The basement of the sierras of Fiambala and Altohuasi, in the Puna-Sierras Pampeanas transition (NW Argentina), consists mainly of early Cambrian metamorphic rocks (Fiambala Metasedimentary Complex; new name) and granitoids (Loconte Intrusive Complex; new name). The metasedimentary complex consists of: 1) the Taton Unit (gneisses, metatexites, diatexites and mylonites); and 2) the Laguna Helada Unit (low-to medium-grade fine-grained metaconglomerates with subordinated metapsammites, slates, phyllites, schists, mylonites and marbles). U-Pb zircon geochronology performed in the two units yields similar results suggesting that they were sourced from the same basements and probably belong to a continuous stratigraphic pile prior to metamorphism and ductile shearing. These units show a main group of ages between ca. 0.95 and 1.10 Ga, and a secondary group at ca. 1.15-1.25 Ga, with a minor peak at ca. 1.33 Ga, and few Paleoproterozoic-Neoarchean ages. This, along with zircon metamorphic overgrowths of 526 +/- 4 Ma found in the Taton Unit, and regional correlations, indicate that sedimentation took place in Ediacaran to early Cambrian times, in a mixed carbonatesiliciclastic platform bordering the extinct Clymene Ocean. Comparisons (lithology, Sr-isotopes and detrital zircon data) with similar successions recognized elsewhere in the Sierras Pampeanas, southern Puna, Cordillera Frontal, and Cordillera Oriental suggest that the sediments came from the same source areas and that they were part of a common sedimentary environment, i.e., the Difunta Correa Basin. The main source areas were the Grenville and the Granite-Rhyolite provinces of Laurentia and the MARA block. This basin-now dismembered by Paleozoic deformation-is one of the many basins formed along the margins of the Clymene Ocean lying in NW Argentina, southern Brazil, Paraguay, and Rio de la Plata craton. The closure of this ocean, during the early Cambrian Pampean orogeny resulted in the low-to high-grade metamorphism of the Fiambala Metasedimentary Complex.

A robust U-Pb zircon dataset previously published in this journal revealed a magmatic system with protracted activity, characterized by three major crystallization events at 391 +/- 1, 384 +/- 1, and 379 +/- 2 Ma. Based on these data, we proposed a conceptual model that suggests the existence of a deep mush reservoir, which enabled prolonged zircon antecrysts crystallization (ca. 395-384 Ma), followed by the crystallization of younger zircon (i.e. authocryst, 379 Ma) during emplacement. New Lu-Hf zircon data from the same U-Pb dated domains reveal that the parental magma was derived from a single heterogeneous source involving both subcontinental lithospheric mantle and Early Palaeozoic lower continental crust. Notably, Lu-Hf data from zircon indicate significant compositional variability in the magma, with a wide epsilon Hft ranges during the zircon crystallization events. This marked compositional diversity in epsilon Hft values are attributed to the crystallization of zircon antecrysts from isotopically distinct microdomains that formed melt pockets within the mush reservoir, accounting for the complex Hf isotopic signatures observed in magmatic zircon populations. These conditions persisted during magma ascent and shallow emplacement, where zircon autocrysts grew. Zircons that previously crystallized from compositionally distinct microdomains were juxtaposed within a single rock volume at the hand specimen scale, resulting in the presence of zircon crystals with different U - Pb ages but similar epsilon Hft values, or crystals with the same U - Pb ages but contrasting epsilon Hft values, all within the same rock sample. epsilon Hft zircon data, combined with geochronological and whole-rock chemistry evidence, support a model in which differentiation occurred mainly within the mush reservoir, with subsequent ascent and emplacement involving magmas with diverse geochemical compositions. Our findings indicate that whole-rock isotopic systems (e.g. Sm-Nd, Rb-Sr) reflect only the final integrated signal of the magmatic system, masking internal heterogeneity.

