Petrogenesis of the Langdu High-K Calc-Alkaline Intrusions in Yunnan Province: Constraints from Geochemistry and Sr-Nd Isotopes

The Langdu high-K calc-alkaline intrusions are located in the Zhongdian area, which is the southern part of the Yidun island arc. These intrusive rocks consist mainly of monzonite porphyry, granodiorite, and diorite porphyry. The K20 content of majority of these rocks is greater than 3%, and, in the K20-SiO2 diagram, all the samples fall into the high-K calc-alkaline to shoshonitic fields. They are enriched in light rare earth elements （LREEs） and depleted in heavy rare earth elements （HREEs; LaN/YbN = 14.3-21.2）, and show slightly negative Eu anomalies （6Eu = 0.77-1.00）. These rocks have high K, Rb, Sr, and Ba contents; moderate to high enrichment of compatible elements （Cr = 36.7-79.9 ppm, Co = 9.6-16.4 ppm, and MgO = 2.2%-3.4%）; low Nb, Ta, and Ti contents, and characteristic of low high field strength elements（HFSEs） versus incompatible elements ratios （Nb/Th = 0.75, Nb/La = 0.34） and incompatible elements ratios （Nb/U = 3.0 and Ce/Pb = 5.1, Ba/Rb = 12.0）. These rocks exhibit restricted Sr and Nd isotopic compositions, with （87Sr/S6Sr）i values ranging from 0.7044 to 0.7069 and ENd（t） values from -2.8 to -2.2. The Sr-Nd isotope systematic and specific trace element ratios suggest that Langdu high-K calc-alkaline intrusive rocks derived from a metasomatized mantle source. The unique geochemical feature of intrusive rocks can be modeled successfully using different members of a slightly enriched mantle, a slab-derived fluid, and terrigenous sediments. It can be inferred that the degree of partial melting and the presence of specific components are temporally related to the tectonic evolution of the Zhongdian island arc. Formation of these rocks can be explained by the various degrees of melting within an ascending region of the slightly enriched mantle, triggered by the subduction of the Garz^--Litang ocean, and an interaction between the slab-derived fluid and the terrigenous sediments.

Petrological and Structural Approach to Understanding the Mechanism of Formation and Development of Paleoproterozoic Calc-Alkaline Volcanic Rocks of West Africa’s Craton: An Example of the Mako and Foulde Groups (Kedougou Inlier in Western Senegal)

The calc-alkaline volcanic formations in the western part of the Kedougou-Kenieba inlier crop out in three complexes: the Foulde in the North and the areas of Mako and Baniomba in the South. These complexes which either combine with the tholeiites or cut across the sedimentary formations are composed of thin veins and massive lava flows. They have many petrographic similarities and show chemical characteristics that resemble those of island-arc rocks. At the tectonic level, the D1 deformation phase preceding the formation of the basins and the transpressive tectonics including an oblique convergence may account for the structural evolution of the Mako volcanic belt. Its occurrence in different basins may be evidenced by the composition of some lithophilic components like the Sr, Ba, U, Rb and the composition of clinopyroxenes enriched in TiO2, FeO, Na2O in the Foulde calc-alkaline volcanic rocks that developed in a sedimentary environment.

Geochemical characteristics and origin of the Neoproterozoic high-K calc-alkaline granitoids in the northern part of Mandara hills,northeastern Nigeria

The high-K calc-alkaline granitoids in the northern part of the Mandara Hills are part of the wellexposed post-collisional plutons in northeastern Nigeria.The calc-alkaline rock association consists of quartz monzodiorite,hornblende biotite granite,biotite granites and aplite which intruded the older basement consisting mainly of low-lying migmatitic gneisses and amphibolites during the Neoproterozoic Pan-African Orogeny.Petrological and geochemical studies have revealed the presence of hornblende,iron oxide,and metaluminous to slightly peraluminous characteristics in the granitoids which is typical of I-type granite.The granitoids are also depleted in some high field strength elements(e.g.Nb and Ta) as well as Ti.Plots of Mg#versus SiO2 indicate that the granite was derived from partial melting of crustal sources.Lithospheric delamination at the waning stage of the PanAfrican Orogeny possibly triggered upwelling of hot mafic magma from the mantle which underplated the lower crust.This,in turn,caused partial melting and magma generation at the lower to middle-crustal level.However,the peculiar geochemical characteristics of the quartz monzodiorite especially the enrichment in compatible elements such as MgO,Cr,and Ni,as well as LILE element(e.g.K,Ce,Cs,Ba,and Sr),signify that the rock formed from an enriched upper mantle source.The emplacement of high-K granites in the Madara Hill,therefore,marked an important episode of crustal reworking during the Neoproterozoic.However,further isotopic work is needed to confirm this model.

