The Origin of Mesozoic A-type Granitoids,Fujian Province,Southeast China:Insights from Geochronology,Mineralogy and Geochemistry

The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of~101 and~98 Ma,and they have a high formation temperature(~910℃)and low oxygen fugacity value,indicating crystallization condition at low pressure in the upper crust with temperature of 678℃.The Qishan and Kuiqi miarolites are characterized by enrichment in SiO_(2) and high-K alkali,depletion in Ca and Mg,and belong to the high-K weak peraluminous rock series.The samples are enriched in HFSEs(i.e.,Ta,Zr and Hf)and LILEs(i.e.,Ba,P and Sr),depleted in Ba and Sr with the negative anomaly of Eu.In the primitive mantle normalized trace element spider diagram,the samples show a right-inclined‘seagull-type’pattern,combined the ratios of(La/Yb)_(N),10000×Al/Ga,Rb/Nb and Nb/Ta etc.,they were proved to be alkaline A-type granite.Combined the characterize of the trace elements,they were derived from clay-rich source accompanied pelite melting,and subjected to K-feldspar crystallization fractional.The values of ε_(Hf)(t)and tDM2 are distributed in the range of-2.8 to 3.3 with~1.2 Ga,and-6.0 to 4.0 with~1.2 Ga,revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks.The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust,respectively,resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European-Asian Plate.

Geochronology and Geochemistry of the Xingxingxia Triassic A-type Granites in Central Tianshan,NW China:Petrogenesis and Tectonic Implications

The Triassic granitoids in Central Tianshan play a key role in determining the petrogenesis and tectonic evolution on the southern margin of the Central Asian orogenic belt.In this study,we present SHRIMP zircon U-Pb ages,Hf isotopic and geochemical data on the Xingxingxia biotite granite,amazonite granite and granitic pegmatite in Central Tianshan,NW China.Zircon U-Pb dating yielded formation ages of 242 Ma for the biotite granite and 240 Ma for the amazonite granite.These granitoid rocks have high K_(2)O with low MgO and CaO contents.They are enriched in Nb,Ta,Hf and Y,while being depleted in Ba and Sr,showing flat HREE patterns and negative Eu anomalies.They have typical A-type granite geochemical signatures with high Ga/A_(1)(8–13)and TFeO/(TFeO+MgO)ratios,showing an A_(2) affinity for biotite granite and an A_(1) affinity for amazonite granite and granitic pegmatite.Zircon ε_(Hf)(t)values of the granitoids are 0.45–2.66,with Hf model ages of 0.99–1.17 Ga.This suggests that these A-type granites originated from partial melting of the lower crust.We propose that Xingxingxia Triassic A-type granites formed under lithospheric extension from post-orogenic to anorogenic intraplate settings and NE-trending regional strike-slip fault-controlled magma emplacement in the upper crust.

Geochronology and Geochemistry of Early Cretaceous A-type Granites in Central-Eastern Inner Mongolia,China:Implications for Late Mesozoic Tectonic Evolution of the Southern Great Xing'an Range

The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.

Vibration attenuation performance of wind turbine tower using a prestressed tuned mass damper under seismic excitation

With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cause excessive vibration of the WTT.To investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this study.First,a mathematical model is established based on structural dynamics under seismic excitation.Then,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning optimization.Next,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal acceleration.Finally,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the PTMD.In addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.

Research on Transmission Line Tower Tilting and Foundation State Monitoring Technology Based onMulti-Sensor Cooperative Detection and Correction

The transmission line tower will be affected by bad weather and artificial subsidence caused by the foundation and other factors in the power transmission.The tower’s tilt and severe deformation will cause the building to collapse.Many small changes caused the tower’s collapse,but the early staff often could not intuitively notice the changes in the tower’s state.In the current tower online monitoring system,terminal equipment often needs to replace batteries frequently due to premature exhaustion of power.According to the need for real-time measurement of power line tower,this research designed a real-time monitoring device monitoring the transmission tower attitude tilting and foundation state based on the inertial sensor,the acceleration of 3 axis inertial sensor and angular velocity raw data to pole average filtering pre-processing,and then through the complementary filtering algorithm for comprehensive calculation of tilt angle,the system meets the demand for inclined online monitoring of power line poles and towers regarding measurement accuracy,with low cost and power consumption.The optimization multi-sensor cooperative detection and correction measured tilt angle result relative accuracy can reach 1.03%,which has specific promotion and application value since the system has the advantages of unattended and efficient calculation.

