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The Gentio metagranitoid presents equigranular and porphyritic facies, modal composition ranging from tonalite to monzogranite with calculated TZr<800 °C for most samples. Its mineralogy is dominated by quartz and feldspar (77% to 95%), biotite is the only mafic mineral present (2% to 18%) and, titanite, zircon, apatite, allanite are important accessory phases. These rocks range from metaluminous to weakly peraluminous, and have large variation in major and trace elements, and high alkali contents (>6 wt.%). Zircon analyses by LA-ICP-MS and SHRIMP yielded a concordia age of 2 119±10 Ma for the porphyritic facies and an upper intercept age of 2 111±15 Ma for the equigranular facies. The whole-rock Sm-Nd TDM ages vary from 2.4 to 2.8 Ga with εNd(2.1) values between −0.7 and −5.3, indicating crustal derivation from distinct and/or heterogeneous protoliths. Field observations indicate that the Gentio metagranitoid was formed through different pulses of magma. Individual batches were subject to little or even no fractionation process after its emplacement. Although the Gentio metagranitoid crosscuts metamafic and metaultramafic rocks akin to an oceanic arc setting, this pluton is likely originated by partial melting of a more evolved quartz-feldspathic crustal igneous rock in a post-collisional environment, after the accretion of the arcs from the Mineiro belt and rocks of the Mantiqueira Complex. [ABSTRACT FROM AUTHOR]

The recognition and evaluation of polycyclic processes in sedimentary units are critical for proper provenance analysis and sedimentary system interpretation. The chemical composition and textural maturity of detrital tourmalines and zircons allow identification of sediment source areas, transport, and deposition. This study investigates the origin and history of post-Gondwanan sediments of the Tupanciretã Formation in southern Brazil, which lacks provenance studies. The Tupanciretã Formation is in a similar setting of the Bauru Supersequence at the uppermost portion of the Paraná Basin. Detrital zircon ages indicate sediment provenance from the Transamazonian, Grenvillian, and Brasiliano orogenic cycles of the Rio Grande do Sul Shield and younger grains (280-128 Ma) record contribution from the Choiyoi and Serra Geral igneous events, with a maximum deposition age of 127 Ma. Detrital tourmaline chemical analyses points to the Sul-riograndense Shield as the ultimate source, with metapelitic, metapsamitic and granitic origins. The predominant degrees of roundness are well rounded to rounded suggest evidence of sediment recycling from sedimentary units of the Paraná Basin, with important aeolian reworking involved. Zircon U–Pb signatures are compatible with the eastern sector of the Botucatu Formation in Rio Grande do Sul as the immediate source and the northeastern Sul-riograndense Shield as the ultimate source. Intermediate sources between the Sul-riograndense Shield and the Tupanciretã Formation were Gondwanan sedimentary units of the Paraná Basin, with possible participation from the Camaquã Basin. • The grains indicate important recycling of sediments with multiple sources, With important analysis of detrital zircons. • Detrital tourmalines indicate the participation of multiple basement rocks as the ultimate source. • There was an ancient drainage percolating from SSE to NNW, carrying polycyclic sedimentary rock material. • The high degrees of grain roundness indicate polycyclic sedimentary events, with a maximum deposition age of 127 Ma. [ABSTRACT FROM AUTHOR]