Petrogenesis of Late Mesozoic Calc-Alkaline Lamprophyres from Sulu UHP Terrane, Eastern China: Implications to Paleo-Pacific Plate Subduction and Destruction of the North China Craton

Destruction of the North China Craton has caused extensive concern on its multiple potential mechanisms including thermal erosion,chemical erosion and delamination.It is widely accepted that thinning of the

Early Paleozoic basement diorite of arc-magmatism from Kutch basin, Western India

In this study,we report for thefirst time an Early Palaeozoic basement diorite from the drilled well Nirona-A in the Banni Half-Graben of the Kutch basin,western India.The 40Ar–39Ar dates provided a plateau age of 441.84±2.66 Ma and another pseudo plateau of 441.28±5.82 to 388.08±16.65 Ma for the basement diorite.These ages constrain the basement formation age to the Late Ordovician-Early Silurian period.The obtained basement ages are correlatable with the later part of Cambro-Ordovician alkaline magmatism that has been reported from the Huqf area in Central Oman,whereas their lithological and petrographic correlativity with base-ment diorites occurring in the Dinsi Body of Nagar Parkar igneous complex in Pakistan can also be envisaged.The geochemical studies characterized the diorite with enrich-ment of LILE(Rb,Ba,and K)and LREE(La,Ce,Nd),strong depletion of HFSE(Nb,Sr,P,and Ti),along with weakly negative Eu anomalies.The geochemical signatures indicate their petrogenetic affiliation with mantle-derived magmas,as well as their tectonic setting to be arc-related,having post-collisional continental-arc type affinity.The*440 Ma basement of Kutch,therefore,appears to rep-resent the later thermal event associated with the reworked Neoproterozoic subduction-related suite from Greater India’s northwest edge,which has implications for Gond-wana assembly in the northwest Indian subcontinent.

Lamprophyre Rocks in the Nassara Gold Deposit, Southwest Burkina Faso: Characteristics and Implication for Mining Exploration

The lamprophyres are late dykes that cut the formations hosting the gold mineralization in the Nassara deposit. They are geographically and spatially related to most orogenic gold deposits. It is with the aim of characterizing them and seeing their implications for exploration that this work is carried out. To achieve our objective, petrographic studies and chemical analyses of minerals (pyroxenes, amphiboles, feldspars, chromite) and geochemical analyses of total rock were carried out. These studies have enabled us to classify the Nassara lamprophyres as calc-alkaline lamprophyres of the spessartite type. The Cr, Co, Ni and Mg enrichment of these rocks would indicate a depleted mantle source, with LILE enrichment by fluids probably related to metasomatic activity. The various diagrams show that they are depleted in HREE and enriched in LREE. The high Nb/Ta ratios in our data indicate metasomatic activity probably linked to amphibole and rutile in the mantle prior to melting. The geodynamic context of spessartite-type lamprophyres indicates a signature linked to late-orogenic to post-collisional subduction. They are late-orogenic to post-collisional lamprophyres enriched in compatible elements (Cr, Ni, Co) and display a negative Ta-Nb-Ti (TNT) anomaly. The frequent association of these lamprophyre dykes with the deposits does not indicate the source of the gold for these deposits, but rather zones of crustal permeability capable of draining hydrothermal fluids at the time of emplacement. Good mapping of lamprophyre dykes, especially in shear zones, could therefore guide prospecting and identify potential zones of hydrothermal fluid circulation.

Cenozoic Adakite-type Volcanic Rocks in Qiangtang,Tibet and Its Significance

Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.

Ordovician Granitoids and Silurian Mafic Dikes in the Western Kunlun Orogen, Northwest China:Implications for Evolution of the Proto-Tethys

The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(^(87)Sr/^(86)Sr)_i value of 0.7129–0.7224, ε_(Nd)(t) values of -9.3 to -7.0 and zircon ε_(Hf)(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial ^(87)Sr/^(86)Sr ratios of 0.7101–0.7152 and ε_(Nd)(t) values of -3.8 to -3.4 and zircon ε_(Hf)(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys.