The origin and evolution of the Rio Grande Rise is deeply related to the opening of the South Atlantic Ocean. The geology of the plateau records the transition from divergent plate margins at the Mid-Atlantic Ridge to an intraplate tectonic setting. Despite the potential to bring insights into the complex tectono-magmatic processes involved in the development of the Rio Grande Rise, there is an overall lack of integrated petrological studies regarding its intraplate Eocene alkaline magmatism. We have investigated trachytes, trachyandesites, alkali basalts, a trachybasalt and a basanite dredged from the western Rio Grande Rise to characterize its magmatic system. Integrated petrography, mineral chemistry and whole-rock geochemistry suggests that these rocks have evolved in a complex transcrustal polybaric magmatic system, where crystals were remobilized by host liquids with different composition at distinct depths. Disequilibrium between crystals and host magmas is evidenced by abundant clinopyroxene macrocrysts with resorbed or corroded cores and rims with contrasting composition, as well as by resorbed feldspar macrocrysts. Clinopyroxene crystals also record cyclic compositional variations in magmatic chambers submitted to multiple magma recharge episodes and a strong control by fractional crystallization. U-Pb dating of zircons from a trachyte yielded an age of 46.9 ± 0.3 Ma, which reinforces the importance of the Eocene volcanism from the western Rio Grande Rise. Moreover, results from Pb, Sr and Nd isotope analysis reveal that Eocene alkaline volcanic rocks from the Western Rio Grande Rise have EMI-flavored Tristan-type signatures. This suggests that the mantle sources from the western Rio Grande Rise and from the Walvis Ridge and Guyot Province magmatism still shared common characteristics long after its separation from the Walvis Ridge.

The evolutionary onset of animal biomineralization in the late Ediacaran (ca 555–538 Ma) is marked by the global appearance of enigmatic tubular fossils with unresolved phylogenetic relationships. Among these, Corumbella werneri from the Tamengo Formation (Corumbá Group, Brazil) has been variously interpreted as affiliated with cnidarians or bilaterians. Using synchrotron imaging and machine learning, we analysed new specimens of C. werneri to reconstruct their original skeletal organization. Our findings reveal that Corumbella’s tubes were originally conico-cylindrical. Large individuals of Corumbella, including less compacted specimens, and compression experiments with modern annelid tubes all indicate that previous reconstructions of a quadrate outline and midline features were misled by taphonomic artefacts. We also show that the wall of Corumbella is composed of a single layer of ring-shaped elements. Unlike the fourfold symmetry of scyphozoans or the complex cataphract-like structures of Cambrian bilaterians (e.g. halkieriids, tommotiids and wiwaxiids), Corumbella displays structural similarities with other late Ediacaran corumbellomorphs, such as Costatubus. These taxa exhibit a distinctive barrel-on-barrel tube construction, with modular elements stacked on each other rather than nested. Our findings redefine Corumbella’s morphology and phylogenetic affinities, contributing to a broader understanding of early biomineralizing metazoans and their ecological roles in the Ediacaran biosphere.

The Southern Granulite Terrane (Dharwar Craton), South India, is a key unit for understanding the origin of charnockite. New U-Pb and Lu-Hf analyses in zircon crystals from 16 samples representing a wide variety of litho-types from the quarries in Kabbaldurga reveal a complex geological history in the Archean and early Paleoproterozoic. Magmatic protoliths predominantly record Paleoarchean ages between 3.4 and 3.2 Ga. Combined U-Pb and Lu-Hf signatures indicate a history of recurrent crustal anatexis, juvenile magmatic input, and felsic injections. Mesoarchaean magmatic charnockites were generated mainly from hornblende-dehydration melting ofPaleoar-chaean mafic rocks. In addition, Peninsular Gneissic Complex of the Dharwar Craton, commonly described as TTG suites, are likely generated by melting of hydrated basalt. The new data are consistent with the idea of a convecting magmatic cycle and also support the proposal that the southern Dharwar Craton comprises a tilted cross-section through the Archaean crust. Paleoproterozoic high-temperature event is documented here as a complex unit involving juvenile mafic magmatism, granulite facies imprints and crustal anatexis as well as felsic injections, occurring within a short time period around 2.5 Ga.