The Neogene Barreiras Formation is composed of continental to shallow marine sedimentary rocks that fringe the Brazilian Atlantic coast. Due to the large outcropping extent, various open questions about the evolution of this unit are still under debate. We present new U–Pb detrital zircon age spectra of four samples from the southern Espírito Santo state (Marataízes section) and two samples from the southern Bahia state (Arraial section). In both of the studied outcrops, a basal succession composed of coarse-grained cross-bedded sandstone, conglomerate and arkose with mudstone and claystone intercalations is superposed by an upper succession composed of massive sandstone, conglomerate and wacke. The U–Pb detrital zircon age spectra of all samples are dominated by Cambrian and Neoproterozoic grains. However, while the lower portion of both sections is dominated by Ediacaran-Cambrian grains, their upper portions also present significant Cryogenian-Tonian and sparse Paleoproterozoic (mainly Rhyacian and Statherian) and Neoarchean grains. This marks an important provenance shift within the Barreiras Formation, with a simple, local provenance sourced from the G1 to G5 granite supersuites of the Brasiliano Araçuaí Orogen for the basal layers contrasting with exposure of older basement rocks and Neoproterozoic anorogenic suites during deposition of the superior layers. We interpret the lower coarse sandstone and arkose-rich succession as deposited in an alluvial setting, with mud/claystones related to local flooding plains. Tectonic movements related to the evolution of the Atlantic passive margin, as described in previous works, caused a renewed uplift of the basement areas, exposing and denuding older rocks. Then, the upper layers deposited through debris flows covering the first succession. Further geochronological data is needed to test if the erosional event responsible for exposure of older basement rocks and sourcing of the upper layers would correspond to the Tortonian Sea level fall, related to growth of the Antarctic ice sheet to its present size. In this case, deposition of the lower succession would have occurred during the early Miocene, and the upper succession during the Pliocene. Our results shed light in the complex evolution of the sedimentary rocks generally grouped under the Barreiras Formation, and suggest important tectonic and climatic shifts during the Neogene evolution of the Brazilian Atlantic coast. • Detrital zircon U–Pb analysis of two sections of the Barreiras Formation • Source areas dominated by late Neoprotezoic to Cambrian sources (G1-G5 plutons) • Archean-Paleoproterozoic basement exposed in the source areas upsection • Tectonic, climatic and sea-level changes were possible provenance shift drivers • Complex evolution of the sedimentary rocks of the Barreiras Formation [ABSTRACT FROM AUTHOR]

The genesis of Precambrian granitic batholiths related to supercontinent assembly is controversial, especially regarding their generating processes and tectonic settings. The present study focused on the Pelotas Batholith (Magmatic-arc domain) of the Dom Feliciano Belt, which comprises the southern segment of the Mantiqueira Province in southeastern South America. New U–Pb and Lu–Hf zircon data from plutonic rocks with evidence of magma mixing and mingling, as well as assimilation of wall rocks, suggest multi-stage magmatism related to flare-up episodes of intense magmatism, potentially triggered by changes in the tectonic setting. U–Pb zircon analyses yielded crystallization ages of granodioritic gneiss xenolith at 691.5 ± 7 Ma, microgranodiorite xenolith at 645.9 ± 3.7 Ma, host monzogranite at 634.4 ± 4.4 Ma, and intrusive syenogranite at 620.1 ± 4.7 Ma, all intruded by syenogranitic pegmatite at 606.9 ± 1.7 Ma. Other analyses were performed on calc-alkaline granite (633 ± 4 Ma) and peraluminous granite (609.6 ± 2.2 Ma). The Lu–Hf data highlights a model age interval ranging from 1.7 to 1.3 Ga with εNd values between −4 and 1, except for the pegmatite sample which also includes Paleoproterozoic and Archean model ages (3.3-1.6 Ga) and εNd values between −33 and −1. Furthermore, the acquired data, together with the gathered dataset Dom Feliciano Belt granites, emphasizes a contribution from slightly juvenile to crustal sources, with model ages ranging primarily from Statherian-Orosirian to Mesoproterozoic. Signature patterns are consistent with sources from African basement rocks. • The studied magma mixing outcrop represents the Granite belt's fractal evolution. • The magmatic suites are primarily classified as I-Type and S-Type granites. • The Hf isotopes present mainly Meso-to Paleoproterozoic model ages (1.7-1.3 Ga). • The εHf values are primarily slightly negative to positive. • The U–Pb dataset shows well-defined intervals of magmatic pulses. [ABSTRACT FROM AUTHOR]