Design Optimization of a Lattice Tower: Structure and Foundations

Produced in power plants, electrical energy is transported to places of consumption via the electricity network. At the heart of this network are the supports that allow electricity to be efficiently transported over long distances, guaranteeing the security and supply of energy to the various centers of use. In the construction of a line, supports occupy an important part in terms of safety and construction cost. It is therefore essential to optimize their use to reduce the cost of transmission lines. This work addresses this problem, which focuses on the optimal utilization of X-lattice towers in the construction of overhead power lines. The challenge is to reconcile the search for optimal cost and respect for the design, resistance and service constraints of the structure. To do this, a parameter having a strong correlation with the weight, foundation and construction cost of the X-lattice tower for 161 kV lines is determined as an important cost variable. This parameter is the wheelbase of the towers. The junction point between the structure and the foundations is obtained by measuring the forces at the base of the tower following the lowering of the loads. These efforts make it possible to size foundations which are of the inverted or isolated sole type. The results obtained reveal that from 8 meters in width, the wheelbase gradually changes until the optimum is obtained at 6.29 meters. With this wheelbase, the production cost is optimal. It clearly emerges from this study that the construction of lattice pylons with a wheelbase of approximately 6.29 meters makes it possible to optimize the cost of construction of 161 kV lines in the Republic of Benin.

Tower Semiconductor Acquisition: Advancing Intel’s Presence in the Global Market

This paper delves into the economic event surrounding Intel Corporation’s high-profile acquisition of Tower Corporation.It aims to investigate the reasons behind Intel’s decision to acquire Tower,employ the SWOT analysis method to evaluate the event,and examine its impact on relevant stakeholders.The findings indicate that Intel’s acquisition of Tower was driven by objectives such as strengthening business areas,expanding market share,technological innovation and development,and future development strategy.Through the application of SWOT analysis,it becomes evident that the advantages of the acquisition lie in strengthening technical capabilities and expanding business segments,while simultaneously facing challenges such as integration complexities and pressure.The significance of this paper lies in gaining a comprehensive understanding of the strategic motivations and potential impacts associated with corporate acquisitions,thereby providing valuable insights for decision-making processes.The innovation lies in the comprehensive utilization of SWOT analysis to holistically evaluate the acquisition event,enabling a thorough assessment of its various aspects.For government and policymakers,they should strength regulation of corporate takeovers to ensure fair and transparent market competition,provide support and incentives,and strength cooperation to develop common policies and norms.As for enterprises,it is advised that strategic planning and comprehensive consideration should be formulated and carried out when making acquisitions.Also,stakeholders should actively participate in and monitor the process of corporate acquisition discussion and decision-making,and strengthen cooperation to ensure fair competition,maximizing the interests of all parties.

Evaluation of Driver-Induced Human Errors in Smart Construction Tower Crane Operations Based on DEMATEL-ISM-MICMAC

With the advent of Industry 4.0, smart construction sites have seen significant development in China. However, accidents involving digitized tower cranes continue to be a persistent issue. Among the contributing factors, human unsafe behavior stands out as a primary cause for these incidents. This study aims to assess the human reliability of tower crane operations on smart construction sites. To proactively enhance safety measures, the research employs text mining techniques (TF-IDF-Truncated SVD-Complement NB) to identify patterns of human errors among tower crane operators. Building upon the SHEL model, the study categorizes behavioral factors affecting human reliability in the man-machine interface, leading to the establishment of the Performance Shaping Factors (PSFs) system. Furthermore, the research constructs an error impact indicator system for the intelligent construction site tower crane operator interface. Using the DEMATEL method, it analyzes the significance of various factors influencing human errors in tower crane operations. Additionally, the ISM-MICMAC method is applied to unveil the hierarchical relationships and driving-dependent connections among these influencing factors. The findings indicate that personal state, operating procedures, and physical environment directly impact human errors, while personal capability, technological environment, and one fundamental organizational management factor contribute indirectly. .

