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The difference in radiation damage retained in unknown and reference zircons, caused by the α-dose matrix effect, has been considered as a great influence on the accuracy and precision of zircon U–Pb dating as found from LA-ICP-MS and SIMS analysis. This study aims to explore the effect of high-temperature thermal annealing (>1300 °C) on the optimization of the U–Pb dating of standard zircons, such as Sri Lanka, Plešovice, and Qinghu zircons, with heterogeneous radiation damage. Raman spectroscopy was employed to investigate the structural state of Sri Lanka zircons that were annealed at 100 °C to 1300 °C at various times (isochronal and isothermal annealing), indicating that annealing at 1400 °C for 96 h can result in a nearly complete crystalline state for zircons with a low-moderate degree of radiation damage. SIMS U–Pb isotopic analyses of unannealed and annealed Sri Lanka zircon grains revealed that the homogeneity of sample SL-3 annealed at 1300 °C with a 206Pb/238U age of 572.4 ± 4.4 Ma (2σ, MSWD = 0.08) is greater than those of the sample SL-2 annealed at 850 °C with 206Pb/238U age of 575.0 ± 4.5 Ma (2σ, MSWD = 0.57) and sample SL-1 unannealed with 206Pb/238U age of 575.3 ± 4.3 Ma (2σ, MSWD = 0.30). Furthermore, the results of LA-ICP-MS U–Pb ages and trace element concentrations for Plešovice and Qinghu zircons indicate that high-temperature thermal annealing can reduce the distribution of trace element composition and the scatters of the 206Pb/238U ages with MSWD decreasing by 82% and 71%, respectively, despite the annealed zircons yielding slightly younger 206Pb/238U ages than unannealed zircons. This approach provides new insights into acquiring homogeneous U–Pb ages of standard zircons with heterogeneous radiation damage, which would be useful to calibrate and obtain unknown zircon U–Pb dating with better precision and accuracy. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogenic Belt (E-KOB) documents successive subduction and accretion processes of the Paleo-Tethyan Ocean. However, the tectonic regime of the E-KOB at the late orogenic stage remains ambiguous. This study presents new results of whole-rock geochemistry and zircon U-Pb-Hf isotopes of the Xidatan pluton in the southern E-KOB. Detailed investigation reveals that the pluton is composed of quartz monzodiorite, host monzogranite, and igneous microgranular enclaves (IMEs). Zircon U-Pb dating results suggest that they are coeval magmatic rocks emplaced at ca. 206–203 Ma. Geochemical studies reveal that the quartz monzodiorite and IMEs share a common magma source, evidenced by consistent compositions of major elements, congruently enriched LREEs and LILEs, and consistently moderately depleted HFSEs and HREEs. Enriched to slightly juvenile zircon Hf isotopes (εHf(t) = −4.24 to +0.49) indicate that the primitive magmas of the quartz monzodiorite and IMEs involve the addition of mantle-derived magmas. The quartz monzodiorite and IMEs have identical ages, and consistent isotope features with the host monzogranite, together with the observation of ingestion of xenocrysts from host felsic rocks into the IMEs indicating that they were produced through the mixing of the mantle-derived mafic magmas and host felsic magmas. In contrast, The host monzogranite has moderately high SiO2 and Na2O+K2O, but low Fe2O3T and MgO contents. It shows crust-like trace element patterns such as strong enrichments in LREEs and LILEs, but remarkable depletions in HREEs. Along with enriched zircon Hf isotopes (εHf(t) = −3.51 to −0.25), the host monzogranite was most likely to have originated from partial melting of lower crustal mafic rocks induced by underplated mantle-derived magmas. Considering abundant Late Triassic igneous rocks across the E-KOB, these new data provide further evidence that the Late Triassic magmatism in the E-KOB may be related to the delamination of thickened orogenic root under an extensional setting. [ABSTRACT FROM AUTHOR]