[Display omitted] • New data on interbedded metavolcanic rocks inform the origin of DFB complexes. • Metamorphic complexes of the DFB Central Sector show two unrelated magmatic events. • Elemental and isotope data indicate an Andean-type magmatic arc at 800–770 Ma. • New U-Pb zircon ages reveal Passo Feio metavolcanic protoliths of 580 ± 2 Ma. • The volcano-sedimentary complexes have a common late-orogenic evolution at 580 Ma. The geochemical and isotopic signatures of magmatic events preserved in deformed metavolcano-sedimentary sequences may inform about geological setting and original basin stratigraphy. This paper discusses elemental and isotopic geochemical literature data on metavolcanic rocks interleaved with highly-deformed metasedimentary rocks from the Dom Feliciano Belt central sector, southernmost Brazil: the high-grade Várzea do Capivarita, and the lower greenschist to amphibolite facies Porongos and Passo Feio complexes. We also provide new geochemical data for seven samples and two U-Pb zircon determinations. REE patterns, together with geochronological data, permit to sort the dataset into three main groups: i) Group 1 - LaN/YbN ≈ 10, Eu/Eu* = 0.38 to 0.86; ii) Group 2 - LaN/YbN = 12 to 44, no Eu anomaly, and iii) Group 3 - negative Eu anomaly (Eu/Eu* ≈ 0.70), but higher LREEs absolute values (LaN/YbN ≈ 22), and rare basic metavolcaniclastic rocks (Bmvc). New U-Pb zircon analyses of two Passo Feio acidic metavolcanic rocks yield a crystallization age of 580 ± 2 Ma (2σ). Group 1 samples account for a magmatic event at 800–770 Ma in the Várzea do Capivarita and Porongos (Cerro da Árvore sequence) complexes. They represent a magmatic association produced from subduction-related sources, with crustal contribution shown by 87Sr/86Sr (790 Ma) > 0.715 and ƐNd (790 Ma) from −5 and −11 (up to –22). Groups 2 and 3 account for a magmatic event at ca. 600 to 580 Ma in the Passo Feio and western Porongos (Capané sequence) complexes. Groups 2 and 3 rocks are interpreted to have been sourced from subduction-related enriched mantle without major crustal contamination, with 87Sr/86Sr (580 Ma) = 0.7035–0.7050 and ƐNd (580 Ma) > -10. For the basic metavolcanoclastic sample (Bmvc), the data suggest mantle-derived origin without significant contribution of subduction-related sources, possibly indicating multiple sources for this newly-described and not yet fully understood Ediacaran magmatism. Our comparative study leads to the novel conclusion of a shared tectonic evolution between the Passo Feio Complex and the western Porongos Complex at ca. 600–580 Ma. They also corroborate a shared tectonic evolution between the Porongos Complex and Várzea do Capivarita Complex at ca. 800–770 Ma, as reported by previous authors. [ABSTRACT FROM AUTHOR]

The precursor basin of the Araçuaí – West Congo Orogenic System (AWCO) formed a large gulf within the São Francisco – Congo Paleocontinent (SFCP), where the diamictite-bearing Macaúbas Group was deposited during the Neoproterozoic. However, the lack of robust age constraints on the Cryogenian glaciogenic successions prevents correlation to one or both of the Cryogenian Snowball Earth glaciations. The present study introduces new field data and new U–Pb detrital zircon data from diamictite-bearing units on the southern margin of the São Francisco Craton, in the northeastern Araçuaí Orogen. This region is much closer to possible Ediacaran-Cryogenian igneous rocks of the southern São Francisco craton than other regions previously studied for the Macaúbas Group, enhancing the probability of detecting detrital minerals from those rocks, if they were involved as source areas. In the studied region, the Macaúbas Group is composed of metadiamictite with sparse clasts and schistified metagraywacke with bulk mineralogy similar to the quartz-muscovite-feldspar matrix of the metadiamictites. U–Pb (LA-MC-ICP-MS) dating of 182 detrital zircon grains from the Lower Chapada Acauã Formation forming the syn-glacial sequence yielded main age peaks at 939 ± 3 Ma, 1409 ± 10 Ma, 1822 ± 8 Ma, 2044 ± 7 Ma, 2551 ± 9 Ma and 3103 ± 19 Ma. The youngest concordant zircon grain found in this study aged 753 ± 12 Ma. U–Pb (LA-MC-ICP-MS) dating of 104 zircon crystals from a granitic clast recovered from the diamictite exhibits highly discordant data plotting in distinct Discordia lines with upper intercept ages of 2.0 Ga, 2.5 Ga, 2.6 Ga and 3.2 Ga, indicating derivation from the adjacent cratonic basement. The U–Pb age spectra suggests important contribution from the Archean and Paleoproterozoic basement of the São Francisco – Congo paleocontinent and metamorphic complexes, from the Mesoproterozoic intrusive and volcanic rocks of São Francisco Craton, and from the Tonian Salto da Divisa Suite. Despite the relative abundance of Cryogenian zircon grains in the surrounding prospective source areas, the studied rocks lack this interval age. The glaciogenic events in the Macaúbas basin system probably did not sample rocks with these age intervals due to the general characteristics of this type of deposit or because the sources were not exposed. Thus, the lower diamictite-bearing units of the Macaúbas Group in the northeastern São Francisco craton were deposited after ca. 753 Ma, but their correlation to either the Sturtian or Marinoan global glaciations remain speculative. • U–Pb detrital zircon data of Chapada Acauã Formation reveals a younger sedimentation age. • Top diamictite bearing unit of Macaúbas Group with Upper Tonian detrital contribution. • Data corroborates coevality of Upper Macaúbas basin system and Jequitinhonha Complex. [ABSTRACT FROM AUTHOR]

Introduction: The Rochechouart impact structure in the NW part of the French Massif Central (FMC) is characterized by deep erosion that, however, still allows the recognition of a complete suite of impact lithologies, the crater floor, and various target lithologies (e.g., [1]). We present the first results from a project that is aimed at U-Pb on zircon isotope analysis of a representative set of surface and core samples of impact melt rocks and basement lithologies. These results will help to constrain the age of the impact event and provide information about the dynamics of the impact melt formation process in terms of the protolith target rocks for the diverse impact melt rock types. The analysis of the basement samples will improve and complement the current understanding of the FMC evolution in the region of the impact structure. Methodology: Zircons from a reddish impact melt rock from Montoume, a yellow impact melt rock from Recoudert, an amphibolite from Exideuil, and a gray foliated gneiss from Moulin de Laurière have so far been analyzed for U-Pb isotope data with a Neptune Plus Thermo Finnigan LA-MC-ICP-MS coupled with a Photon-Machines 193 nm laser system at the Laboratory of Isotope Geochemistry at the University of Ouro Preto, Brazil. Results: The oldest ages registered in zircons from both basement rocks are Neoproterozoic. The youngest ages from zircons of the gneiss are Silurian (433 ± 15 Ma), and from zircons of the amphibolite we obtained Carboniferous ages (326 ± 5 Ma). The principal age peak recorded from the basement zircons is at ~362 Ma, registered in the amphibolite. Other minor basement age peaks are registered at ~327 and ~449 Ma for the amphibolite; and ~523 Ma and ~544 Ma for the gneiss. The impact melt rocks display a greater variety of ages, from the Neoproterozoic to the Triassic (203 ± 2 Ma) for the Recoudert sample, and from the Neoproterozoic to the Lower Jurassic (195 ± 3 Ma) for the Montoume impact melt rock. The most prominent age peak registered in these impactites is at ~388 Ma and is from the Montoume sample. The Permian ages are obtained principally from the Recoudert sample. Discussion: The basement ages obtained in this study can be broadly correlated with different events of the evolution of the FMC (e.g., [2] and referred therein). Pre-Ordovician ages are probably related to protolith ages of the metamorphic basement. The ~362 Ma age peak is slightly older than the Variscan collision period, and similar ages have been obtained elsewhere in the NW FMC [3]. The ~327 Ma age is probably related to the Carboniferous