Abstract Cooling subvolcanic igneous intrusions are known to have a tremendous impact on fluid flow in the shallow Earth's crust. However, the long-term post-cooling legacy of subvolcanic intrusions on fluid flow has received much less attention. Here we describe geological examples in the Andean foothills, Argentina, showing that igneous intrusions have long-term effects on fluid flow after their emplacement and cooling. The case study consists of ∼11 Myr-old eroded andesitic intrusions of Cerro Alquitrán and Cerro La Paloma, northern Neuquén Basin, Argentina, at the rims of which large volumes of bitumen are naturally seeping out at the Earth's surface. The intrusions exhibit laccolithic shapes with steep-sided contacts with the host rock. Near the intrusive contacts, the andesite is intensely broken along concentric breccia bands and fracture bands, interpreted as resulting from syn-emplacement brittle magma deformation, which represent high-permeability pathways for the migrating bitumen. Organic geochemical analyses of the bitumen show that the seeping oils were generated from incipiently mature Vaca Muerta sections located in a regional kitchen to the west, implying a lateral migration of ∼10–20 km. The Cerro Alquitrán and Cerro La Paloma intrusions are demonstrative examples highlighting how extinct subvolcanic intrusions have long-term consequences for subsurface fluid circulations in sedimentary basins.

Abstract This report presents new field observations and geochronology (isotope-dilution thermal ionization mass spectrometry/ID-TIMS and secondary-ion mass spectrometry/SIMS) on an igneous complex and its country rocks in the Bodø area, northern Norway, traditionally interpreted to represent the (par)autochthonous crust of Baltica ( c. 1.8 Ga). Field observations however indicate that the rocks are allochthonous and comprise the uppermost tectonostratigraphic level in the area. The presence of a migmatitic megacrystic granite with an emplacement age of 946 Ma strongly supports such an interpretation and indicates that the Bratten–Landegode gneiss complex is exotic with respect to Baltica. The 946 Ma granite intrudes metasedimentary rocks. The rocks were metamorphosed in the Late Ordovician and intruded by granitic pegmatites and diorites at 430 and 427 Ma, respectively. The Bratten–Landegode gneiss complex shows a close correlation with Mesoproterozoic–Neoproterozoic rock complexes in the East Greenland Caledonides and we interpret it to be a Laurentian pre-Caledonian continental fragment. The discovery of Laurentian pre-Caledonian continental crust in the Uppermost Allochthon calls for a revision of the tectonostratigraphy of this part of the Caledonides and provides important constraints on the sequence of events on the Laurentian margin prior to continent–continent collision between Baltica and Laurentia as well as on intercontinental interactions during the Caledonian orogeny.