This study presents the first detrital zircon U-Pb analysis alongside new petrographic data from the Jejenes Formation (Serpukhovian-Bashkirian), located on the southern margin of the Paganzo Basin, Argentina in Southwest Gondwana. The results were compared with previously published data from other synchronously deposited units to the north (Guandacol Formation) and northeast (Malanzan Formation). Notably, glacigenic deposits are present in both the Guandacol and Jejenes formations but absent in the Malanzan Formation. A sedimentary provenance analysis was conducted for the three units, highlighting similarities and differences among the depocenters, allowing for the reconstruction of the paleogeographic and topographic landscape of the Paganzo Basin during the Serpukhovian-Bashkirian time. The comparative analysis supports the idea of disconnection and isolation among the three depocenters with each unit recording predominantly proximal sources and the recycling of pre-Carboniferous substrate. Although certain similarities exist in the age distribution of the detrital zircon grains recorded for the Malanzan and Guandacol formations, this does not imply that the depocenters were connected or fed by the same source area. Instead, these successions were likely sourced from rocks with a similar geological history, resulting in comparable age distributions due to sediment recycling. Thus, the results support a conservative approach when estimating sedimentary provenance in ancient glacigenic deposits, emphasizing the need to evaluate local sediment sources. The absence of glacigenic deposits in the Malanzan Formation could be linked to a lower topography, linked to distinct tectonic histories in the Pie de Palo, Valle Fertil, and Chepes-Malanzan ranges, underscoring the role of tectonic inheritance in the distribution of glacial centers during the Late Paleozoic Ice Age.

This work delves into the intricate Paleoproterozoic geological setting of Uruguay, focusing on the Rio de la Plata Craton (RPC) and its prominent constituent Piedra Alta Terrane (PAT). The PAT constitutes the core of the RPC, characterized as a complex geological entity that encompasses a granite-migmatite basement, metamorphic belts, granite intrusions, and Proterozoic magmatism. To the west, it interfaces with the Transbrasiliano-Kandi tectonic corridor, bounded by the Late-Neoproterozoic Pampia Terrane. The PAT s southeastern boundary extends to Sierra de Tandil and perhaps to Sierra de La Ventana, demarcating its limits with Phanerozoic rocks of the North Patagonian Massif. The Sarandi del Yi shear zone defines the eastern limit of the PAT. Despite varied interpretations of the Piedra Alta Terrane's significance, it is important to note that consensus prevails regarding its four major associations: a granite-gneiss-migmatitic basement complex, three volcanosedimentary belts of low to medium metamorphic grade, diverse late igneous intrusions, and extensional Statherian magmatism (1.79 Ga), represented by tholeiitic gabbroic dikes. In this study, a novel tectonic model for the PAT evolution emerges, supported by an extensive zircon dataset comprising new U-Pb ages, Hf isotopes, and trace element geochemistry. The analytical core involves U-Pb analyses on zircon for dating igneous rocks and establishing the provenance and maximum age of deposition of metavolcanosedimentary sequences. Lu-Hf isotopic analyses on the same zircon crystals provide petrogenetic insights, revealing episodes of crustal growth and minor recycling. Trace element geochemistry and zircon epsilon Hf(t) data further accentuate these findings, hinting at mantle source enrichment due to subduction within an intraoceanic magmatic-arc arc setting.

The first basement outcrops west of the Rio de La Plata craton are metabasaltic and metasedimentary units of the Sierra Chica belt, part of the Eastern Sierras Pampeanas. These are orthoamphibolites and subordinate garnetbiotite gneisses and metacarbonate sequences that are intruded by Cambrian calc-alkaline and peraluminous rocks of the Pampean Orogeny. In accordance with one of the leading tectonic models for the region, new provenance data from this research suggest that the metabasaltic-metasedimentary association represents the proximal deposits of a Late Neoproterozoic island -arc. This contribution brings new geochemical and geochronological evidence from orthoamphibolites located on different sites along the Sierra Chica belt, which are interbedded with metacarbonate and gneisses outcrops, showing tholeiitic compositions, island -arc related tectonic settings, and Cryogenian to Ediacaran crystallization ages. Moreover, silicate -rich metacarbonates interbedded within the same sequences yielded a maximum depositional age of 569 Ma, reinforcing the assumed age for the sequence. All things considered, these rocks are interpreted as old basic lava flows and gabbro dikes linked to an island -arc activity, interspersed within the carbonatic and siliciclastic shelf sediments, together constituting the Neoproterozoic C ordoba Arc from the Sierra Chica belt. A depositional analogy with the presentday Caribbean island -arcs deposits suggests that these sequences could have been part of Oceanic Arc Depositional Systems (OADS) during the diachronous closure of the Goi as ocean and the final assembly of West Gondwana. Overlapping thermo-tectonic processes associated with the Pampean Orogeny are ubiquitous throughout all the studied outcrops, as evidenced by the petrography, the zircon morphology, and the U-Pb results, indicating a complex scenario towards a Late Cambrian slab break -off event.

