Cumulate origin and polybaric crystallization of Fe-Ti oxide ores in the Suwalki anorthosite, northeastern Poland

in Economic Geology (2009), 104

Ferro-potassic a-type granites and related rocks in NE Poland and S Lithuania: West of the East European Craton

in Precambrian Research (2003), 124(2-4), 305-326

The present study of monzodiorite, quartz monzodiorite, monzonite, quartz syenite, granodiorite, and rapakivi-like granite surrounding the Suwalki, Ketrzyn and Sejny anorthosite, norite and gabbro plutons ... [more ▼]

The present study of monzodiorite, quartz monzodiorite, monzonite, quartz syenite, granodiorite, and rapakivi-like granite surrounding the Suwalki, Ketrzyn and Sejny anorthosite, norite and gabbro plutons or forming separate bodies in northern Poland and southern Lithuania, has resulted in the recognition of a specific suite with AMCG affinity. The bodies belonging to the Mazury and Veisiejai complexes are aligned to E-W trending lineaments in southern Lithuania and northern Poland with a continuation through the Baltic Sea into south-central Sweden in the west and into NW Belarus in the east. The rocks of the suite form a continuous series ranging from 45 to 75% SiO2 with no indication of the classical Daly gap between mafic and felsic rocks. The Mazury and Veisiejai complexes chemically belong to the ferro-potassic alkali-calcic type of rocks and are comparable with the AMCG suite, e.g. in Rogaland, southern Norway. The most acidic varieties of the granitoids approach the classic rapakivi granites in their petrogenetic characteristics, elevated contents of incompatible elements and REE, and hence have A-type affinities. The granitoids are assigned to the 'Post-collisional Granite' field. The overall evolution from mafic to acidic rocks is characterized by well-defined trends which most probably represent a liquid line of descent. Fractional crystallization with or without assimilation and hybridization can account for the continuous evolution from mafic to acidic members. The formation of the suite is concentrated in the timespan covering almost 50 Myr from 1.55 to 1.5 Ga. The most felsic rocks yield ages of ca. 1.5 Ga, which are very similar to the Kabehai granites further east in southeastern Lithuania. Cooling and local mylonitization proceeded until 1.4 Ga (hornblende and biotite Ar-40/Ar-39 ages). The Mazury and Veisiejai complexes are new evidence that anorthosites and related rocks can be linked to large lithospheric discontinuities. A thick crust and a Moho offset on the recent EUROBRIDGE geophysical profiles could indicate that a slab of lower crustal rock has been melted under the Suwalki massif to produce the AMCG rocks. Recent structural and kinematic observations indicate predominating transpressional/compressional regimes. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

Petrology and geochemistry of rapakivi-type granites from the crystalline basement of NE Poland

in Geological Quarterly (2001), 45(1), 33-52

The collection of 80 rock samples coming from drillcores of 8 localities from the Mazury Complex (Polish part of the crystalline East European Craton) and representing different rock types from ... [more ▼]

The collection of 80 rock samples coming from drillcores of 8 localities from the Mazury Complex (Polish part of the crystalline East European Craton) and representing different rock types from monzodiorites to leucogranites, were studied for major, trace and REE elements by XRF and ICP-MS methods. The range in composition of investigating rocks varies from 46% to 76% SiO2 contents. All of them show similar REE distributions, what suggests that they are genetically linked. They also plot along a major trend with many similarities to the jotunitic liquid line of descent (LLD) defined in AMCG rocks from Rogaland (Norway). Each group of rocks has however its own characteristics considering specific elements, such as REE, Sr or Zr. [less ▲]