The Qinling Orogenic Belt was formed by multi-stage convergence and subsequent collision between the North China Block and South China Block during the Palaeozoic to Late Triassic. Following the collision between the South Qinling Belt and the South China Block in the Late Triassic, the whole Qinling Orogenic Belt evolved into an intracontinental orogeny. However, the exact termination time of the Late Mesozoic intracontinental contractional deformation and the tectonic transformation from compression to extension remains unclear. The extensional shear zone developed in the West Qinling Orogenic Belt provides a crucial clue to revealing the tectonic transformation and uplift and exhumation of the orogenic belt. This study focuses on kinematics, deformation temperature, and geochronology of the shear zone in the West Qinling Orogenic Belt through detailed field structural analysis and laboratory analysis. The Taibai shear zone (TBSZ), located in the West Qinling Orogenic Belt, cuts across the Qinling Orogenic Belt along the NE–NEE direction and separates the Taibai pluton in the east from the Baoji pluton in the west. The NE–NEE-striking TBSZ is an extensional shear zone showing a top-to-the-NW sinistral shear sense. The TBSZ was formed under the high greenschist–low amphibolite facies conditions (300–550°C) in the middle-upper crust level (8–15 km). Zircon U–Pb dating and biotite and muscovite 40Ar/39Ar dating indicate that the TBSZ occurred at 120–113 Ma. The extensional TBSZ and normal faults on its hanging wall indicate the tectonic transformation and the extensional collapse of the Mesozoic intracontinental orogenic belt during the late Early Cretaceous. The Cretaceous extensional collapse of the Qinling Orogenic Belt also led to the rapid uplift and exhumation of the Taibai pluton and the North Qinling Belt in the east. [ABSTRACT FROM AUTHOR]

The Dongnan Cu–Mo deposit, located in the southeast of the Zijinshan ore field (the largest porphyry–epithermal system in Southeast China), represents the complex magmatic and metallogenesis events in the region. The petrogenesis and metallogenesis of granitoids from the deposit are not determined, especially the interactions between ore-bearing (granodiorite porphyry) and barren samples (granodiorite and diorite). In the paper, the whole rock geochemical features shared a similar affinity to the middle-lower content and revealed that they derived from partial melting of the Cathaysian basement with the contribution of mantle materials, even represented that they generated in the plate subduction; LA-ICP-MS zircon U–Pb ages show that these granodiorites, granodioritic porphyry and diorite, were generated during 114–103 Ma. The ore-bearing samples mostly presented εHf(t) of negative values (peak value is −4 to −3) with old two-stage Hf model ages (tDM2) (peak value is 1.10–1.15 Ga), while the barren sample showed slightly negative εHf(t) (peak value is −1 to 0) values with young tDM2 (peak value is 1.00–1.05 Ga). The value of zircon Ce4+/Ce3+ ratio mostly higher than 450 was first verified for the ore-bearing samples in the Dongnan Cu–Mo deposit, and the values of ore-bearing were found to be higher than those from the barren, which suggests that the ore-bearing formed in more oxidized parental magma with higher oxygen fugacity. Based on the geochemical characteristic of the element and isotope, we concluded that the Early Cretaceous multi-phases magmatic activities, low melting temperature and low pressure of pluton, and high oxygen fugacity of zircon, were the favorable conditions for metallogenesis of Dongnan Cu–Mo deposit. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogenic Belt (E‐KOB) of the northern Tibetan Plateau is an accretionary orogenic belt, which has experienced complicated tectonic evolutionary processes of the Proto‐ to Palaeo‐Tethys Ocean. The Muztagh‐Buqingshan‐Anemaqen ophiolitic mélange zone (MBAM) is an accretionary complex related to the northward subduction of the Tethyan Ocean. Numerous intrusions outcropped in MBAM have witnessed the long‐term subduction‐accretionary process and thus site the key to comprehending the tectonic evolution of the E‐KOB, as well as the Tethyan Ocean. In this study, petrological, geochronological, and geochemical studies of the Marzheng diorites in the MBAM were carried out to explore the Early Palaeozoic tectonic evolution of the E‐KOB. Zircon U–Pb dating analysis suggests that the diorites were formed in the Early Ordovician at ca. 470 Ma. Furthermore, the εHf(t) values (5.3–14.1), Mg# values (39.7–51.2), and Nb/Ta (12.8–14.8), Zr/Hf (33.8–44.8), and Lu/Yb (0.15–0.16) ratios are generally close to those of depleted mantle‐derived rocks and the diorites were originated from a depleted asthenosphere mantle source. In addition, these diorites are characterized by enriched light rare earth elements (LREEs) (La and Nd) and depleted high‐field‐strength elements (HFSEs) (Nb, Ta, P, and Ti), similar to the fingerprints of arc‐related gabbroic‐dioritic rocks. This is also consistent with their high H2Omelt (6.0–8.3%) and oxygen fugacity (logfO2 = −14.3 to −13.5) features, indicating that they were formed in a subduction‐related setting. Our new investigations suggest that the Proto‐Tethys Ocean in the East Kunlun was still actively subducting northward during the Early Ordovician. [ABSTRACT FROM AUTHOR]

