U-Pb zircon SHRIMP data from the Cana Brava layered complex: new constraints for the mafic-ultramafic intrusions of Northern Goias, Brazil

被引：8

作者：

Giovanardi, T. ^{[1
,2
]}

Girardi, V. A. V. ^{[1
]}

Correia, C. T. ^{[1
]}

Sinigoi, S. ^{[3
]}

Tassinari, C. C. G. ^{[1
]}

Mazzucchelli, M. ^{[2
]}

机构：

[1] Univ Sao Paulo, Inst Geociencias, Rua Lago 563,Cidade Univ, BR-05508900 Sao Paulo, Brazil

[2] Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol, I-41121 Modena, Italy

[3] Univ Trieste, Dipartimento Geosci, I-34128 Trieste, Italy

来源：

OPEN GEOSCIENCES | 2015年 / 7卷 / 01期

基金：

巴西圣保罗研究基金会;

关键词：

Cana Brava; Layered Complex; Geochemistry; Zircon; SHRIMP; NIQUELANDIA COMPLEX;

D O I：

10.1515/geo-2015-0015

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

The Cana Brava Complex is the northernmost and least well known layered intrusion of a discontinuous belt of mafic-ultramafic massifs within the Brasilia Belt, which also comprises theNiquelndia and Barro Alto complexes. Available geochronological data from a range of techniques (K/Ar, Ar/Ar, Rb/Sr, Sm/Nd and U/Pb) provide a range of possible ages (time span from 3.9 Ga to 450 Ma), hence a precise and reliable age for the Cana Brava Complex is still lacking. Also, preliminary isotopic and geochemical data of the Cana Brava Complex suggest a significant crustal contamination, which could have affected bulk-rock Sr and Nd systematics resulting in meaningless age determinations. In this paper, we present new U-Pb SHRIMP zircon analyses from four samples of different units of the Cana Brava Complexwhich suggest that the intrusion occurred during the Neoproterozoic, between 800 and 780 Ma, i.e. at the same age of Niquelndia. Discordant older Pb-206/U-238 ages are provided by inherited zircons, and match the age of the metamorphism of the embedding Palmeirpolis Sequence.

引用

页码：197 / 206

页数：10

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