J 2020

Long-Lasting (65 Ma) Regionally Contrasting Late- to Post-Orogenic Variscan Mantle-derived Potassic Magmatism in the Bohemian Massif

KRMÍČEK, Lukáš, Rolf L. ROMER, Martin J. TIMMERMAN, Jaromír ULRYCH, Johannes GLODNY et. al.

Basic information

Original name

Long-Lasting (65 Ma) Regionally Contrasting Late- to Post-Orogenic Variscan Mantle-derived Potassic Magmatism in the Bohemian Massif

Authors

KRMÍČEK, Lukáš (203 Czech Republic), Rolf L. ROMER (756 Switzerland), Martin J. TIMMERMAN (528 Netherlands), Jaromír ULRYCH (203 Czech Republic), Johannes GLODNY (276 Germany), Antonín PŘICHYSTAL (203 Czech Republic, guarantor, belonging to the institution) and Masafumi SUDO

Edition

Journal of Petrology, Oxford, Oxford University Press, 2020, 0022-3530

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10505 Geology

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

Impact factor

Impact factor: 4.515

RIV identification code

RIV/00216224:14310/20:00117734

Organization unit

Faculty of Science

DOI

UT WoS

000599223300007

Keywords in English

Ar-40/Ar-39 age determination; mantle melts; mantle metasomatism; lamprophyres; lampyrites; lamproites; Sr-Nd-Pb-Li isotopes

Tags

Tags

International impact, Reviewed
Změněno: 11/3/2021 09:54, Mgr. Marie Šípková, DiS.

Abstract

V originále

The orogenic development after the continental collision between Laurussia and Gondwana, led to two contrasting associations of mantle-derived magmatic rocks on the territory of the Bohemian Massif: (i) a 340-310Ma lamprophyre-lamproite orogenic association; and (ii) a 300-275Ma lamprophyre association of anorogenic affinity. Major types of potassic mantle-derived magmatic rocks recognized in the orogenic and anorogenic associations include: (i) calc-alkaline to alkaline lamprophyres; (ii) alkaline 'orthopyroxene minettes' and geochemically related rocks grouped here under the new term lampyrite; and (iii) peralkaline lamproites. These three types significantly differ with respect to mineral, whole-rock and Sr-Nd-Pb-Li isotope composition and spatial distribution. The calc-alkaline lamprophyres occur throughout the entire Saxo-Thuringian and Moldanubian zones, whereas the different types of malte-derived potassic rocks are spatially restricted to particular zones. Rocks of the Carboniferous lamprophyre-lamproite orogenic association are characterized by variable negative epsilon Nd-(i) and variably radiogenic Sr-(i), whereas the rocks of the Permian lamprophyre association of anorogenic affinity are characterized by positive epsilon Nd-(i) and relatively young depleted-mantle Nd-model ages reflecting increasing input from upwelling asthenospheric mantle. The small variation in the Pb isotopic composition of post-collisional potassic mantle-derived magmatic rocks (of both the orogenic and anorogenic series) implies that the Pb budget of the mantle beneath the Bohemian Massif is dominated by the same crust-derived material, which itself may include material derived from several sources. The source rocks of 'orthopyroxene minettes' are characterized by isotopically light ('eclogitic') Li and strongly radiogenic (crustal) Sr and may have been metasomatized by high-pressure fluids along the edge of a subduction zone. In contrast, the strongly Al2O3 and CaO depleted mantle source of the lamproites is characterized by isotopically heavy Li and high SiO2 and extreme K2O contents. This mantle source may have been metasomatized predominantly by melts. The mantle source of the lamprophyres may have undergone metasomatism by both fluids and melts.