During the Early Permian, the Kazakhstan-Junggar Block collided with the Siberian Craton, while the Chinese Altai entered a stage of syn- to post-collision evolution. In this period, a large-scale intrusion of mantle-derived magma provided the necessary heat to initiate intense interaction between the crust and mantle, leading to the formation of the W-mineralized Bastielieke granitic pluton. [Display omitted] • The Bastielieke granitic pluton formed at 278–270 Ma in a syn- to post-collision setting. • The granitic pluton was derived from crusal recycling of sedimentary rocks. • There is a genetic link between the granitic pluton and W deposit in Bastielieke. Granitic magmatism of the Altai orogen is the key to understanding the tectonic evolution and metallogeny in the Central Asian Orogenic Belt (COAB). In this paper, we conducted comprehensive petrological, geochronological and geochemical investigations on the Bastielieke granitic pluton in the Altai orogen. Zircon U–Pb dating shows an emplacement age of 278–270 Ma for the pluton. Granites of the Bastielieke pluton have S-type granitic affinity and have Zr + Nb + Ce + Y contents (76.6–272 ppm), A/CNK ratios > 1.1, and K 2 O > Na 2 O. The low ε Nd (t) (−2.8 to + 2.9) and high ε Hf (t) (+7.6 to + 15.9) values with Nd-Hf isotope decoupling, invariable Pb isotopes, and moderate zircon δ18O V-SMOW values suggest crustal recycling of sedimentary rocks in a syn- to post-collision setting. In addition, the pluton is spatially related to the tungsten (W) deposit and also temporally consistent with the mineralization age of 284 ± 6 Ma, indicating a genetic link between the Early Permian magmatism and mineralization in Bastielieke. Furthermore, the source rocks of the pluton which are sedimentary rocks and abundant in W, provide the material basis for the initial enrichment of W in primary magmas. Given high Rb/Sr (>3) and low K/Rb ratios (<2 0 0), we interpret that the pluton has experienced high differentiation. Our studies propose that the termination of the subduction-accretion of the Paleo-Asian Ocean and the initiation of a syn- to post-collision regime for the Altai orogen are probably at the Early Permian. [ABSTRACT FROM AUTHOR]

Radiogenic isotopes of igneous and detrital minerals from various clastic rocks of mountain belts are used to reveal tectonic and sedimentary processes, which are otherwise difficult to detect. Here, we discuss the results of U–Pb and Lu–Hf zircon systems, and 40Ar/39Ar on detrital white mica in Eastern Alps. Zircon and white mica are chemically and mechanically stable and occur in magmatic, metamorphic and sedimentary rocks. During subsequent metamorphism, zircon is resistant against high temperature, >650 °C (U–Pb) and 900 °C (Lu–Hf). The Lu–Hf zircon system is used as a tracer of initial magma separation from the mantle, and the U–Pb zircon system records magmatic crystallization. The 40Ar/39Ar white mica system is stable up to 400–450 °C dating either formation or cooling after high-grade metamorphism. Detrital U–Pb zircon ages on two major rivers draining the Eastern Alps do not record any sign of Alpine orogeny or metamorphism. Consequently, U–Pb zircon studies can entirely miss the record of collisional orogeny in cool, magma-poor collision orogens. In contrast, 40Ar/39Ar white mica ages record Early and Late Alpine metamorphism but are limited to revealing the pre-orogenic history. U–Pb zircon and 40Ar/39Ar white mica yield different information in provenance studies. In the Eastern Alps, U–Pb zircon dating of magmatic and clastic rocks indicates intense formation of magmatic rocks between 630 and 230 Ma. Felsic rocks dominate the older age groups, and increasingly young mafic rocks were dated, specifically between 265 and 230 Ma. Hf isotopes record increasing juvenile input since ∼630 Ma. Two different groups with respect to Mesoproterozoic depleted mantle ages are shown: (1) one group with a Mesoproterozoic age gap typical for Gondwana-derived units, and (2) a rare group with Mesoproterozoic ages recording a new tectonic element in the Austroalpine basement in Alps. [ABSTRACT FROM AUTHOR]