A provenance study through petrography, whole-rock geochemistry, and zircon U-Pb-Th and Lu-Hf systematics suggests that the lowermost strata of the Parana Basin (460-380 Ma) record a recycled orogen provenance with mixing trend between mature polycyclic quartzose detritus and mafic/intermediate contributions. Sources with felsic compositions are indicated by the Lower Parana Group, as it is suggested by the relative enrichment of Zr/ Y, Th/Sc, and Y/Sr ratios. Meanwhile, the Iapo Formation received additional contributions from Archean mafic/ intermediate plagioclase-rich sources (Eu* = 0.81). The Tonian juvenile (900-800 Ma) detrital zircon population from the Pre-Carboniferous strata with eHf(t) ranging from +3 to +11, in additional, late-Tonian population with an important crustal component (eHf(t) ranging from 12 to 8), provide evidence that the Ribeira Fold Belt constitutes the primary sedimentary source for the lowermost strata. Juvenile early-Tonian (950-900 Ma) and middle-Tonian (810-750 Ma) detrital zircon population suggests an additional provenance derived from the Sao Gabriel Domain, located at the southern border of the basin. Late-Ediacaran to early-Cambrian detrital zircon population suggest sources from the Eastern Pampean Range whereas a restricted detrital zircon population younger than 500 Ma with eHf(t) signatures ranging from 3 to 32, is consistent with a provenance from the Famatinian magmatic arc and associated rocks. In contrast to the detrital zircon population from the Pre-Carboniferous strata, the Itarare Group (similar to 310 to 298 Ma) reveals juvenile Ordovician sources (eHf(t) ranging from 2 to +2) and a restricted population encompassing both evolved and juvenile sources with a "Grenvillian" signature.

We propose a conceptual model for the magmatic system that gave rise to the Devonian and Carboniferous subduction-related magmatism in the Frontal Cordillera of Argentina, (representing the pre-Andean margin of SW Gondwana), integrating previous geochronological studies with new geochronological data from granitoids and subvolcanic dikes, which include reported petrological, geochemical, and isotopic data. This conceptual magmatic system postulates an extended magmatic activity, similar to that reported in a previous study for the Devonian foreland magmatism located in the present-day Sierras Pampeanas of Argentina. The geochronological data play a central role in the model, and lead us to postulate the presence of a deep mush reservoir, where a prolonged magmatic activity, permitted the extended crystallization of Devonian (ca. 400 +/- 3 and 414 +/- 3 Ma) and Carboniferous antecrysts (334 +/- 2 Ma, 341 +/- 2, and 348 +/- 2, where the age of 348 Ma maybe considered as derived from the source, i.e. xenocrysts). Migration of the parental magma from the mush reservoir zone occurred near the time of emplacement and culminated in the formation of an ephemeral magma chamber located in shallow levels, where Devonian and Carboniferous zircon autocrysts crystallized (382 +/- 5 Ma and 325 +/- 2 Ma, respectively). Age spectra reported within individual sample, favors the idea of a massive migration of magma when conditions were favorable (e.g., thermally matured crust). Notably, the Carboniferous geochronological data is strongly consistent with previous geochronological data recently reported for the granitic rocks of the Tabaquito batholith. Although this model supports a protracted magmatic system for the Devonian and Carboniferous subduction-related magmatism, previous and new isotopic data reveal a significant difference in the petrogenetic processes. While the Carboniferous arc magmatism shows significant juvenile material contribution, this is not the case for the Devonian magmatic arc, where isotopic data suggest an older continental lithosphere as the dominant source. These different sources are attributed to two contrasting geodynamic settings, with advancing and retreating oceanic slabs, respectively.

