 2001
Hercynian Metamorphism in Nappe Core Complexes of the Alpine Betic–Rif Belt, Western Mediterranean—a SHRIMP Zircon Study
1INSTITUTE FOR STUDY OF THE EARTH’S INTERIOR, MISASA, TOTTORI-KEN, JAPAN
2RESEARCH SCHOOL OF EARTH SCIENCES, THE AUSTRALIAN NATIONAL UNIVERSITY, CANBERRA, A.C.T. 0200, AUSTRALIA
Ion microprobe U–Pb dating of a bimodal zircon population from a graphitic schist from the basal section of the Alpine Alpujárride nappe complex in the Betic Cordilleras, southern Spain, has yielded different ages for zircons of contrasting morphology and composition. Approximately half the grains are rounded and abraded, and have ages ranging from 
2·2 Ga to 350 Ma. These are detrital grains from the schist’s sedimentary parent material, indicating its derivation from a composite basement and a Palaeozoic, possibly Carboniferous, age of deposition. The other half of the grains consist of euhedral cores of Hercynian age (305·3 ± 3·2 Ma) surrounded by Late Alpine (19·7 ± 2·2 Ma) metamorphic overgrowths (
= 0·05 errors). The Hercynian cores probably record the first, medium–high-grade amphibolite-facies metamorphism, relicts of which are seen in the schist complex, whereas the rims were formed during the final tectono-metamorphic stage in the Alpine development of the orogenic belt. The bimodality of the zircon population in age, morphology and internal structure may mainly reflect the lithological bimodality of the rock (thin quartzitic layers or schlieren alternating with graphitic micaceous folia) and the control that that exerted on fluid circulation in the metamorphic environment.
KEY WORDS: SHRIMP zircon ages; Alpine belt; Western Mediterranean; Betic–Rif; Hercynian–Alpine polymetamorphism
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  H. P. ZECK, M. T. D. WINGATE, G. D. POOLEY, and J. M. UGIDOS A Sequence of Pan-African and Hercynian Events Recorded in Zircons from an Orthogneiss from the Hercynian Belt of Western Central Iberia--an Ion Microprobe U-Pb Study J. Petrology, August 1, 2004; 45(8): 1613 - 1629. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. P. ZECK and I. S. WILLIAMS Inherited and Magmatic Zircon from Neogene Hoyazo Cordierite Dacite, SE Spain--Anatectic Source Rock Provenance and Magmatic Evolution: In Memoriam Professor Chris Powell, {dagger} 2001.07.21 J. Petrology, June 1, 2002; 43(6): 1089 - 1104. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Zeh, A. ZEH, H. BRATZ, I. L. MILLAR, and I. S. WILLIAMS A combined zircon SHRIMP and Sm-Nd isotope study of high-grade paragneisses from the Mid-German Crystalline Rise: evidence for northern Gondwanan and Grenvillian provenance Journal of the Geological Society, November 1, 2001; 158(6): 983 - 994. [Abstract] [Full Text] [PDF]
|
|