Zircon dating ties NE Atlantic sill emplacement to initial Eocene global warming

<p>The Earth experienced rapid greenhouse gas induced global warming during the Palaeocene–Eocene thermal maximum (PETM). The source of the gas is, however, debated. We have, for the first time, determined the ages of magmatic sills in the Vøring Basin offshore Norway. Zircon U–Pb ages of 55.6 ± 0.3 and 56.3 ± 0.4 Ma demonstrate that sill emplacement was synchronous with the PETM within small errors. This discovery strengthens the hypothesis that global warming was triggered by rapid release of greenhouse gases generated by heating of organic-rich sediments around intrusions in the NE Atlantic rather than from dissociation of gas hydrates. </p

U–Pb zircon ages of Late Cretaceous Nain–Dehshir ophiolites, central Iran

<p>Late Cretaceous Zagros ophiolites are part of the <em>c</em>. 3000 km long Late Cretaceous Ophiolite Belt of SW Asia including the Troodos (Cyprus), eastern Mediterranean (Turkey, Syria), Zagros (Iran) and Semail ophiolites (Oman). This ophiolite belt represents a magmatic forearc that formed when subduction of the Neotethys began along the SW margin of Eurasia. Geochronological data for Zagros ophiolites are limited to a few K–Ar and ⁴⁰Ar–³⁹Ar ages. New thermal ionization mass spectrometry U–Pb zircon ages indicate that the Nain and Dehshir ophiolites of central Iran formed <em>c</em>. 101–103 Ma, with Nain (102.9 ± 0.3 Ma) being <em>c</em>. 1 Ma older than Dehshir (100.9 ± 0.2 Ma; 100.4 ± 0.1 Ma), and that these ophiolites were emplaced almost immediately after formation (Nain emplacement 101.2 ± 0.2 Ma; Dehshir emplacement 99.0 ± 1.1 Ma). These formation ages are significantly older than the 98–90 Ma U–Pb zircon ages of other Late Cretaceous ophiolites in this belt such as the Kizildag (Turkey), Semail (Oman) and Troodos ophiolites (Cyprus). If the subduction initiation model applies to this ophiolite belt, it suggests that subduction initiation began near the Zagros margin and propagated at <em>c</em>. 7 cm a⁻¹ to the east (Semail) and <em>c</em>. 15 cm a⁻¹ to the west (Troodos). </p

Age and origin of thin discontinuous gneiss sheets in the distal domain of the magma-poor hyperextended pre-Caledonian margin of Baltica, southern Norway

Fig. S1. Photomicrograph of the chlorite schist presented in Fig. 2e. Crossed polarizers. Note the unusually high number of minute zircon grains (indicated by red circles)

Mid-Ordovician stratigraphy and volcanism in the Hølonda area, Scandinavian Caledonides: complex tectonomagmatic development following arc–continent collision near the Laurentian margin of Iapetus

Figure S3. Extended mantle-normalized trace element diagrams

Mid-Ordovician stratigraphy and volcanism in the Hølonda area, Scandinavian Caledonides: complex tectonomagmatic development following arc–continent collision near the Laurentian margin of Iapetus

Table S1. Whole-rock geochemical data (Excel table), including isotopes

Visean high-K mafic-intermediate plutonic rocks of the Ossa–Morena Zone (SW Iberia): implications for regional extensional tectonics

Table S3: Whole-rock geochemistry for major and trace elements of Visean high-K plutonic rocks from Campo Maior and Vale de Maceiras (Portugal

Mid-Ordovician stratigraphy and volcanism in the Hølonda area, Scandinavian Caledonides: complex tectonomagmatic development following arc–continent collision near the Laurentian margin of Iapetus

Figure S4. Potassic vs. sodic HP–Nonsåsen

Visean high-K mafic-intermediate plutonic rocks of the Ossa–Morena Zone (SW Iberia): implications for regional extensional tectonics

Table S4: ID–TIMS U–Pb zircon dat

Mid-Ordovician stratigraphy and volcanism in the Hølonda area, Scandinavian Caledonides: complex tectonomagmatic development following arc–continent collision near the Laurentian margin of Iapetus

Figure S2. Adakite plots

Mid-Ordovician stratigraphy and volcanism in the Hølonda area, Scandinavian Caledonides: complex tectonomagmatic development following arc–continent collision near the Laurentian margin of Iapetus

Table S6. LA–ICP–MS detrital zircon data (Excel table)