Geochronological and Geochemical Constrains on Petrogenesis of the Jietebutiao A-type Granite in West Junggar,Xinjiang

Late Paleozoic post-collisional granitoids are widespread in West Junggar, as well as northern Xinjiang. As a representative of those intrusions, the Jietebutiao granite occurs in the southwestern margin of the West Junggar （northwest China）, and is mainly composed of mid-coarse- grained monzogranite and syenogranite. In the present study, we report the results of high-precision zircon laser-ablation-inductively-coupled plasma mass-spectrometry U-Pb dating on the Jietebutiao granite for the first time, and yield weighted mean 2~~pb/23SU ages of 287 ＋ 9 Ma and 278 ~ 3 Ma for monzogranite and syenogranite, respectively. The Jietebutiao granite has a pronounced A-type affinity; it is metaluminous to slightly peraluminous; has a high-K calc-alkaline composition; high concentrations of Na20 ＋ I（20, varying from 6.8 to 8.5 wt%; high FeOt/MgO; 10 000Ga/AI ratios, a low CaO, MgO, and TiO2 content; enriched in some large ion lithophile elements （LILE, such as Rb and Th） and high field strength elements （HFSE, such as Zr, Hf, and Y）; and depleted in Sr, Ba, and Ti. In addition, the granite has a relatively high rare earth element （REE） content （except for Eu）, with significant negative Eu anomalies （Eu/Eu＊ = 0.01-0.72）, and showing slight tetrad REE patterns and non-charge and radius controlled （CHARAC） trace element behavior. Petrographic, geochemical, and geochronological data suggest that the parental magma of Jietebutiao intrusions are of mixed origin, and are most probably formed by the interaction between the lower crust- and mantle-derived magmas in the Early Permian post-collisional tectonic setting. The basaltic magmas underplated and interacted with the lower crust that was dominated by deeply buried arc （and back-arc basin） series and the oceanic crust formed in the Paleozoic, and then triggered the partial melting of the juvenile lower crust, producing voluminous granitic melts and forming the Jietebutiao A2-type monzogranites, with the lithospheric mantle progressively thinning and rifting to form Al-type granites, such as syenogranites, in the Jietebutiao pluton. This further proves the important contribution of Late Paleozoic granitic magmatism in terms of vertical crustal growth in northern Xinjiang.

Age and geochemistry of Early Ordovician A-type granites in the Northeastern Songnen Block,NE China

Early Ordovician A-type granites in the northeastern(NE) Songnen Block NE China were studied to better understand the geodynamic settings in this region.This research presents new zircon U–Pb ages and wholerock geochemical data for the Early Ordovician granites in the NE Songnen Block. Zircon U–Pb dating indicates that the granite in the Cuibei, Hongxing, and Meixi areas in the NE Songnen Block formed in the Early Ordovician with ages of 471–479 Ma. The granites show geochemical characteristics of high SiO2 and K2 O compositions and low FeOT, MgO, CaO, and P2 O5 compositions. They belong to a high K calc-alkaline series and display a weak peraluminous featurPe with A/CNK values of 0.98–1.14. The rocks have aREE composition of 249.98–423.94 ppm,and are enriched in LREE with(La/Yb)Nvalues of2.87–9.87, and display obvious Eu anomalies(d Eu =0.01–0.29). Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm,and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr +Y + Nb+Ce values(324–795 ppm) and Ga/Al ratios consistent with A-type granites. Based on particular geochemical features, such as high Rb/Nb(7.98–24.19) and Y/Nb(1.07–3.43), the studied A-type granites can be further classified as an A2-type subgroup. This research indicates that the Early Ordovician A-type granites were formed by the partial melting of ancient crust in an extensional setting. Lower Sr/Y and(Ho/Yb)Nratios indicate that plagioclase and amphibole are residual in the source, and garnet is absent, implying that the magma was generated at low levels of pressure. By contrast, the contemporaneous granites in the SE Xing'an Block suggest a subduction-related tectonic setting, and its adakitic property indicates a thickened continental crust.We suggest that the Paleo-Asian Ocean plate between the Xing'an and Songnen blocks subducted northward during the Early Ordovician. Meanwhile, the NE Songnen Block was exposed to a passive continental margin tectonic setting.

