Age and origin of fluorapatite-rich dyke from Baranec Mt. (Tatra Mts., Western Carpathians): a key to understanding of the post-orogenic processes and element mobility

作者：Gaweda Aleksandra^*; Szopa Krzysztof; Chew David; Klotzli Urs; Mueller Axel; Sikorska Magdalena; Pyka Paulina

来源：Geologica Carpathica, 2016, 67(5): 417-432.

DOI：10.1515/geoca-2016-0026

• dyke
• apatite
• U-Pb apatite age
• Tatra Mountains

On the southeastern slope of the Baranec Mount in the Western Tatra Mountains (Slovakia) an apatite-rich pegmatite-like segregation was found in the subvertical fault zone cutting metapelitic rocks. Two zones: felsic (F) and mafic (M) were found, differing in mineral assemblages and consequently in chemistry. Fluorapatite crystals yield a LA-ICP-MSU-Pb age of 328.6 +/- 2.4 Ma. A temperature decrease from 634 degrees C to 454 degrees C at a pressure around 500 to 400 MPa with oxygen fugacity increasing during crystallization are the possible conditions for formation of the pegmatite-like segregation, while secondary alterations took place in the temperature range of 340-320 degrees C. The Sr-Nd isotope composition of both apatite and whole rock point toward a crustal origin of the dike in question, suggesting partial melting of (P, F, H2O)-rich metasedimentary rocks during prolonged decompression of the Tatra Massif. The original partial melt (felsic component) was mixed with an external (F, H2O)- rich fluid, carrying Fe and Mg fluxed from more mafic metapelites and crystallizing as biotite and epidote in the mafic component of the dyke.

• 出版日期2016-10