期刊
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
卷 16, 期 1, 页码 91-106出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/S0895-9811(03)00021-X
关键词
Gondwana margin; sedimentary geochemistry; siliciclastic rocks; upper Ordovician
Sandstone petrography, geochemistry (major, trace, and rare earth elements [REE]), and Nd isotopic composition are presented for the siliciclastic Lower Caradoc Pavon Formation of the San Rafael block, central west Argentina. These constrain the provenance and tectonic setting of deposition and enable comparison to equivalent Ordovician units along the proto-Andean Gondwana margin. Most of the Pavon Formation sandstones are quartz-feldspathic wackes, composed of quartz, feldspars, and fragments of metaquartzitic rocks. The samples plot in the recycled orogen and continental block provenance fields of QFL diagrams. In view of the intense recycling and diagenctic processes, as indicated by CIA and CIW indices, diagrams involving immobile trace elements are considered better source indicators and suggest an active margin and island continental arc provenance. REE element distributions and initial epsilonNd isotopic values (-3.1 to -4.0) provide evidence of upper crust source materials. Nd T-DM model ages for the provenance protolith are 1.4-1.5 Ga, consistent with a possible sediment source in Grenville-age rocks exposed in the Ponon Trehue area. The Pavon Formation was part of the sedimentary infill of a foreland basin generated and uplifted following accretion of the Precordillera terrane with the Gondwana active margin. (C) 2003 Elsevier Science Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据