We present new petrographic, whole-rock geochemistry, and SHRIMP U - Pb zircon geochronological data of metabasic rocks interlayered as sills in the metasedimentary units of the Perau and Betara formations, Votuverava Group, Southern Ribeira Belt, Brazil. These formations overlie similar to 1.8 Ga Paleoproterozoic metagranitoids that represent basement inliers from the Paranapanema Craton. Petrography and whole-rock geochemistry allow the recognition of four groups, ranging from primitive to evolved compositions: i) cumulatic metadolerites (G1), ii) isotropic metadolerites (G2), iii) ortho-amphibolites (G3); and iv) ferroan ortho-amphibolites (G4). They exhibit tholeiitic subalkali basaltic composition, near-flat REE patterns, and signatures between N- and E-MORB. Fractional crystallization under low fO2 conditions is the main petrogenetic process controlling the magmatic evolution, as observed by Ti/V and Cr/Y ratio and tholeiitic trends. Crustal contamination signatures are observed through negative Nb anomaly, Th/Nb-Ti/V proxies trends, LILE enrichment, and, also, assimilated xenocryst zircons aged similar to 2.2 Ga. REE and trace element systematics indicate that the basic magmas were generated by similar to 20-10% partial melting of a model asthenospheric mantle source within spinel facies. TiO2/Yb-Nb/Yb and Nb/Yb-Zr/Yb ratio proxies and P-MORB metabasic rocks, previously described in the literature within the Votuverava Group, suggest a plume-influenced melt. A new SHRIMP U - Pb zircon age of 1448 +/- 11 Ma was determined for an ortho-amphibolite sample (G3 group). We propose an intracontinental tectonic setting for the genesis of the metadolerites whitin the Perau and Betara formations, suggesting that this extensional event is associated with the Paranapanema Craton rifting. Furthermore, the genesis of the studied metabasic rocks could be associated with a regional extensional event during Calymmian times (similar to 1.5-1.45 Ga), which generated basic magmatism in several other cratons, such as the Congo, S & atilde;o Francisco, Siberian, Laurentian, and China cratons, linked to the break-up of the Columbia Supercontinent.

The San Miguel marble is one of the only two carbonate rocks identified in the Paleoproterozoic basement of the Tandilia Belt (Argentina) and records the Lomagundi-Jatuli Event. The marble is scarcely limited in time and represents an opportunity to learn more about the geological processes that occurred during the Precambrian in the southern sector of the Rio de la Plata Craton and also about the evolution of the processes that took place during the Paleoproterozoic at the global level. This work presents the first U-Pb LA-ICP-MS determinations performed in detrital zircon grains of the San Miguel marble. The results indicate three main age groups that geochronologically constraint the sedimentary and metamorphic processes involved in the genesis of the marble, which are in accordance with the principal stages of the tectonic evolution defined for the Tandilia Belt basement. The first group, between 2543 +/- 23 Ma and 2358 +/- 22 Ma, represents sedimentation in the Siderian marine basins. The second group, between 2306 +/- 20 Ma and 2215 +/- 20 Ma, points out the metamorphic event that occurred in the Rhyacian period during the subduction stage. The third and youngest age group, between 2151 +/- 20 and 2017 +/- 28 Ma, would be associated with the collisional stage that occurred during the Transamazonian Cycle. In addition, the maximum and the minimum age of sedimentation of 2370 +/- 17 Ma and 2297 +/- 19 Ma (metamorphism), respectively, locate the San Miguel protolith genesis during a transitional period on the onset of the Lomagundi-Jatuli Event during a post glacial stage (Huronian Glaciation Event).