The Neoproterozoic granitoids in East Kunlun Orogen (EKO) record critical information on the composition and evolution of the early crustal materials, as well as the Precambrian tectonic evolutionary history of the Qaidam Block, northern Tibetan Plateau. Zircon U–Pb geochronology and Hf isotopic compositions of three newly discriminated gneissic granitoids in the Hongshuihe, Dangennaomuru and south Bokalike areas are employed in this study to elucidate the Neoproterozoic tectonics of EKO. Petrological studies reveal that these granitoids are S–type granite with abundant Al–rich minerals like muscovite and garnet in their mineral assemblages. Zircon U–Pb geochronological results show that the Hongshuihe and Dangennaomuru plutons yield weighted mean 206 Pb/ 238 U ages of 914 ± 5 Ma (MSWD = 0.25) and 935 ± 6 Ma (MSWD = 0.56), respectively, indicating their magmatic crystallization ages. And the south Bokalike pluton yields upper and lower intercept ages of 1002 ± 31 Ma and 388 ± 39 Ma (MSWD = 0.63), disclosing its magmatic crystallization age and the time of subsequent Paleozoic metamorphic event, respectively. The ε Hf ( t ) values of zircons in this study are dominated by negative with minor positive values ranging from −7.18 to +2.76. The two–stage Hf model ages of the zircons having negative ε Hf ( t ) values are ca. 1.7–2.0 Ga, whereas those with positive ε Hf ( t ) values are ca. 1.5 Ga. Both the ε Hf ( t ) values and the two–stage Hf model ages indicate that these granitoids were probably derived from the reworking of ancient continental crustal materials with minor mantle contribution. Combined with available data of the granitoids in EKO, central and north Qaidam Block, we propose that the Neoproterozoic granitoids in Qaidam Block have similar crystallization ages of ca. 0.9–1.0 Ga, as well as same or similar geochemical and zircon Hf isotopic compositions revealing the Qaidam Block was involved into the amalgamation of the supercontinent Rodinia. [ABSTRACT FROM AUTHOR]

Abstract: LA-ICP-MS U–Pb ages of detrital zircons from clastics of the undated fore-arc sedimentary unit (FAS) along the Shangdan Suture and the Middle–Upper Devonian Liuling Group in the South Qinling belt are used to establish the maximum depositional age and provenance of these tectonic units which were deposited on both sides of the Shangdan suture zone between the North China Block (NCB) and South China Block (SCB). The new data and geological evidence show that the FAS was deposited in a fore-arc basin with an exclusive source of the clastics in the North Qinling Belt (NQB). The depositional age of FAS is limited by the youngest U–Pb 455Ma-ages of detrital zircons from clastics and the intrusive age of 435±7Ma of mafic dykes between the Late Ordovician–Early Silurian, while the NCB was still separated from the SCB by the Shangdan Ocean. However, detrital zircon U–Pb ages from six samples of the Middle Devonian Liuling Group indicate sources in both NQB and SCB suggesting pre-Middle Devonian collision of NCB and SCB. All results indicate deposition of the FAS in a forearc setting upon an active continental margin during Late Ordovician–Early Silurian, while the Middle–Upper Devonian Liuling Group represents a marine foreland basin after closure of the Shangdan Ocean. Together with the unconformity between Middle Devonian and pre-Devonian strata, this reveals still evolving subduction and accretion on the southern side of the NQB during the Ordovician-Early Silurian, and the Early Devonian collision between the NCB and SCB. [Copyright &y& Elsevier]

Abstract: The Neoproterozoic mafic intrusions and granitoids of the Hannan and Micangshan massifs, located at the northwestern margin of the Yangtze Block in South China, are composed mainly of subduction-related plutons. Here we present LA-ICPMS zircon U–Pb data on the granitoids from Wudumen, Xishenba, Xixiang and Hanshan within the Hannan massif which show crystallization ages of 718±9Ma, 706±9Ma, 707±20Ma and 777±8Ma, respectively. The arc-related Mujiaba gabbros display crystallization age of 746±4Ma. In the Micangshan massif, the crystallization ages of the granodiorite at Daheba, and the granites at Xihe and Guangwushan are 871±77Ma, 832±5Ma and 838±17Ma, respectively, whereas the Shatan diorite, Xihe and Zhengyuan gabbroic intrusions yield crystallization ages of 840±6Ma, 824±4Ma and 857±46Ma, respectively. The tonalites in the Wudumen pluton display adakitic affinity, characterized by strong depletion of Nb, Ta, P and Ti, and enrichment of large-ion lithophile elements (LILE) (i.e. Cs, Rb, Ba, Th, U and K) as well as positive Pb and Sr anomalies, suggesting an origin by the melting of a thickened mafic lower crust at ca. 718Ma. The syenogranite at Xixiang is characterized by depletion of Nb, Ta, Sr, P and Ti, and marked enrichment of LILE, K and Pb, indicating a post-collisional orogenic collapse at ca. 707Ma. The results from our study suggests that the arc-related magmatism migrated from Micangshan area during ca. 870–820Ma, through Huijunba-Xixiang in ca. 840–820Ma, and to Hannan during 825–706Ma, based on which we propose an accretionary tectonic model for the northwestern margin of the Yangtze Block. [Copyright &y& Elsevier]