exhumation period. The most prominent basement age peaks are not registered in the zircons from the two impact melts. Furthermore, these impactites display age peaks that are not found for the basement rocks analyzed to date. This is probably a result of different target rock lithologies involved in the formation of both impact melt rock samples. The age peaks observed for the impact melt rocks possibly record the exhumation of high-grade rocks at ~388 Ma [4] and a Permian granitization phase [5]. Finally, ~204 Ma ages recorded in zircon from both impact melt rocks are in agreement with recent U-Pb estimations of the age of the impact event (204 ± 2.2 and 207 ± 3.6 Ma; [5]). The youngest ~194 Ma ages obtained for the Montoume sample are similar to ~195 Ma ages previously reported for Babaudus impact melt rock [5]. Further textural characterization of these zircons will help in the interpretation of this apparent post-impact age. Conclusions: U-Pb age data for zircon from an amphibolite and a gneiss from the basement of the Rochechouart impact structure show good agreement with known events in the evolution of the FMC. Impact melt rock samples from Montoume and Recoudert show a great diversity of ages, including age peaks not recorded in the basement lithologies analyzed to date, which probably relates to target rocks that still need to be analyzed. Furthermore, the age of the impact event and a younger Lower Jurassic age were obtained. [ABSTRACT FROM AUTHOR]

Sedimentary basins with epiclastic and volcanoclastic components are important geotectonic components for understanding the complex evolution of orogenic systems. The age, provenance and tectonic setting of ancient basins are, however, often hard to constrain, especially in the high-grade core of ancient mountain belts where original sedimentary and stratigraphic relations have been largely obliterated by deformation and metamorphism. In this case, analytical tools such as whole-rock geochemistry and U–Pb and Lu–Hf analyses on detrital zircon grains can be deployed to unravel the provenance and tectonic setting of high-grade metasedimentary and metavolcaniclastic units. Here, we apply these analytical tools on samples from gneissic paleosomes of migmatites found in the eastern transition zone between the Neoproterozoic–Eopaleozoic Araçuaí and Ribeira orogens (southeastern Brazil). The studied paleosomes comprise peraluminous paragneiss rich in biotite, garnet and sillimanite, metaluminous hornblende-bearing gneiss free of peraluminous silicates, and intermediate terms between these compositions, all of them with geochemical characteristics pointing to sources located in magmatic arc systems. Overall, U–Pb data from detrital zircon grains bracket a maximum sedimentation age for all samples between 600 and 627 Ma, while εHf (t) : +5.7 to −18.7 and Hf T DM model ages of 1.0–2.2 Ga suggest moderately juvenile to evolved sources for the gneiss protoliths. However, despite the similarity in age range, the analyzed samples show contrasting isotope data indicating significant variability in the source areas. Sample 7 only has grains with negative εHf (−5.9 to −18.7), most of them ranging in age from 708 Ma to 758 Ma, with very few older (1021–1143 Ma) and younger (642–651 Ma) zircons grains, indicating evolved crustal sources of distinct ages (e.g., the Late Tonian – Early Cryogenian South Bahia Alkaline Province, the Early Cryogenian magmatism found in the West Congo Belt, the Stenian to Early Tonian Espinhaço and Matadi-Noqui igneous rocks, and magmatic rocks of the early Rio Doce arc). Conversely, sample 13 has twenty grains with positive εHf values and ages between 602 and 758 Ma, suggesting sourcing from (meta)igneous rocks of the Rio Negro arc and their remelting products, and forty grains with negative εHf values with ages between 591 and 646 Ma suggesting magmatic sources in the Rio Doce arc. Additionally, the two youngest spot ages (553 Ma and 571 Ma) have highly negative εHf values (−11.1 and −16.4) suggesting their origin from collisional anatexis. Similarly, sample 12 shows detrital grains within the consistent time interval (ca. 596 Ma – 798 Ma) of