U-Pb geochronology and geochemistry of late Palaeozoic volcanism in Sardinia(southern Variscides)

The latest Carboniferous to lower Permian volcanism of the southern Variscides in Sardinia developed in a regional continental transpressive and subsequent transtensile tectonic regime.Volcanism produced a wide range of intermediate-silicic magmas including medium-to high-K calc-alkaline andesites,dacites,and rhyolites.A thick late Palaeozoic succession is well exposed in the four most representative Sardinian continental basins(Nurra,Perdasdefogu,Escalaplano,and Seui-Seulo),and contains substantial stratigraphic,geochemical,and geochronological evidence of the area's complex geological evolution from the latest Carboniferous to the beginning of the Triassic.Based on major and trace element data and LA-ICP-MS U-Pb zircon dating,it is possible to reconstruct the timing of postVariscan volcanism.This volcanism records active tectonism between the latest Carboniferous and Permian,and post-dates the unroofing and erosion of nappes in this segment of the southern Variscides.In particular,igneous zircon grains from calc-alkaline silicic volcanic rocks yielded ages between299±1 and 288±3 Ma,thereby constraining the development of continental strike-slip faulting from south(Escalaplano Basin)to north(Nurra Basin).Notably,andesites emplaced in medium-grade metamorphic basement(Mt.Cobingius,Ogliastra)show a cluster of older ages at 332±12 Ma.Despite the large uncertainty,this age constrains the onset of igneous activity in the mid-crust.These new radiometric ages constitute:(1)a consistent dataset for different volcanic events;(2)a precise chronostratigraphic constraint which fits well with the biostratigraphic data and(3)insights into the plate reorganization between Laurussia and Gondwana during the late Palaeozoic evolution of the Variscan chain.

Petrologic and geochemical characterization and mineralization of the metavolcanic rocks of the Heib Formation,Kid Metamorphic Complex,Sinai,Egypt

Metavolcanic rocks hosting base metal sulphide mineralization, and belonging to the Kid Metamorphic Complex, are exposed in the Samra-Tarr area, Southern Sinai. The rocks consist of slightly metamorphosed varicolored porphyritic lavas of rhyolite-to-andesite composition, and their equivalent pyroclastics. Geochemically, these metavolcanics are classified as high-K calc-alkaline, metaluminous andesites, trachyandesites, dacites, and rhyolites. The geochemical characteristics of these metavolcanics strongly point to their derivation from continental crust in an active continental margin. The sulphide mineralization in these metavolcanics occurs in two major ore zones, and is represented by four distinct styles of mineralization. The mineralization occurs either as low-grade disseminations or as small massive pockets. The associated hydrothermal alterations include carbonatization, silicification, sericitization and argillic alterations. The base metal sulphide mineralization is epigenetic and was formed by hvdrothermal solutions associated with subduction-related volcanic activity.

First Evidence of Lamprophyric Magmatism from the Konya Region, Turkey:a Genetic Link to High-K Volcanism

In the vicinity of Konya （Turkey）,mafic,micro-porphyritic sub-volcanic rocks intrude into the Mesozoic units,which represents the only example of such a rock type in the region.40Ar/39Ar dating of two whole rock samples from the sub-volcanics gave ages of 13.72±0.13 and 12.40±0.11 Ma,suggesting temporal association to the Late Miocene-Pliocene high-K calc-alkaline volcanism in the region.The mineral chemistry and geochemical data permit us to classify the rocks as ＂minette＂ lamprophyres.They include diopside and phlogopite phenocrysts in a microcrystalline groundmass composed of sanidine,phlogopite,diopside and titano-magnetite.Segregation and ocelli-like globular structures occur commonly in the samples.In terms of major elements,the lamprophyres are calcalkaline,and potassic to ultrapotassic rocks.All the lamprophyres display strong enrichments in LILE （Rb,Ba,K,Sr）,radiogenic elements （Th,U） and LREE （La,Ce） and prominent negative Nb,Ta,and Ti anomalies on primordial mantle-normalized trace element diagrams.Geochemical data suggest that the lamprophyres and high-K calc-alkaline rocks in the region derived from a subduction-modified lithospheric mantle source affected by different metasomatic events.Lamprophyric magmatism sourced phlogopite-bearing veins generated by sediment-related metasomatism via subduction,but high-K calc-alkaline magmas are possibly derived from a mantle source affected by fluid-rich metasomatism.