[Display omitted] • Newly ca. 880 Ma gabbro-diorite and gabbro are identified in the Bikou Terrane. • Both the gabbro-diorite and gabbro were formed in a subduction-related tectonic setting. • The Bikou Terrane was a part of the subduction-related system during the early Neoproterozoic. The Neoproterozoic mafic intrusions in the Bikou Terrane along the northwestern margin of the Yangtze Block record crucial information on evaluating the tectonic evolution of the Yangtze Block, South China. However, their petrogenesis and tectonic significance are still poorly constrained. In this paper, we present the results of a comprehensive study of zircon U–Pb geochronology and whole-rock geochemistry from the gabbro-diorites and gabbros of the Bikou Terrane. Zircon U–Pb dating results indicate that these gabbro-diorite and gabbro samples were formed coevally at ca. 880 Ma. The gabbro-diorite samples are calc-alkaline in composition and have intermediate contents of SiO 2 , Mg#, Ni, and Cr. They are enriched in LREEs, and depleted in HFSEs (i.e., Nb, Ta, Zr, and Hf). They have relatively high ratios of Th/Yb, and low ratios of Nb/Yb, Nb/La, Th/Nd, Th/Zr, and U/Th, indicating that they were derived from partial melting of a mantle wedge source metasomatized by slab-derived melts. The gabbro samples are commonly classified as sub-alkaline tholeiitic rocks, and have constantly low to medium values of MgO, Mg#, Cr, and Ni, with distinct spikes at Th, U, Nb and Ta concentrations. They show an E-MORB-like enriched LREEs, low ratios of Nb/La, Ta/Yb, Th/La, and Nb/Zr, and medium ratios of Nb/Yb and Th/Yb, implying that they were most probably originated from the interaction between the upwelling enriched asthenospheric mantle and the mantle wedge peridotite. This mechanism may be triggered by the slab rollback process in a subduction-related environment. Our new investigations, along with available observations from other scholars, support the persistent subduction-related system along the northwestern margin of the Yangtze Block during the early Neoproterozoic. [ABSTRACT FROM AUTHOR]

The Qinling orogenic belt preserves the records of a long evolution history of convergence between the North China Craton and the South China Craton. In this study, we present results from new geological, geochemical, zircon U–Pb geochronological and Lu–Hf isotopic investigations on a suite of orthogneisses from the Taihua Group (THG) and Tietonggou Group (TGG). We also present geochronological data on schist and migmatite from the North Qinling belt (NQB) and metasedimentary rocks from the Wuguan unit (WGU) which is exposed along the southern side of the Shangdan suture zone. Two orthogneisses from the THG define several stages of arc magmatism at ∼2.51 Ga, ∼2.34 Ga, ∼2.28 Ga and ∼2.16 Ga, followed by metamorphism at 1930 ± 31 Ma. Zircons from the TGG trace a tectonothermal event at 1897 ± 15 Ma. Geochemical data on biotite gneiss from the THG and the TTG (tonalite–trondhjemite–granodiorite) gneiss from the TGG classify these rocks as dacite and display volcanic arc affinity. Zircon Lu–Hf isotopic results suggest that the parental magma for the protolith of felsic gneisses were derived from Mesoarchean crustal components ( T DM C = 2766–3067 Ma). The amphibole gneiss from the THG classifies as metabasalt and the zircons from this rock show dominantly negative ε Hf ( t ) values varying from −10.3 to −4.6 and T DM C range of 3088–3437 Ma, suggesting magma derivation by melting of Paleoarchean–Mesoarchean subducted oceanic crust. Zircons in the schist from the NQB show a wide age population in the range of 937–1131 Ma (peak at 1035 Ma). Zircons from the melanosomes of the migmatite in the NQB define ages between 405 and 379 Ma, correlating with the melting event in the NQB during 450–380 Ma. The WGU shows age populations of 854–803 Ma (with a peak at 829–824 Ma), ∼2460 Ma, ∼1802 Ma and 1180–1000 Ma, which are markedly different from that of the NQB and SQB. The ages obtained in our study correlate with the widely reported Grenvillian-aged magmatism in the NQB, and suggest that the NQB might have been a discrete micro-continent during Paleo- and Mesoproterozoic which has been overprinted by Paleozoic tectonic event. [ABSTRACT FROM AUTHOR]

