Principal component analysis (PCA) and mineral associations of litoraneous facies of continental shelf carbonates from northeastern Brazil |
| |
Authors: | Wanessa Sousa Marques Alcides Nobrega Sial Eldemar de Albuquerque Menor Valderez Pinto Ferreira George Satander Sá Freire Enjolras de Albuquerque Medeiros Lima Valdir do Amaral Vaz Manso |
| |
Institution: | 1. NEG-LABISE, Department of Geology, Federal University of Pernambuco, C.P. 7852, Recife, Pernambuco, Brazil 50670-000, Brazil;2. DEGEO, Department of Geology, Federal University of Ceará, C.P. 6011, Fortaleza, Ceará 60455-970, Brazil;3. Geological Survey of Brazil (CPRM), Av. Sul 2291, Afogados, Recife, Pernambuco, Brazil 50770-011, Brazil |
| |
Abstract: | The distribution of mineral phases according to the provenance of carbonate and terrigenous facies of carbonate sediments from a large area of the continental shelf of northeast Brazil was investigated using a major element multivariate analysis approach. Heavy minerals such as ilmenite are restricted to the litoraneous facies of the continental shelf of the states of Paraíba and Pernambuco, and clay minerals are found in distal facies of the continental shelf of the State of Ceará. In the carbonate fraction, composed essentially by Mg-calcite and aragonite, there is co-variation between CaO/MgO and bathimetry in part of the studied continental shelf from depths between 15 and 20 m, apparently due to influence of the seawater temperature, degree of oxygenation and luminosity. The terrigenous facies are mainly composed of quartz, clay minerals, K-feldspars and micro-micaceous minerals, having Fe and Ti oxide and hydroxide minerals as major accessory phases. Major element behavior attests to the presence of arenaceous quartz-rich relict sediments in the 35, 60 and 80 m isobaths of the continental shelf of the state of Ceará which is here interpreted as a proxy of ancient coast lines during the Flandrian transgression. |
| |
Keywords: | Carbonates Relict sediments Geochemical composition Continental shelf Northeastern Brazil Principal component analysis (PCA) |
本文献已被 ScienceDirect 等数据库收录! |
|