The inception of a Paleotethyan magmatic arc in Iberia

This paper presents a compilation of recent U-Pb （zircon） ages of late Carboniferous-early Permian （LC EP） calc-alkaline batholiths from lberia, together with a petrogenetic interpretation of magma generation based on comparisons with Mesozoic and Tertiary Cordilleran batholiths and experimental melts. Zircon U-Pb ages distributed over the range ca. 315-280 Ma, indicate a linkage between calc-alkaline magmatism, Iberian orocline generation and Paleotethys subduction. It is also shown that Iberian LC-EP calcalkaline batholiths present unequivocal subduction-related features comparable with typical Cordilleran batholiths of the Pacific Americas active margin, although geochemical features were partially obscured by local modifications of magmas at the level of emplacement by country rock assimilation. When and how LC-EP calc-alkaline batholiths formed in Iberia is then discussed, and a new and somewhat controversial interpretation for their sources and tectonic setting （plume-assisted relamination） is suggested. The batholiths are proposed to have formed during the subduction of the Paleotethys oceanic plate （Pangaea self-subduction） and, consequently, they are unrelated to Variscan collision. The origin of the Iberian batholiths is related to the Eurasian active margin and probably represents the inception of a Paleotethvan arc in the core of Pangaea.

Petrology and Geochemistry of Dikes in the North of Saveh in Iran

Dikes in the north of Saveh are located in a region with an area of approximately 200 square kilometers, in a distance of approximately 100 kilometers south of Tehran. Dikes mentioned in terms of petrological composition, are divided into two categories: alkaline and intermediate to acidic. Alkaline dikes include: andesitic basalt and andesite and intermediate to acidic dikes include: trachyte and trachyandesite. In terms of geochemical, dikes in the north of Saveh have a dual nature of alkaline and calc-alkaline. Both groups are derived from more enrichment source than primitive mantle. Despite similarity of pattern of both groups, varieties of alkaline having less silica, in the elements Sr, Ti, Nb and Ta show more enrichment and in the elements Hf, Rb, Th, K show less enrichment than varieties of calc-alkaline.

Petrography, Geochemistry and Petrogensis of Basal Flow from Ar-Rabba Area, Central Jordan

Thirty basaltic rock samples collected from a central Jordan at Ar-Rabba area were studied. The samples cover about 20 km2 from the Al-Rabba basalt flow. The Al-Rabba Basalt (RB) introduced Miocene to Pleistocene period. Petrography, Geochemistry and Petrogenesis investigations were carried out for the RB. The petrography analyses of the RB rocks are composed of plagioclase, pyroxene, olivine, opaque minerals (magnetite), and including secondary minerals calcite, iddingsite, and clay. The RB rocks have low range of major and trace elements concentrations, and under sodic alkaline magma series. The geochemical analysis data of RB indicated that RB was derived from a slightly fractionation magma as reflected by high MgO concentration range between (5.4 to 11.7 wt%), and Mg number from 42 to 63.8, and high concentration Cr (18 - 385 ppm), Ni (160 - 364 ppm) and low silica content ( 41.79 - 49.87 wt%). The chemical classification of RB is divided into basaltic, calc-alkaline to alkali basalt. The tectonic setting of RB is explained by using discrimination diagrams, Ti-Zr-Y, Ti-Zr-Sr and MgO-FeO(tot)-Al2O3, the RB plotted within the plate, calc-alkali and continental basalt respectively. The Rayleigh fractionation equation modeled for Sr and Ba vector diagram indicated the RB had fractionation for clinopyroxene, orthpyro-xene, olivine and trace of plagioclase.

Pozzolanic Activity of Old Volcanic Tuffs of Mako Area (Senegal-Oriental, West African Craton): An Economic and Environmental Interest

The volcanic tuffs of Senegal-Oriental in Mako area are produced during a calc-alkaline volcanism which occurs in this region and which is dated from about 2.3 - 1.95 Ga. Despite their altered appearance, the X-Ray diffractions show mineral paragenesis: Quartz-Kaolinite-Illite and an important amorphous phase. On the Ternary Keil-Rankin diagram for the CaO-SiO2-Al2O3 the volcanic tuffs of Mako area are situated between pozzolan and the fly ash. The difference between silica and lime is greater than 34% in these volcanic tuffs. In this study, they have been mixed with Portland cement to obtain pozzolanic cements respectively with 20%, 30%, 35% and 40% of addition of volcanic tuffs. The pozzolanic reactivity is highlighted by the compressive strength increase until 90 days of conservation in water. It supposes that the vitreous phase of the volcanic tuffs reacts with the free CaO (CaOf) of Portland cement to produce new hydrated minerals. This study has a positive economic and environmental impact. Because the time of grinding of pozzolanic cements is reduced. Also, the addition of volcanic tuffs reduces the production of clinker, then the CO2 emission.