The southern Peninsular India preserves a number of Archean cratonic nuclei among which the Coorg Block is considered to represent a Mesoarchean microcontinent. Here we investigate the southern margin of this block where remnants of rare ultramafic rocks in association with arc magmatic rocks and accreted metasediments occur in the Wynad region. We present petrology, mineral chemistry, whole rock geochemistry and zircon U–Pb and Lu–Hf data from a suite of meta ultramafics and associated diorite, orthopyroxene-bearing felsic charnockite, and quartz-mica schist. The peak P – T conditions of metamorphism of these rocks are estimated at 720–840 °C and 6.5–8.7 kbar. The geochemical features of the ultramafic suite provide evidence for melting and metasomatism of lithospheric mantle in a suprasubduction zone (SSZ) setting with the involvement of both silicate melts and slab-dehydrated fluids. The parent melts were generated at varying depth levels extending from spinel to garnet stability fields. A subduction-modified, LREE replenished, metasomatically enriched mantle source endorses arc-like chemical signatures in the melts that were acquired through interaction between the depleted sub-arc lithospheric mantle and subduction components. We report the common presence of magmatic zircons in the meta ultramafic rocks with crystallization ages of 3.3–3.0 Ga. Some of these rocks also carry another younger group of magmatic zircons with crystallization ages down to ca. 2.5 Ga. Zircons in the orthopyroxene-bearing felsic charnockite also formed at 3.2–3.0 Ga whereas those in the metadiorite crystallized at around 2.6–2.5 Ga. The detrital zircons in the quartz mica schist show upper intercept age of 3.3 Ga, and lower intercept at 2.5 Ga. The Mesoarchean ages from the Wynad suite are consistent with the ages reported from the Coorg Block, whereas the Neoarchean ages correspond with those in the Nilgiri Block to the south. The Lu–Hf data from zircon grains in the various samples show both negative and positive εHf(t) values ranging from −18.23 to 13.98. The data yield Hf depleted mantle model ages (T DM ) of 2562–3837 Ma and Hf crustal residence model ages ( T DM C ) ranging from 2576 Ma to 4009 Ma, indicating magma derivation from both juvenile and reworked components of Neohadean to early-mid Archean age. Our results reveal a suprasubduction zone mantle wedge that has been repeatedly replenished through multiple events of subduction zone magmatism in the Mesoarchean and Neoarchean. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale Upper Eocene plutons in the Western Alborz–Azarbaijan orogenic belt mostly show calc-alkaline and I-type geochemical features contrasted by the Tarom complex with its high-potassic to shoshonitic affinity. The pluton was emplaced in the Tarom subzone of the orogenic belt and its laser ICP-MS zircon U–Pb age of 41Ma is interpreted as the age of magma crystallization. The Tarom complex is composed of quartz monzodiorite, quartz-monzonite and monzogranite, the SiO2 contents range from 57 to 70wt.%, the K2O+Na2O content is high (5.0–8.9wt.%) and K2O/Na2O ratio ranges from 0.4 to 1.9. All the investigated rocks are enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs), and bear a weak Eu anomaly (Eu/Eu*=0.46 to 1.38) in chondrite-normalized trace element patterns. The samples display some variety in initial Sr and Nd isotopic compositions, marked with low ISr =0.704–0.705 and εNd (40Ma) =−4.2 to +3.4 (−5.7 for an enclave) values. The Pb isotopic ratios are (206Pb/204Pb)=18.52–18.86, (207Pb/204Pb)=15.57–15.72 and (208Pb/204Pb)=38.47–39.08. Comparison with experimental studies, together with mantle-like isotopic ratios and comparisons of REE patterns, points to an origin of chemically enriched lithospheric mantle source for the Tarom plutonic complex. Partial melting process involving different partial melting degrees affecting heterogeneously metasomatized mantle is a process that seems likely to have occurred in the studied complex as the major differentiation process. The Tarom monzonitic plutons are considered to be post-orogenic intrusions that were emplaced in an environment of lithospheric extension, causing asthenospheric upwelling. Asthenospheric upwelling induced a thermal anomaly which caused partial melting of metasomatized subcontinental lithospheric mantle in the Tarom area. [Copyright &y& Elsevier]