the Rio Negro arc and Rio Doce arcs, reinforcing that the fragments of these arcs, or zircons that were inherited from these terranes, are potential sources to the sedimentary protoliths of the paragneisses. The regional scenario together with our field and analytical data, compared with data available in the literature, suggest the sedimentary protoliths of the studied samples filled orogenic basins related to the Rio Doce magmatic arc. Most detrital zircon ages are close to the maximum depositional age, a classical signature of orogenic basins related to magmatic arcs. The studied paragneiss unit correlates with the Nova Venécia Complex, located on the intra-arc to back-arc zones of the Araçuaí orogen, and with the orogenic succession of the distal Andrelândia Group, shared by both the Araçuaí and Ribeira orogens. Furthermore, our data also suggest the juvenile Rio Negro - Serra da Prata arc system was either amalgamated with the Rio Doce arc or that fragments of these arcs were incorporated as unmelted xenoliths and xenocrystals within the Rio Doce arc rocks before ca. 614 Ma, providing key hints to unravel the evolution of the Araçuaí - Ribeira orogenic system (AROS) and its role in the Gondwana assembly. • Paragneisses from the Araçuaí-Ribeira Orogen sourced from Ediacaran arcs. • Maximum sedimentation age for all samples between 600 and 627 Ma. • Moderately juvenile to evolved sources (εHf (t) : +5.7 to −18.7, T DM = 1.0–2.2 Ga). • Elemental geochemistry coherent with graywackes from active margin settings. • Syn-orogenic basins related to the Rio Doce (G1 Supersuite) continental-margin arc. [ABSTRACT FROM AUTHOR]

On the passive margin of southern Brazil, where the availability of sediments and coastal system conditions were adequate for forming a Ti–Zr-bearing placer in the Holocene, could there be a source of detrital contribution other than the Precambrian South American cratons? To answer that, detrital zircon U–Pb–Hf analyses were performed using the LA-ICP-MS method. The U–Pb age pattern distribution of 866 zircon grains showed that 35.3% of the grains belong to the Neoproterozoic, which covers the Brasiliano orogenic belts. However, 9.1% of the total zircons analyzed (up to 12% in some samples) correspond to grains younger than 50 Ma, restricted to the Andean orogeny in southern South America. The Hf signature of the zircons stands out by pointing to five significant and distinct groups interpreted as coming from the Andean (0–50 Ma), Gondwanides (230–380 Ma), Famatinian (380–500 Ma), Brasiliano (850–541 Ma), and Grenville (900–1300 Ma) orogens, confirming an Andean fingerprint as source rocks in addition to the sediments originating from the craton. This Andean source is related to the distal sediment contribution from the La Plata River system and Argentina rivers that discharge in the Atlantic Coast. Based on a statistical and Hf isotope approach, we defined that around 50% of the zircons grains were transported from the Argentina coast and La Plata River by the littoral drift for more than 1000 km to their final sink in the southern Brazilian coast. • A provenance study in a Ti–Zr coastal placer on southernmost Brazil • Detrital zircon U–Pb–Hf analyses were performed by the LA-ICP-MS method. • Results point to a fingerprint of an active margin in a passive margin. • La Plata and Argentine's rivers were sources of sand for south Brazil during the Quaternary. • Coastal currents were essential for the formation of these deposits. [ABSTRACT FROM AUTHOR]

• Cuxiú Formation sandstone of Aquiri region was deposited between 2705 and 2665 Ma. • Hinterland consisted of Neo- to Paleoarchaean (2705–3600 Ma) granitoids. • Hf model ages indicate reworking of late Hadean to Mesoarchean (4.0–3.0 Ga) crust. • Zircon ages and shapes suggest erosion of heterogeneous basement and short transport distance. • Correlation of zircon size vs. roundness results from fluvial transport. Provenance studies are commonly based on in situ U–Pb dating and Hf isotope analyses of detrital zircon grains, while leaving shape parameters unconsidered, even though these can provide valuable information about the hinterland and