The Cuesta Ridge ophiolite is a well-preserved remnant of the Middle Jurassic Coast Range ophiolite tectonically overlying rocks of the Franciscan complex. It is a nearly complete ophiolite section, consisting of over 1 km of serpentinized harz-burgite and dunite, sills of wehrlite, pyroxenite, and lherzolite, isotropic gabbro, a sheeted complex of quartz-hornblende diorite, an ∼1200-m-thick volcanic section, late-stage mafic dikes, and 5–10 m of tuffaceous radiolarian chert. The volcanic section at Cuesta Ridge has two chemically distinct volcanic groups. The lower volcanic section is characterized by low Ti/V ratios (11–21), enriched large ion lithophile element (LILE) concentrations, and depleted high field strength elements (HFSEs). Boninitic lavas with high MgO, Cr, and Ni abundances are present in this suite, along with arc tholeiites (basaltic andesites to dacites). Basalts of the upper volcanic section, which conformably overlie the lower volcanic section, and late-stage basaltic dikes that crosscut the hornblende–quartz diorite plutonic section are characterized by higher Ti/V ratios (20–27) and HFSE abundances and lower LILE abundances than the underlying section. These late-stage volcanic rocks have mid-ocean-ridge basalt–like chemistry. The field and geochemical data indicate formation in a suprasubduction-zone setting above an east-dipping proto-Franciscan subduction zone due to the onset of subduction and subsequent slab rollback. Multiple stages of magmatism ensued, until the emplacement of the late-stage dikes and uppermost flows. These late-stage dikes, which are present in several Coast Range ophiolite remnants, signify the end of ophio-lite formation and are interpreted to represent a Late Jurassic ridge collision.

Late Cenozoic volcanic rocks on the island of Sardinia are mildly alkaline-transitional lavas, dominantly hawaiites, mugearites, and transitional basalts with minor phonolites and trachytes, which form ∼80% of the entire sample population. Tholeiitic basaltic andesites form the remaining 20% of the analyzed rocks. The oldest lavas, the ca. 6.6–4.4 Ma radiogenic Pb volcanic group, are in southern Sardinia; they have geochemical characteristics very similar to most Circum-Mediterranean Anorogenic Cenozoic Igneous Province rocks. After a gap of ∼0.5 m.y., volcanism occurred in central and northern Sardinia, from ca. 3.9 to ca. 0.1 Ma. These products, the unradiogenic Pb volcanic group, are geochemically very different. Their geochemical characteristics (relatively high SiO 2 , low CaO, and CaO/Al 2 O 3 , relatively high Ni, relatively low high field strength elements, low heavy rare earth elements, high Ba/Nb and La/Nb, slightly high 87 Sr/ 86 Sr, and unradiogenic 143 Nd/ 144 Nd and 206 Pb/ 204 Pb ratios) are considered to be derived from an orthopyroxene-rich lithospheric mantle source. The origin of this enrichment in orthopyroxene is a consequence of SiO 2 -rich melt derived from delaminated and detached ancient lower continental crust reacting with mantle peridotite. The presence of two distinct groups of rocks (unradiogenic Pb volcanics and radiogenic Pb volcanics) in a very close geographic position is related to the existence of a lithospheric discontinuity running roughly E-W in southern Sardinia.

A vertical section of Upper Paleozoic sandstones from southern Transdanubia (Mecsek-Villány area, Tisza mega-unit, Hungary) has been analyzed for major and trace elements, including rare earth elements (REEs). In addition, the clay mineralogy of the sandstone samples and the petrography and geochemistry of gneiss and granitoid clasts extracted from the associated conglomerates have been determined. Geochemistry of the sandstone samples analyzed in this study shows that these rocks were predominantly derived from a felsic continental source; nevertheless, compositions vary systematically up-section. The Pennsylvanian (Upper Carboniferous) Téseny Formation has higher SiO 2 and lower Na 2 O, CaO, Sr, high field strength element (HFSE), and ΣREE contents relative to the Permian strata. Its high K 2 O and Rb contents together with the presence of abundant illite-sericite suggest a potassium metasomatism in this formation. Clay mineralogy and large ion lithophile element (LILE) contents of the Lower Permian Korpád Formation vary spatially and are interpreted as local variations in composition of the source region and postdepositional conditions. Zr and Hf abundances and REE patterns, however, show that this formation was derived from mature upper continental crust. The Upper Permian Cserdi Formation has higher TiO 2 , Th, U, Y, Cr, and heavy (H) REE contents, and higher Cr/Th and Cr/Zr ratios relative to the underlying formations. These trends can be explained by a sedimentary system dominated by highly weathered detritus derived from combined recycled-orogen, basement-uplift, and volcanic-arc provenance in the Téseny Formation, with an increased proportion of less weathered detritus derived from combined volcanic and basement-uplift provenances in the Permian formations. Characteristics of the Cserdi unit may reflect relatively proximal derivation from a felsic volcanic source.