The Geochemical and Zircon Trace Elements Characteristics of A-type Granitoids in Boziguoer, Baicheng County, Xinjiang

The Boziguoer A-type granitoids in Baicheng County,Xinjiang,belong to the northern margin of the Tarim platform as well as the neighboring EW-oriented alkaline intrusive rocks.The rocks comprise an aegirine or arfvedsonite quartz alkali feldspar syenite,an aegirine or arfvedsonite alkali feldspar granite,and a biotite alkali feldspar syenite.The major rock-forming minerals are albite,K-feldspar,quartz,arfvedsonite,aegirine,and siderophyllite.The accessory minerals are mainly zircon,pyrochlore,thorite,fluorite,monazite,bastnaesite,xenotime,and astrophyllite.The chemical composition of the alkaline granitoids show that SiO2 varies from 64.55％ to 72.29％ with a mean value of 67.32％,Na2O＋K2O is high （9.85％-11.87％） with a mean of 11.14％,K2O is 2.39％-5.47％ （mean =4.73％）,the K2O/Na2O ratios are 0.31-0.96,Al2O3 ranges from 12.58％ to 15.44％,and total FeOT is between 2.35％ and 5.65％.CaO,MgO,MnO,and TiO2 are low.The REE content is high and the total SREE is （263-1219） ppm （mean =776 ppm）,showing LREE enrichment and HREE depletion with strong negative Eu anomalies.In addition,the chondrite-normalized REE patterns of the alkaline granitoids belong to the ＂seagull＂ pattern of the right-type.The Zr content is （113-1246） ppm （mean =594 ppm）,Zr＋Nb＋Ce＋Y is between （478-2203） ppm with a mean of 1362 ppm.Furthermore,the alkaline granitoids have high HFSE （Ga,Nb,Ta,Zr,and Hf） content and low LILE （Ba,K,and Sr） content.The Nb/Ta ratio varies from 7.23 to 32.59 （mean =16.59） and the Zr/Hf ratio is 16.69-58.04 （mean =36.80）.The zircons are depleted in LREE and enriched in HREE.The chondrite-normalized REE patterns of the zircons are of the ＂seagull＂ pattern of the left-inclined type with strong negative Eu anomaly and without a Ce anomaly.The Boziguoer A-type granitoids share similar features with A1-type granites.The average temperature of the granitic magma was estimated at 832-839℃.The Boziguoer A-type granitoids show crust-mantle mixing and may have formed in an anorogenic intraplate tectonic setting under high-temperature,anhydrous,and low oxygen fugacity conditions.

An Early Cretaceous garnet-bearing metaluminous A-type granite intrusion in the East Qinling Orogen,central China:Petrological,mineralogical and geochemical constraints

The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen. The granite contains almost 99 vol.% felsic minerals with accessory garnet, muscovite, biotite, zircon, and Fe-Ti oxide. Garnet is the dominant accessory mineral, shows zoned texture, and is rich in w（FeO） （14.13%--16.09%） and w（MnO） （24.21%--27.44%）. The rocks have high SiO2, alkalis, FeOt/ MgO, TiO2/MgO and low A1203, CaO with w（Na2O）/w（K20）〉 ]. Their Rb, Ga, Ta, Nb, Y, and Yb contents are high and Sr, Ba, Eu, Zr, P, and Ti contents are low. These features indicate that the Erlang- miao granite is a highly evolved metaluminous A-type. Garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The relatively high initial 878r/S6Sr ratios （0.706--0.708）, low and negative εNd （120 Ma） values （-6.6 to -9.0）, and old Nd model ages （1.5--1.7 Ga） suggest that the rocks were probably formed by partial melting of the Paleoproterozoic granitic gneisses from the basement, with participation of depleted mantle in an extensional setting.

Petrogenesis and Mineralization of Two-Stage A-Type Granites in Jiuyishan,South China:Constraints from Whole-rock Geochemistry, Mineral Composition and Zircon U-Pb-Hf Isotopes

The Jiuyishan complex massif,located in the northern section of the Nanling region,is a combination of five plutons,namely,the Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan plutons.Whole-rock geochemistry,Imineral electron microprobe analysis,zircon U-Pb dating and Hf isotope analysis were carried out for the Jinjiling and Pangxiemu plutons.The zircon U-Pb dating yields weighted mean ages of 152.9±0.9 Ma for the Jinjiling pluton and 151.7±1.5 Ma for the Pangxiemu pluton,with a narrow gap between them.The Jinjiling and Pangxiemu plutons both have geochemical characteristics of high SiO2,Al2 O3,Na2 O,K2 O and low TiO2,MgO,CaO,P2 O5 contents,with intense depletions in Sr,Ba,Ti,Eu and enrichments in Ga,FeoOT and HFSE,and these characteristics reflect an A-type affinity.From the Jinjiling to the Pangxiemu plutons,the mineral composition of mica changes from lepidomelane to zinnwaldite,with increases in F,Li2 O and Rb2 O contents.The mineral composition of zircon changes from low Zr/Hf to high Zr/Hf,with increasing HfO2,P2 O5 and UO2+ThO2+Y2 O3 contents.The mineral compositions of feldspar indicate that the Pangxiemu pluton contains more alkali feldspar than the Jinjiling pluton.The whole-rock geochemistry and mineral compositions reveal a higher degree of differentiation for the Pangxiemu pluton.The nearly uniformεHf(t)indicates the same source region for the two plutons:both were derived from partial melting of the lower crust,with small contributions of mantle materials.In addition,higher F,lower Nb/Ta and Zr/Hf ratios in the Pangxiemu Pluton suggest a closer relationship with the rare metal mineralization than for the Jinjiling pluton.