detritus transport. This is demonstrated herein by presenting a comprehensive data set derived from approximately 950 detrital zircon grains from three quartzite samples of the Cuxiú Formation of the Aquiri region, which is part of the eastern realm of the Amazon Craton. The data set combines results of zircon U–Th–Pb–Hf isotope analyses with zircon shape, and some physical parameters, including length, width, aspect ratio, roundness, typology, alpha-decay dose and density. Zircon U–Pb ages and field relationships indicate that pebbly sandstones of the Cuxiú Formation were deposited during the Neoarchaean between 2705 and 2665 Ma, likely in a fluvial or near-shoreline environment of a rift basin, with zircon grains supplied from igneous rocks of the surrounding Amazon Craton. The detrital zircon grains record crystallisation ages of 3100–2800 Ma (74%), and subordinately of 2800–2700 Ma (13%) and 3600–3100 Ma (3%). Hafnium isotope analyses further suggest crust formation in the hinterland at 4.01–3.65 Ga (14%), 3.60–3.10 Ga (85%) and 2.95 Ga (1%). Well preserved euhedral shapes of more than 50% of the detrital zircon grains, independent of U–Pb ages, suggest fast, direct supply from heterogeneous Archaean basement sources to the sedimentary basin, with a short-distance transport, plausibly in a fluvial setting. Correlation of zircon roundness with width in the size range from 50 to 150 µm indicates more intense abrasion of larger zircon grains compared to smaller ones, reflecting difference in transport mechanisms – i.e., abrasive-rolling transport vs. non-abrasive suspension transport. Similar average values for length (~120 µm), width (~66 µm), aspect ratio (1.9) and roundness (~2.5), obtained from zircon grains of very different ages (3600–2700 Ma), as well as log-normal distribution of the width parameter, suggest thorough hydrodynamic sorting during transport. Zircon typology analysis reveals a wide range of combinations of {1 0 0}:{1 1 0} prism faces with{1 0 1}:{3 0 1}:{2 1 1} pyramids, pointing to zircon crystallisation from 900 to 600 °C (average 755 °C). Uranium–Th contents indicate low α-decay doses of ≪1 × 10−15 decay events/mg for all zircon grains by the time of deposition, providing an additional explanation for the excellent zircon preservation. [ABSTRACT FROM AUTHOR]

The pre- to post-Late Neoproterozoic geological histories in the south to southwestern part of Mamfe Basin (SW Cameroon) were reported following analysis of the zircon crystals from their host rocks. A genetic model was developed for the zircon host rocks' formation conditions, and the registered post-emplacement events were presented. The obtained ages were correlated with the data available for rocks in the Cameroon Mobile Belt, SE Nigeria, and the Borborema Province of NE Brazil. Separated zircons from Araru black to whitish gneiss, Araru whitish-grey gneiss, and Mboifong migmatite were analyzed for their morphology and texture U-Th-Pb composition, and U-Pb ages. Published U-Pb zircon ages for Otu granitic pegmatite, Babi mica schist, and Nkogho I-type anatectic granite were updated. Zircon ages in Araru black to whitish gneiss; Araru whitish-grey, Mboifong migmatite, Babi mica schist, Nkogho I-type anatectic granite, and Otu granitic pegmatite date the Eburnean tectono-magmatic/metamorphic event in Cameroon and SE Nigeria. The Late Paleoproterozoic to Early Mesoproterozoic ages record extensional (continental rift) settings and anorogenic magmatism in the Borborema Province in the NE of Brazil. These ages date collisional phases between the São Francisco–Congo and West African cratons and the Saharan metacraton with metamorphism and magmatism in Cameroon. They also date the Kibarian tectono-magmatic/metamorphism and PanAfrican tectono-magmatic/metamorphism in SE Nigeria. The Late Paleoproterozoic to Early Mesoproterozoic ages date the Cariris Velhos orogeny in the Borborema Province in NE Brazil, with Early Tonian crustal rifting, magmatism, and metamorphism and the collisional phase of the Brasiliano orogeny with syn-collisional plutons and extensive shear zoning and post-collisional granite intrusions. [ABSTRACT FROM AUTHOR]