Petrography and Geochemical Characteristic of Koohrig Intrusive Rocks in Kerman, Iran

Koohrig intrusive mass is located in the east of Rafsanjan, Kerman Province, Iran and it is part of because it has cut the sandstone, limestone, shale units and conglomerate of Upper Cretaceous. Its intrusive rock includes quartz, plagioclase and alkali feldspar and its ferromagnesian mineral which is biotite has changed into chlorite. This Intrusive mass is characterized by the presence of metamorphic geochemical studies led to the detection of granite and granodiorite and quartz monzonite rocks.

Geochemical Classification and Geotectonic Setting of Granitic Gneisses from Southeastern Margin of Western Nigeria Basement

Chemical whole-rock major oxides and some trace element analyses were done on granitic-gneiss rocks from Dagbala-Atte District,located on the southeastern margin of western Nigeria Basement Complex.This was meant to classify the rocks and to understand the tectonic setting in order to evaluate their crustal evolution.The chemical analyses were done using inductively-coupled plasma mass spectrometer.From the results obtained,these rocks classified into calc-alkaline to shoshonite series with metaluminous to peraluminous varieties.They are I-type granitoids of feroan composition.The granitic gneisses formed from metamorphism of granite and granodiorite.Tectonically,most of the rock samples plotted in the field of island arc,continental arc and continental-collisional granitoids,which indicated that the protolith granite and granodiorite are orogenic and are arc related inferring arc tectonic setting.

Petrographic Characteristics and Geochemistry of Volcanic Rocks in the Kyaukmyet Prospect,Monywa District,Central Myanmar

The Kyaukmyet prospect lies approximately 5 km ENE of the high-sulfidation Kyisintaung copper-gold deposit,Monywa district,central Myanmar.Geologically,the research area is remarked by magmatic extrusion that occurred during the Late Oligocene to Middle Miocene of Magyigon Formation which led to the outcrops of volcanic rocks.Study detailed on petrographical and geochemical of the Kyaukmyet volcanic rocks has not been performed before the present work.The principal aim of this paper is to document the petrographical and geochemical characteristics of volcanic suite rocks exposed in the Kyaukmyet prospect.The results of this data have provided insight into the origin of the rocks and petrogenetic processes during evolution.Petrographically,all the studied volcanic rocks in the research area show that trachytic and porphyritic textures with phenocrysts of quartz,plagioclase,and K-feldspar which are embedded in a fine to medium grained groundmass.The accessory minerals of this rock consist of biotite,chlorite and opaque mineral.Geochemically,these volcanic rocks having calc-alkaline nature and classified as volcanic field(rhyolite)as well as volcanic arc setting.Based on the chondrite normalized spider diagram,LREE has enriched to HREE in this area which indicated negative Eu anomaly and subduction tectonic setting.

The age and tectonic environment of the rhyolitic rocks on the western side of Wuyi Mountain,South China

