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The Oaxacan Complex Carboniferous-Permian sedimentary cover in southern México records provenance shifts through time, reflecting the collision between Gondwana and Laurentia to amalgamate Pangea. The integration of petrological analysis and LA-ICP-MS U-Pb zircon geochronology from Santiago, Ixtaltepec and Yododeñe formations compared with adjacent terranes suggests that: (1) during the Early Mississippian, the Santiago Formation received sediments mainly from local sources such as the Oaxacan Complex and Tiñu Formation, with minor contributions from adjacent peri-Gondwana sources. The magmatic activity may have started during this time (~359–346 Ma) (2) during the Late Mississippian (Ixtaltepec Formation), detrital zircon grains of Ediacaran-Cambrian age are dominant, derived from sediments either related to the Pan-African/Brasiliano orogeny or the opening of the Iapetus Ocean; (3) during the Late Mississippian-Middle Pennsylvanian, intercalated marine volcaniclastic sandstone (Ixtaltepec Formation) provides the first record of Carboniferous arc-related volcanism reported in southern Mexico, dated between 330 and 308 Ma; (4) the early Permian Yododeñe Formation records the exhumation and erosion of the sedimentary cover during the final stage of Pangea assembly. Rhyodacitic subvolcanic sills and lavas dated at ~282–270 Ma are present throughout the succession. Volcanism and ca. 360–308 Ma detrital zircon grains could be associated with a Carboniferous magmatic arc formed by subduction of the Rheic oceanic plate beneath Gondwana. Slightly younger detrital zircon and subvolcanic rocks dated at ~300–270 Ma are linked to a western Pangea arc developed in response to the subduction of the Paleo-Pacific Ocean following Pangea assembly. Our results suggest that the Carboniferous-Permian units were deposited in a peri-arc basin, sharing sediment provenance with the Maya and Coahuila blocks, the Sierra de Juárez Complex, and northwestern South America. [ABSTRACT FROM AUTHOR]

The provenance of Triassic Vieux Emosson Formation, autochthonous sediments of the Aiguilles Rouges massif (External Alps), was determined from U–Pb ages of detrital zircons. In addition, two samples of Late Carboniferous sandstones from the Salvan‐Dorénaz basin were included to extend the database of potential source rocks. Overall, age data from the four samples are largely comparable, each with a wide range of ages, indicating similar source rocks. The compositionally and texturally immature strata of the Vieux Emosson Formation suggest a local sediment source. However, not all detrital zircons can be accounted for by the ages of the local polymetamorphic pre-Mesozoic basement, which consists mainly of paragneiss, Ordovician orthogneiss and Late Carboniferous, Variscan-related, magmatic and sedimentary rocks. Ordovician zircons were common in the samples, but Late Carboniferous zircons were only abundant in one sample. Early Cambrian and older zircons were likely recycled from the paragneiss. Recycled zircons primarily represent Cadomian orogenic events (~ 550–650 Ma); older zircons are from eastern Gondwana and West African craton sources. Abundant late Cambrian (~ 500 Ma) and Silurian (~ 425 Ma) zircons likely represent Cadomian rifting and the magmatic events that produced the Ordovician orthogneiss, respectively. Permian zircons were only found in one Triassic sample, and are possibly related to magmatic activity associated with post-Variscan extension. The age data of the detrital zircons in the Triassic Vieux Emosson Formation and in the sandstones from the Late Carboniferous Salvan-Dorénaz basin indirectly dates the source rocks and for the first time confirms Cadomian basement in the Aiguilles Rouges massif. Source rocks for the Silurian, Permian, and to a lesser degree, late Cambrian zircons are not documented in the local basement, and either have been eroded away or are now located to the southeast beneath Penninic nappes. [ABSTRACT FROM AUTHOR]

We applied SHRIMP zircon U-Pb age dating to ultrahigh-temperature (UHT) sapphirine-bearing orthopyroxene garnet (SOG) granulite and biotite-hornblende (Bt-Hbl) gneiss in the Schirmacher Hills, East Antarctica. In the Bt-Hbl gneiss, concordant ages of 657 ± 7.1 and 807 ± 9.1 Ma were obtained from zircon overgrowth rims and zircon cores, with oscillatory and irregular zoning, respectively. The zircon overgrowth rims (657 ± 7.1 Ma) with low Th/U ratios from the Bt-Hbl gneiss are interpreted as having a metamorphic origin. Oscillatory-zoned and/or irregularly zoned zircon cores may have crystallized during an igneous event at 807 ± 9.1 Ma; 800-Ma igneous events have not previously been recognized in central Dronning Maud Land (DML) inland nunatak. Zircons in the SOG granulite yielded a concordant age of 643 ± 6.5 Ma, using analyses of sector-zoned and simple-zoned grains. These zircons have relatively high Th/U ratios with a narrow range, and they occur in association with garnet breaking down to form cordierite. The 643 ± 6.5-Ma age obtained from these zircons is interpreted as the timing of crystallization from a high-Th/U partial melt soon after peak metamorphism. The combination of a ca. 800-Ma igneous age and 660-640-Ma metamorphic ages obtained from Schirmacher Hills is different from that of other neighboring parts of central DML. In addition, a metamorphic PT path involving ultrahigh temperatures at early and subsequent isobaric cooling (IBC) stages at around 650 Ma has not previously been known in the central DML nunatak region. The Ca. 650-Ma UHT metamorphic event probably occurred in a back-arc tectonic setting and predates the main collisional event of central DML (ca. 550-500 Ma). [ABSTRACT FROM AUTHOR]

