Neoproterozoic ophiolite exotic blocks in the Outer Western Carpathians, southern Poland: a record of the fast ocean-floor cooling and alterations

Abstract

Ophiolitic blocks, rep re sented by metagabbro and ser pen tin ite con tain ing rel ict pyroxene, ol iv ine, baddeleyite, zirconolite, Ni-py rite and pyrrhotite, were found as ex otic blocks in an olistostrome in the Magura Nappe, Outer West ern Carpathians. The geo chem i cal and iso to pic fea tures of the blocks sug gest they rep re sent man tle-de rived rocks, with within-plate geochem is try sig na tures, mod i fied by subduction, with lithospheric man tle in put. A U-Pb ap a tite cool ing age (614 ±3 Ma) is within age un cer tainty of a pub lished U-Pb zir con mag matic crys tal li za tion age (~614 Ma) im ply ing rapid post-crys tal li za tion cool ing. Per va sive al ter ation with re place ment of pri mary min er als by low-tem per a ture as sem blages is ob served in all rock frag ments and is in ter preted as con tem po ra ne ous with shear ing. The sec ond ary min eral as sem blages and tem per a ture mod el ling al low the in ter pre ta tion that the per va sive ocean-floor meta mor phism is the al ter ation in these meta-mafic rocks. These ophiolitic frag ments can be linked to the Neoproterozoic break up of Rodinia/Pannotia.

Integrated subsurface characterisation of the Röt succession of the Bolesławiec Syncline (SW Poland): stratigraphic and tectonic constraints of the geological record

“…The new, completely cored boreholes provided abundant evidence of small-scale deformational structures in the Röt succession (Figs 3,4,6,9; see also Durkowski, 2022). These deformational structures belong to two distinct groups: 1) brittle-style deformational structures and 2) soft-sediment deformational structures.…”

“…Small-scale, foldstyle deformations occur locally along fault terminations (Figs 6B, 9I). Injection dykes occur commonly and have been observed in all of the new boreholes (Durkowski, 2022). They are accompanied locally by intraformational breccias (e.g., Fig.…”

“…Location of the study area. A. Simplified geological map without Cenozoic overburden of the North Sudetic Synclinoriun and adjoining areas (modified after Dadlez et al, 2000;Hielscher andHartsch, 2010 andDurkowski, 2022). Abbreviations: BS -Bolesławiec Syncline; ŚG -Świerzawa Graben; LHG -Leszczyna Half-Graben; LwHG -Lwówek Śląski Half-Graben; WG -Wleń Graben.…”

“…Abbreviations: BS -Bolesławiec Syncline; ŚG -Świerzawa Graben; LHG -Leszczyna Half-Graben; LwHG -Lwówek Śląski Half-Graben; WG -Wleń Graben. B. Simplified palaeogeography of the Germanic Basin in the Middle Triassic (modified after Ziegler, 1982;Matysik and Szulc, 2019;Durkowski, 2022). Abbreviations: KLFZ -Kraków-Lubliniec (Hamburg) Fault Zone; T-T Fault Zone -Teisseyre-Tornquist Fault Zone; SMF -Silesian-Moravian Fault; N -Triassic palaeolatitudes; NSS -North Sudetic Synclinorium; FSB -Fore-Sudetic Block.…”

“…The documentary material discussed here comes from cored intervals and corresponding geophysical wireline logs from several recently completed boreholes and is supported by palynological dating. One of the most striking observations concerns the abundance of diversified, small-scale, soft-sediment deformational structures within the Röt rocks (Durkowski, 2022). These rocks overlie a thick sandstone-siltstone succession of the local Buntsandstein facies, which is completely without similar deformational structures.…”