During the geological survey of the metamorphic rocks in Xingning-Wuhua region on the western side of Wuyi Mountain, South China, we discovered the Neoproterozoic rhyolite and rhyolitic greywacke for the first time that outcrop in the Proterozoic metamorphic rocks near Jingnan Town of Xingning County, eastern Guangdong Province. A systematic research on petrology, geochemistry and geochronology of rhyolitic rocks was conducted to understand their tectonic setting and formation age. The Jingnan rhyolite is interbedded with a coeval greywacke, with a total thickness of 60 m; both rhyolite and greywacke display a similar folding and metamorphic pattern. Meta-rhyolite consists of groundmass and phenocrystals including sanidine, orthoclase, and quartz with distinct undulose extinction; the groundmass has been recrystallized into fine-grain feldspar, quartz and sericite aggregation. Meta-greywacke is composed of crystallinoclastic grains (sanidine, orthoclase, quartz and oligoclase) and clay groundmass. Zircon grains used for the SHRIMP U-Pb analysis are light brown-colored and euhedral or subeuhedral. Dating data suggest two age groups; eight grains of magmatype zircon with an idiomorphic form yield an age of 972±8 Ma, and the other seven weakly corroded grains of zircon with euhedral to subeuhedral shape construct an average age of 1097±11 Ma, which were captured from older rocks by an uplifting magma, implying that a late Mesoproterozoic basement exists in the Nanling region. In addition, one Paleoproterozoic age, 2035±11 Ma, is obtained from a rounded detrital zircon, indicating that a Paleoproterozoic thermal event took place in the South China. Geochemically, the Jingnan rhyolitic rocks are characterized by high K2O content, intermediate Al2O3 content, with the ACNK value 0.98―1.11, and belonging to high-K alkaline series. They are rich in ΣREE, Rb, Th and Ce, depleted in Ba, Sr, Eu, Ti, P and Nb-Ta, and with moderate negative Eu and Sr anomalies. These features indicate that the Jingnan volcanic rocks have an affinity of continental arc that is similar to those of acid volcanic rocks in the SE-China Coastal Region, in other words, a Neoproterozoic tectonomagma event might have taken place in the western Wuyi region, leading to an eruption of high-K calc-alkaline granitic magma.

Petrogenesis of Granites from the Ediacaran Socorro Batholith,SE Brazil:Constraints from Zircon Dating,Geochemistry and Sr-Nd-Hf Isotopes

Whole rock elemental and Sr-Nd isotope geochemistry and in situ zircon Hf isotope geochemistry were used to identify the sources of the Neoproterozoic granites from the Socorro batholith,Socorro-GuaxupéNappe(SGN),South Brasilia Orogen,Brazil.Zircon trace elements and Hf isotope geochemistry provided information about sources and crystallization(T,f_(O2))conditions.Three main types of granites built the bulk of the batholiths,beginning with probably pre-collisional~640–630 Ma charnockites,and ending with~610 Ma voluminous post-collisional high-K calc-alkaline(HKCA)Ⅰ-type granites(Bragan?a Paulista-type).Several types of leucogranites were generated from 625 to 610 Ma,spanning the interval from collisional to post-collisional tectonics.Two charnockite bodies occur in the study area:the~640 Ma Socorro charnockite has remarkable chemical similarities with Braganca Paulista-type granites,but higherε_(Nd)(t)=-6.1 and average zirconε_(Hf)(t)=-9.1 and lower^(86)Sr/^(87)Sr_(t)(0.7093)values,indicative of more juvenile and water-poor source.The~633 Ma Atibaia charnockite has distinct geochemical signature(lower Mg^(#)and Sr content;higher Zr),more negativeε_(Nd)(t)=-14.1,similar average zirconε_(Hf)(t)=-8.9,and much higher^(86)Sr/^(87)Sr_(t)=0.7197,probably reflecting a larger component from old crust.The predominant~610 Ma Bragan?a Paulista-type granites were emplaced in a post-collisional setting,and correspond to porphyritic biotite-hornblende monzogranites of high-K calc-alkaline character with 61 wt.%–67 wt.%SiO_(2),high Mg^(#)(39–42),Sr/Y(19–40),La/Yb(12–69),highly negativeε_(Nd)(t)(-12.3 to-12.9)and zirconε_(Hf)(t)(-12 to-17)and^(87)Sr/^(86)Sr_(t)=0.7119–0.7131.These features are interpreted as indicative of magma generation in a thickened crust,where melts from enriched mantle sources emplaced in the lowermost crust,heated host old continental crust rocks(gneisses and granulites)and partially mixed with their melting products.Leucogranite plutons(SiO_(2)>72 wt.%)occurring in the southern portion of the batholith have a range of geochemical and isotope signatures,reflecting melting of crustal sources in space and time between~625 Ma(Bocaina Pluton)and~610 Ma(Bairro da Pedreira Pluton).Highly negativeε_(Nd)(t)(-16.2)and average zirconε_(Hf)(t)=-16,and high^(87)Sr/^(86)Sr_(t)(0.7156–0.7171)are consistent with relatively old orthoand paragneiss sources similar to those which generated regionally abundant migmatites and anatectic granites in the collisional to post-collisional setting.