engleski

New data on igneous rocks in the Adriatic Sea: a possible indicator of the the Pangea Supercontinent disintegration

Occurrences of igneous rocks (mainly gabbro to diorite) on the Adriatic Sea islands are few- this research focuses on two known igneous islands (Jabuka and Brusnik) and on a previously unknown underwater shoal locality (Brusnik Shoal). All three localities are part of the Adriatic microplate that hosts the Mesozoic Adriatic Dinaridic Carbonate Platform (ADCP) and is mostly comprised of carbonates. Previously published K- 40-Ar-40 (Balogh et al., 1994, Geologia (Bologna), 56, 13-25) and Ar-40-Ar-39 ages (Palinkas et al., 2010, Acta Mineralogica-Petrographica, 8, 1-15) constrain the emplacement of gabbroitic rocks in ADCP to 276-200 Ma. The Central Atlantic Magmatic Province (CAMP) formed 200 Ma ago (Blackburn et al., 2013, Science, 340, 6135, 941-945) during the rifting of the supercontinent Pangea, whilst the Adriatic microplate migrated northward through the Tethys Ocean. Sedimentation on the ADCP continued and covered the igneous rocks with a thick succession of Mesozoic limestone. We determined that the major and trace element signature of the gabbros indicate a non-primitive parental magma in an active continental marginal setting with significant contribution from a recycled continental crust Considering the wide age data ranging from 276-200 Ma, question arises whether these occurrences of igneous rocks in the Adriatic Sea are connected to CAMP due to their past vicinity and could they be a remnant of the initial stages of disintegration of the supercontinent Pangea. If so, these rare localities with in the Adriatic Sea could be the easternmost occurrences of CAMP-like rocks and possibly an important source of information about the initial processes that accompanied the disintegration of Pangea. Geochemical data from previously published work and the new geochemical data were compared to Moroccan gabbros related to CAMP (Bensalah et al., 2011, Comunicacoes Geologicas, 98, 15-27) indicating a plausible connection. Mineral chemistry of orthopyroxene, clinopyroxene, magnetite, ilmenite, amphibole, plagioclase and prehnite together with microstructural relations observed on BSE images reveal a complex set of syn- to post-kinematic reactions inside igneous body and preliminary constrain its temperature evolution and emplacement depth in accordance with scarce field observations.

Jabuka ; Brusnik ; igneous rocks ; gabbroic rocks ; CAMP

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