The evolving chemistry of the Chachahuén volcanic complex provides evidence for transient entry of a subduction zone component into the mantle wedge over a late Miocene shallow subduction zone under the Neuquén Basin. The Chachahuén complex, which is in the backarc of the Andean Southern Volcanic Zone near 37°S and some 500 km east of the Chile Trench, occurs at the intersection of NE and SE fault systems that parallel regional trends. Support for a shallow subduction-zone setting at the time of eruption and during the contractional uplift of the Sierra de Chachahuén comes from K/Ar and new 40 Ar/ 39 Ar ages, mineral assemblages, major and trace element chemistry, and Nd-Sr-Pb isotopic compositions. Importantly, the chemistry of the Chachahuén rocks requires an arc-like component in the mantle that is absent in both early Miocene or Pliocene alkaline lavas erupted in the same region. The oldest Chachahuén volcanic rocks are the ca. 7.3–6.8 Ma Vizcachas group orthopyroxene-bearing andesites to rhyodacites that erupted from fissures and small centers along the NE-trending fault system. Intraplate chemical tendencies in the most silicic samples are attributed to mantle-derived basalts interacting with a lower crust that has a chemical imprint that reflects older alkaline magmatic events. Younger Chachahuén group volcanic rocks erupted at ca. 6.8–6.4 Ma from vents generally aligned along the NE-trending fault system and ca. 6.3–4.9 Ma magmas that erupted from a trap-door–type caldera and flanking stratovolcanoes along the NW-trending fault system. These high-K basaltic to dacitic rocks contain amphibole phenocrysts and show arc-like high field strength element depletions that are the strongest in basaltic andesite lavas. Parallels between Chachahuén volcanic rocks and uplift of the Sierra de Chachahuén with late Miocene Pocho volcanic rocks and uplift of the Pampean Ranges over the modern Chilean flat-slab support transient Miocene shallow subduction zone under the Neuquén Basin.

The Late Cretaceous calc-alkaline to alkaline plutons in the Central Anatolian crystalline complex are intrusive into metamorphic and ophiolitic rocks and mark a major magmatic pulse in the late Mesozoic evolution of the eastern Mediterranean region. We grouped the plutonic rocks with similar mineral and chemical compositions and inferred genetic relations into the granite, monzonite, and syenite supersuites. Granitic plutons mainly occur along the western edge of the Central Anatolian crystalline complex, whereas syenitic plutons form smaller bodies that crop out in the inner part. The granite supersuite is composed of granitic to granodioritic rocks, and the monzonite supersuite consists mainly of quartz monzonite and monzonitic rocks; both supersuites show enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE). The granitic-granodioritic rocks have compositions typical of high-K calc-alkaline and high-K shoshonitic series, whereas the monzonitic rocks display compositions characteristic of shoshonitic series. The syenite supersuite consists of quartz syenite, syenite, and nepheline- and pseudoleucite-bearing alkali rocks and shows more enrichment in LILE and a slight enrichment in HFSE compared to the other two supersuites. All three supersuite rocks have high 87 Sr/ 86 Sr and low 143 Nd/ 144 Nd ratios. These geochemical features suggest that the granite and monzonite supersuite magmas were derived from a subduction-modified and metasomatized mantle source and that the syenite supersuite magmas were derived from an enriched mantle source with considerable crustal contribution. New 40 Ar/ 39 Ar ages at 77.7 ± 0.3 Ma for the granite, 70.0 ± 1.0 Ma for the monzonite, and 69.8 ± 0.3 Ma for the syenite supersuite rocks indicate progressive evolution of the Central Anatolian crystalline complex magmatism from calc-alkaline to alkaline compositions with time. The latest Cretaceous emplacement of the complex's plutons and the chemical evolution of their magmas were syn-collisional in nature, after the leading edge of the Tauride platform collided with a trench in the Inner Tauride ocean and became partially subducted. Subsequent slab break-off resulted in asthenospheric upwelling and perturbation of the subduction-metasomatized lithospheric mantle that collectively produced the primary melts for the Central Anatolian crystalline complex plutons. These melts evolved through combined assimilation–fractional crystallization and mixing-mingling processes during their ascent and were affected by the interactions between mantle-derived and crustal-derived magmas. The late phases of this intracontinental magmatism were accompanied by tectonic extension of the thermally weakened orogenic crust in the Central Anatolian crystalline complex.