Flood basalts of the Deccan Volcanic Province erupted between about 67.5 to 60.5 Ma ago and reached a thickness of up to 3500 m. The main part consists of compound and simple lava flows with a tholeiitic composition erupted within 500,000 years at about 65 Ma. Within the compound lava flows, vesicles and cavities are frequent. They are filled by secondary minerals partly of well development and large size. This study presents data on the secondary mineralization including detailed field descriptions, optical, cathodoluminescence and SEM microscopy, X-ray diffractometry, fluid inclusions, C and O isotope analyses, and Rb-Sr and K-Ar geochronology. The investigations indicate a multistage precipitation sequence with three main stages. During stage I clay minerals and subsurface filamentous fabrics (SFFs), of probably biogenic origin, formed after the lava flows cooled down near to the Earth’s surface. In stage II, first an assemblage of calcite (I) and zeolite (I) (including mordenite, heulandite, and stilbite) as well as plagioclase was overgrown by chalcedony, and finally a second calcite (II) and zeolite (II) generation developed by burial metamorphism by subsequent lava flows. Stage III is characterized by precipitation of a third calcite (III) generation together with powellite and apophyllite from late hydrothermal fluids. Rb-Sr and K-Ar ages of apophyllite indicate a large time span for stage III. Apophyllite formed within different time intervals from the Paleogene to the early Miocene even within individual lava flows at certain localities. From the Savda/Jalgaon quarry complex, ages cluster at 44–48 Ma and 25–28 Ma, whereas those from the Nashik area are 55–58 Ma and 21–23 Ma, respectively.

A tourmaline-bearing eclogite from the Kreuzeck Mountains, Eastern Austria, is described in this study as part of an eclogite suite situated SE of the Tauern Window. These rocks formed during Eoalpine high-P metamorphism of the Austroalpine basement. They have high and variable Fe, Ti, P, Zr and Sr contents and unlike other Eoalpine eclogites their Ti–V–Zr–P–Nb–Y systematics indicates a within-plate rather than mid-ocean ridge basalt type environment for the formation of their protoliths. Major and trace element variations are consistent with progressive differentiation of a mafic magma with Fe–Ti oxide and apatite as important igneous phases and with metasomatic addition of K and Sr. The eclogites contain garnet + omphacite + quartz + epidote-group phases + calcic amphibole + K-feldspar ± phengite + rutile + apatite + zircon formed under peak metamorphic P–T conditions of ∼2·1 GPa and ∼650°C. In situ U–Pb dating of two zircons from the tourmaline-bearing sample yields concordant ages of 86 and 109 Ma. Inclusions of K-feldspar + omphacite in garnet, and the very rare presence of phengite as a matrix phase only, indicate very limited availability of fluid during the early stages of the high-P event. Tourmaline formed by fluid influx under eclogite-facies P–T conditions as evidenced by the presence of omphacite and K-feldspar inclusions, and its growth may have continued during uplift and decompression. Tourmaline shows variable and in part extremely high Sr contents of up to ∼5000 µg g⁻¹, which are amongst the highest reported so far for this phase. A possible source of B is the metapelitic country rocks that were pre-enriched in B by the intrusion of tourmaline-bearing pegmatites during a Permian metamorphic event. A crustal source of B is consistent with high Li concentrations in zircons intergrown with the tourmaline. The flow of B–Li–(K–Sr)-bearing fluids into and within the eclogites must have been very localized, as evidenced by the rare occurrence of tourmaline, significant variations in the halogen content of apatite on a thin-section scale and irregular vein-like compositional zoning on a micrometer scale in tourmaline and garnet, which is thought to mark former fluid pathways. Direct evidence for at least two types of fluid present under eclogite-facies P–T conditions is provided by texturally primary H₂O–NaCl–N₂–CH₄–CO₂ fluid inclusions in tourmaline and by H₂O–NaCl–CaCl₂ fluid inclusions in coexisting apatite and quartz. Laser ablation inductively coupled plasma mass spectrometry analysis shows that the primary fluid inclusions in quartz are rich in Ca (1·6–2·7 wt %), K (3500–4900 µg g⁻¹), B (250–370 µg g⁻¹), Sr (490–1080 µg g⁻¹) and Pb (8–16 µg g⁻¹), with total solute concentrations of up to 9·3 wt %. Indirect evidence for the presence of fluids rich in high field strength elements and large ion lithophile elements under amphibolite- and/or greenschist-facies conditions is provided by texturally late light rare earth element–Nb–Ta-rich titanite with a positive Eu-anomaly.

In the Neoarchean (~ 2.7 Ga) contact metamorphosed charnockitic footwall of the Mesoproterosoic (1.1 Ga) South Kawishiwi intrusion of the Duluth Complex, the primary metamorphic mineral assemblage and Cu–Ni–PGE sulfide mineralization is overprinted by an actinolite + chlorite + cummingtonite + prehnite + pumpellyite + quartz + calcite hydrothermal mineral assemblage along 2–3 cm thick veins. In calcite, hosted by the hydrothermal alteration zones and in a single recrystallized quartz porphyroblast, four different fluid inclusion assemblages are documented; the composition of these fluid inclusions provide p–T conditions of the fluid flow, and helps to define the origin of the fluids and evaluate their role in the remobilization and reprecipitation of the primary metamorphic sulfide assemblage.

Monometamorphic metasediments of Paleozoic or Mesozoic age constituting Schneeberg and Radenthein Complex experienced coherent deformation and metamorphism during Late Cretaceous times. Both complexes are part of the Eoalpine high-pressure wedge that formed an intracontinental suture and occur between the polymetamorphosed Ötztal–Bundschuh nappe system on top and the Texel–Millstatt Complex below. During Eoalpine orogeny Schneeberg and Radenthein Complexes were south-dipping and they experienced a common tectonometamorphic history from ca. 115 Ma onwards until unroofing of the Tauern Window in Miocene times. This evolution is subdivided into four distinct tectonometamorphic phases. Deformation stage D1 is characterized by WNW-directed shearing at high temperature conditions (550–600°C) and related to the initial exhumation of the high-pressure wedge. D2 and D3 are largely coaxial and evolved during high- to medium-temperature conditions (ca. 450 to ≥550°C). These stages are related to advanced exhumation and associated with large-scale folding of the high-pressure wedge including the Ötztal-Bundschuh nappe system above and the Texel–Millstatt Complex below. For the area west of the Tauern Window, F2/F3 fold interference results in the formation of large-scale sheath-folds in the frontal part of the nappe stack (formerly called “Schlingentektonik” by previous authors). Earlier thrusts were reactivated during Late Cretaceous normal faulting at the base of the Ötztal–Bundschuh nappe system and its cover. Deformation stage D4 is of Oligo-Miocene age and accounted for tilting of individual basement blocks along large-scale strike-slip shear zones. This tilting phase resulted from indentation of the Southern Alps accompanied by the formation of the Tauern Window.