It is widely acknowledged that thermal models clearly demonstrate that crustal magma bodies should solidify rapidly upon emplacement. Small plutons can cool below the solidus in thousands of years, while even large plutons require hundreds of thousands of years, but not more than a million years. However, recent U-Pb zircon geochronological data contradict these results, strongly suggesting that magmatic systems are often characterized by protracted events. Therefore, a conceptual framework that reconciles thermal models and the geochronology data is necessary. The Devonian foreland magmatism of the Sierra de San Luis is made up of two distinctive suites, the Monzonite suite (<65 wt.% SiO2) and the Granite suite (>65 wt.% SiO2), both emplaced at ca. 3.7 kbar. Classification of the studied Devonian granitoids is debatable because they have a hybrid I- to A-type granite signature. Based on a robust geochronological U-Pb zircon dataset we corroborate the development of a protracted magmatic activity with three major crystallization events for this Devonian magmatism: 391 +/- 1, 384 +/- 1, and 379 +/- 2 Ma. Considering these geochronological data, we postulate the presence of a deep mush reservoir, where a prolonged magmatic activity, permitted the prolonged crystallization of antecrysts (ca. 395-384 Ma). Migration of the parental magma from the mush reservoir zone occurred near the time of emplacement and culminated in the formation of an ephemeral magma chamber located at shallow levels, where zircon autocrysts crystallized (ca. 379 Ma). Age spectra reported within individual samples support the idea of a massive migration of magma when conditions were favourable (e.g. thermally matured crust). Individual crystallization ages recorded by monazites hosted in two-mica granites are comparable to those obtained from zircons, supporting the presence of a long-lasting hot source. Additional geochronological data indicate that a later thermal event (ca. 353 Ma) could have partially affected some areas of the Devonian magmatic zircons promoting Pb loss, with subsequent partial resetting of the isotopic clock.

The mechanisms responsible for determining whether a magmatic system will generate a bimodal or monotonous intermediate volcanic suite are still widely debated in igneous petrology. Thus, the compositional characteristics of volcanic suites represent the ultimate reflection of their magmatic evolution and provide crucial insights into their remote volcanic and igneous plumbing systems. Decoding what these erupted compositions record is challenging however, and of paramount importance for volcanology, igneous petrology, and tectonic studies. This work employs an integrated petrological and thermal numerical modeling approach to identify the variables that modulate the compositional diversity registered in several volcano-tectonic settings, using two Neoproterozoic extensional rift basins in southern Brazil as case studies. Based on rhyolite-MELTS thermodynamic models of fractional crystallization, the resulting crystallization-differentiation curves of basaltic magmas indicate that the prevalence or scarcity of intermediate compositions in the volcanic record results from the thermodynamic control of differentiation patterns, whereas the numerical models also support the interplay with lithospheric heat transfer/maintenance processes. There is a well-known, yet underexplored, tendency of fractionating basaltic magmas to differentiate rapidly through intermediate compositions, possibly associated with a sudden increase in silica contents owing to Fe-Ti oxides crystallization and/or crystal productivity. This may explain the lack or scarcity of these compositions within predominantly bimodal volcanic suites, an observation known as the Daly Gap. The models presented in this contribution explore the nonlinear dependency between composition, crystallinity, and temperature (X-F-T) of differentiating basaltic magmas, which seems to be a common feature shared by alkaline, transitional, and even sub-alkaline basalts. When accounting for the considered thermic state of the medium they intrude into (ca. 300 to 800 degrees C) and the modeled accretion rates (ca. 0.01770 to 0.00354 m/yr) for intervals <= 300 ka, the models reveal that magma reservoirs undergoing crystallization-differentiation can only store intermediate compositions capable of erupting in relatively warm environments. Conversely, magma reservoirs with lower heat accumulation consist of alternating basic and silicic compositions, potentially giving rise to bimodal volcanic sequences. In these systems, compositional gaps are associated with increased crystal productivity over limited temperature intervals in the X-F-T space, coupled with relatively lower degrees of heat accumulation. Additionally, a subordinate compositional gap has been observed in the modeled silicic magmas, supporting our interpretation that increased crystal productivity results in subdued compositions along continuous liquid lines of descent. These nonlinear crystallization-fractionation patterns of basalts can also contribute to the compositional disparity between the volcanic and plutonic realms at arc settings.

