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Titolo:
MULTIPLE AUTHIGENESIS OF K-FELDSPAR IN SANDSTONES - EVIDENCE FROM THECRETACEOUS AREADO FORMATION, SAO-FRANCISCO BASIN, CENTRAL BRAZIL
Autore:
DEROS LF; SGARBI GNC; MORAD S;
Indirizzi:
UPPSALA UNIV,INST EARTH SCI,NORBYVAGEN 18B S-75236 UPPSALA SWEDEN UNIV FED MINAS GERAIS,INST GEOSCI,DEPT GEOL BR-31270901 BELO HORIZONTMG BRAZIL UNIV FED RIO GRANDE SUL,INST GEOCIENCIAS BR-91500 PORTO ALEGRE RS BRAZIL
Titolo Testata:
Journal of sedimentary research. Section A, Sedimentary petrology and processes
fascicolo: 4, volume: 64, anno: 1994,
pagine: 778 - 787
SICI:
1073-130X(1994)64:4<778:MAOKIS>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
OLIGOCENE FRIO FORMATION; SOUTH TEXAS; ROCKS; DISSOLUTION; DIAGENESIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
L.F. Deros et al., "MULTIPLE AUTHIGENESIS OF K-FELDSPAR IN SANDSTONES - EVIDENCE FROM THECRETACEOUS AREADO FORMATION, SAO-FRANCISCO BASIN, CENTRAL BRAZIL", Journal of sedimentary research. Section A, Sedimentary petrology and processes, 64(4), 1994, pp. 778-787

Abstract

Abundant authigenic K-feldspar is present in continental sandstones of the Lower Cretaceous Areado Formation in Sao Francisco Basin, central Brazil. Feldspar authigenesis occurred in two major episodes. (1) Inthe Early Cretaceous K-feldspar precipitated as overgrowths, healing of microfractures, and replacement of detrital EC-feldspar and plagioclase at very shallow depths. Authigenesis was related to meteoric dissolution of detrital volcanic feldspars, volcanic vitric rock fragments, and micas in a hot semiarid climate. (2) In the Late Cretaceous, while still at shallow depths, K-feldspar precipitated as abundant fine crystals associated with opal-CT, hematite, and mixed-layer illite/smectite. The feldspar has extensively filled the intergranular and, to a lesser extent, intragranular pores, and replaced mud intraclasts and volcanic rock fragments. The authigenesis in this second episode was related to percolation of meteoric waters through the overlying Upper Cretaceous alkaline volcanic racks of the Mata da Corda Formation, as indicated by the delta(18)O(SMOW) of K-feldspars from 19.4 to 21.8 partsper thousand.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/12/20 alle ore 10:31:36