Premium
The north‐eastern Polish anorthosite massifs: petrological, geochemical and isotopic evidence for a crustal derivation
Author(s) -
Wiszniewska Janina,
Claesson Stefan,
Stein Holly,
Auwera Jacqueline Vander,
Duchesne JeanClair
Publication year - 2002
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2002.00443.x
Subject(s) - anorthosite , geology , geochemistry , massif , crust , mafic , basalt , isochron dating , archean , layered intrusion , magma , petrology , plagioclase , isochron , paleontology , volcano , quartz
Deeply buried 1.5 Ga Polish anorthosites, accessible only by bore holes, reveal diagnostic features of some massif‐type anorthosites (polybarism, jotunitic parent magma), diapirically emplaced in the mid crust together with the rapakivi granites of the EW‐trending Mazury complex, intruded along a major crustal discontinuity. Geochemical modelling and isotope data corroborate recent experimental work on the basaltic system in dry conditions: the source rock of the parental magma is a gabbronorite, necessarily lying in the lower crust. Since no Archaean crust is known in the region, high initial 188 Os/ 187 Os ratios for sulphide‐oxide isochrons and negative ε Nd values are best accounted for by melting a ∼ 2.0 Ga mafic crust.