Based on a relevant geochronological U-Pb zircon dataset (n = 47) from a sample (PBL-109) of the Cerro Punta Blanca pluton (CPB), which is part of a calc-alkaline suite, we corroborate the development of protracted magmatic activity with three major crystallization events for this Permian magmatism: 278 f 1, 283 f 2, and 289 f 2 Ma, which outcrop in the Cordon del Portillo, Cordillera Frontal (CF) of Argentina. These ages can be assigned to the lower section of the magmatic record of the Choiyoi magmatism (ca., 290-265 Ma), while the age of 289 Ma represents the oldest known age for the Choiyoi, indicating the start of this magmatism during the Artinskiense. Considering these geochronological data, we postulate the presence of a deep mush reservoir where protracted magmatic activity permitted the prolonged crystallization of antecrysts (ca. 283-289 Ma). Migration of the parental magma from the mush reservoir zone occurred near the time of emplacement and culminated in the formation of an ephemeral magma chamber at shallow levels, where zircon autocrysts crystallized (ca. 278 Ma). Age spectra reported within individual samples support the idea of massive magma migration when conditions were favorable (e.g., thermally matured crust). In this view, the studied "older" Choiyoi magmatism represents a continuous magmatic event lasting 11 Ma and corresponds to a single magmatic episode rather than different periods of magmatic activity and subsequent emplacements. A later alkali-calcic magmatic event is recorded at 265 f 4 Ma from a sample of the Cerro Bayo pluton (MH-0113), which could represent the end of the lower section of the Choiyoi magmatism. Whole-rock Sm-Nd, Rb-Sr, and Lu-Hf data in zircon, along with ages reported for the studied igneous and inherited zircon from the CPB; together with isotopic data and ages from the detrital zircon found in the Carboniferous accretionary complex of Chile, indicate that the source of the Permian parental magma in this region was a heterogeneous continental crust mainly formed by Devonian and Carboniferous rocks, related probably to a magmatic arc. However, some contribution from the Carboniferous accretionary complex of Chile to the parental magma should be consider.

Cordilleran Granitic batholiths or Andean/Cordilleran batholiths serve as plutonic expressions of continental arcs, offering valuable insights into the processes that operate in large silicic magmatic systems at subduction environments. This work presents a comprehensive geochronological study of the Carboniferous Tabaquito batholith in the Frontal Cordillera of western Argentina, which is the best exponent of the Carboniferous arcrelated magmatism in this region. Using new data obtained through LA-MC-ICP-MS and comparing it with previously published data (LA-MC-ICP-MS and SHRIMP techniques), we identify five distinct magmatic events in the Tabaquito batholith: 325 +/- 2 Ma; 332 +/- 2 Ma; 337 +/- 2 Ma; 346 +/- 1 Ma, and 362 +/- 2 Ma. The 325 Ma event is considered as the best estimate of the crystallization age during the emplacement. The 332 Ma, 337 Ma, 346 Ma and 362 Ma events suggest the presence of zircon antecrysts, implying a complex magmatic system that worked for a protracted time lapse of ca. 40 Myr, or ca. 15 Myr if we consider the ages of 346 and 362 Ma as xenocrysts from a source like the Potrerillos pluton (346 +/- 3 Ma to 356 +/- 3 Ma), which was interpreted in previous studies as possible source of the parental magmas of the Tabaquito batholith. Furthermore, it has been also identified inherited zircons with ages older than ca. 370 Ma that are consistent with the detrital zircon pattern obtained for the country rock. Inherited zircon ages from the referred country rock yield a maximum deposition age estimated at 387 Ma that is consistent with the fossil ammonoids record, indicating that the granitic rocks were emplaced in Devonian rocks.

The Neoproterozoic Dom Feliciano Belt, the southern portion of the Mantiqueira Province, has over half of its area composed of granitic rocks, forming a granitic belt from Uruguay to the southern region of Brazil. The continuum of the batholith is interrupted by the Phanerozoic cover of the Paran & aacute; Basin. The Florian & oacute;polis Batholith is composed of granitic suites that crystallized between 640 and 580 Ma, with its northern limit defined by the Major Gercino Shear Zone. The batholith crops out about 15 km west of the current border of the Paran & aacute; Basin, along a valley sculpted by the Adaga and Lessa rivers. The importance of this region lies in the limited information about the continuity of the batholith beneath the sedimentary cover. This work aims to characterize field and petrographic features and crystallization age using U-Pb laser ablation-inductively coupled plasma mass spectrometry methodology on zircon and titanite of granitoid rocks that crop out in the Picadas region. These rocks are coarse to medium-fine-grained monzogranites, porphyritic to equigranular, with biotite and hornblende as the mafic phases. The U-Pb results showed the existence of Paleo, Meso, and Neoproterozoic (Tonian) inheritances and crystallization events at ca. 630-624 Ma and at 598 Ma.