Abstract: Zircon and monazite U–Pb data document the geochronology of the felsic crust in the Mozambique Belt in NE Mozambique. Immediately E of Lake Niassa and NW of the Karoo-aged Maniamba Graben, the Ponta Messuli Complex preserves Paleoproterozoic gneisses with granulite-facies metamorphism dated at 1950±15Ma, and intruded by granite at 1056±11Ma. This complex has only weak evidence for a Pan-African metamorphism. Between the Maniamba Graben and the WSW–ENE-trending Lurio (shear) Belt, the Unango and Marrupa Complexes consist mainly of felsic orthogneisses dated between 1062±13 and 946±11Ma, and interlayered with minor paragneisses. In these complexes, an amphibolite- to granulite-facies metamorphism is dated at 953±8Ma and a nepheline syenite pluton is dated at 799±8Ma. Pan-African deformation and high-grade metamorphism are more intense and penetrative southwards, towards the Lurio Belt. Amphibolite-facies metamorphism is dated at 555±11Ma in the Marrupa Complex and amphibolite- to granulite-facies metamorphism between 569±9 and 527±8Ma in the Unango Complex. Post-collisional felsic plutonism, dated between 549±13 and 486±27Ma, is uncommon in the Marrupa Complex but common in the Unango Complex. To the south of the Lurio Belt, the Nampula Complex consists of felsic orthogneisses which gave ages ranging from 1123±9 to 1042±9Ma, interlayered with paragneisses. The Nampula Complex underwent amphibolite-facies metamorphism in the period between 543±23 to 493±8Ma, and was intruded by voluminous post-collisional granitoid plutons between 511±12 and 508±3Ma. In a larger context, the Ponta Messuli Complex is regarded as part of the Palaeoproterozoic, Usagaran, Congo-Tanzania Craton foreland of the Pan-African orogen. The Unango, Marrupa and Nampula Complexes were probably formed in an active margin setting during the Mesoproterozoic. The Unango and Marrupa Complexes were assembled on the margin of the Congo-Tanzania Craton during the Irumidian orogeny (ca. 1020–950Ma), together with terranes in the Southern Irumide Belt. The distinctly older Nampula Complex was more probably linked to the Maud Belt of Antarctica, and peripheral to the Kalahari Craton during the Neoproterozoic. During the Pan-African orogeny, the Marrupa Complex was overlain by NW-directed nappes of the Cabo Delgado Nappe Complex before peak metamorphism at ca. 555Ma. The nappes include evidence for early Pan-African orogenic events older than 610Ma, typical for the Eastern Granulites in Tanzania. Crustal thickening at 555±11Ma is coeval with high-pressure granulite-facies metamorphism along the Lurio Belt at 557±16Ma. Crustal thickening in NE Mozambique is part of the main Pan-African, Kuunga, orogeny peaking between 570 and 530Ma, during which the Congo-Tanzania, Kalahari, East Antarctica and India Cratons welded to form Gondwana. Voluminous post-collisional magmatism and metamorphism younger than 530Ma in the Lurio Belt and the Nampula Complex are taken as evidence of gravitational collapse of the extensive orogenic domain south of the Lurio Belt after ca. 530Ma. The Lurio Belt may represent a Pan-African suture zone between the Kalahari and Congo-Tanzania Craton. [Copyright &y& Elsevier]

U–Pb SHRIMP detrital zircon dating of ten samples of metamorphic "basement" rocks in north-central Chile and one granitic rock, improve knowledge of sedimentary, metamorphic and plutonic events in this segment of the Andean margin. The oldest possible sedimentation ages (Ordovician) come from a micaschist at Huentelauquén (477 Ma) and a granofels from a migmatite at Las Cruces (470 Ma) whose garnet-bearing granitic neosome (ca. 320 Ma) is essentially coetaneous with the extensive Coast Range Batholith. The rest of the samples show probable Carboniferous or Late Triassic maximum depositional ages. The late Paleozoic low-to-medium grade metasedimentary components of the basement, interpreted as forming part of a paleo-accretionary complex, have detrital zircon age patterns with prominent Famatinian and Grenville-age peaks; these are much less prominent in the Late Triassic rocks. The latter were deformed and metamorphosed shortly after their deposition, although some do not show visible evidence of metamorphism. Contemporaneous Triassic sedimentary, metamorphic and igneous events are recorded in Mejillones Peninsula (22°S) and in the Chonos archipelago (44°–47°S) but not in the 34°–42°S central Chile sector of the fossil accretionary complex. These events predate generalized Jurassic subduction beneath the western Gondwana continental margin that initiated the Andean orogenic cycle. • New SHRIMP U-Pb zircon dating of the sedimentary, metamorphic and plutonic events in north-central Chile segment of the Andean margin. • Central Chile basement is mostly Carboniferous to late Triassic, with the Carboniferous sedimentary protoliths having Proterozoic to early Paleozoic provenance. • Triassic protoliths record pre-Jurassic subduction and metamorphism. • Triassic metamorphism is well established in the Norte Chico segment, but absent in the south-Central Chile segment. • Reinforcing the N-S segmented nature of the accretionary margin to southwestern Gondwana. [ABSTRACT FROM AUTHOR]