Geochronology and Geochemistry of the Early Permian A-Type Granite in the Hongol Area, Central Inner Mongolia:Petrogenesis and Tectonic Implications

We performed geochronological and geochemical analyses of the A-type granite in the Hongol area, central Inner Mongolia, to determine its age, petrogenesis and tectonic setting, which are significant for clarifying the Late Paleozoic tectonic evolution of the Xing’an Mongolian Orogenic Belt(XMOB). The rock type of the A-type granite in the Hongol area is alkali-feldspar granite, and it constitutes a western part of the Baiyinwula-Dongujimqin A-type granite belt. Zircon U-Pb geochronology yieldsPb/U ages ranging from 293 to 286 Ma for the alkali-feldspar granite, indicating this granitic pluton formed in the Early Permian. The alkali-feldspar granite is high in silica(SiO=75.13 wt%-80.17 wt%), aluminum(AlO=10.59 wt%-13.17 wt%) and alkali(NaO+KO=7.33 wt%-9.11 wt%), and low in MgO(0.08 wt%-0.39 wt%) and CaO(0.19 wt%-0.70 wt%). It is obviously enriched in LILEs such as Rb, Th and K,depleted in HFSEs such as Nb, Ti, La and Ce, with pronounced negative anomalies of Nb, Ti, P, Eu, Sr and Ba. Its Sr-Nd-Pb isotopic compositions show positive ε(t)(+0.72-+3.08), low T(805-997 Ma),and high radioactive Pb with(Pb/Pb)of 18.710-19.304,(Pb/Pb)of 15.557-15.604 and(Pb/Pb)of 37.887-38.330. Petrological characteristics and geochemical data suggest that the alkalifeldspar granite in the Hongol area belongs to aluminous A-type granite. This A-type granite formed in a post-collisional extensional setting and was generated by the partial melting of felsic rocks in the middlelower crust resulting from post-collisional slab breakoff. It is suggested that the Paleo-Asian Ocean was closed before the Permian in central Inner Mongolia.

Origin of trondhjemite and albitite at the expense of A-type granite,Aravalli orogen, India:Evidence from new metasomatic replacement fronts

The A-type Harsora-Dadikar granites in the Alwar complex of northern Aravalli orogen,NW India provide evidence for subsolidus-requilibration of feldspars.They record three new discrete stages of albitisation,producing trondhjemite and albitite sequentially at the expense of original granite.Stage-I metasomatism deanorthised the magmatic oligoclase and transformed the grey least-albitised granite to pinkish grey microcline-oligoclase granite.Stage-II converted the latter to trondhjemite by replacement of microcline to oligoclase.Stage-III metasomatism led to the formation of albitite/albite granite from trondhjemite,where the metasomatically formed oligoclase was replaced by albite.This stage of metasomatism resulted in nearly complete disappearance of amphibole and biotite,producing a monomineralic rock (albitite),which is consistent with Korzhinskii theory of infiltration metasomatism.The reaction fronts delineating the Stage-II and Stage-III are sharp and easily discernible by their prominent color differences in Harsora on the outcrop scale.Chemically,the mineral transformations during three stages are manifested by the differential gains/losses in Na,K,Ca,Rb,Ba,Sr,Fe and Mg.The formation of albite,Cl-rich marialitic scapolite and Cl-rich amphibole in the albitised granites are suggestive of Naand Cl-brines as the metasomatising fluids.The fluid-rock interactions,which can significantly transform the pristine mineralogy of granitoids,should be carefully considered to avoid any misinterpretations about their petrological history.

Petrogenesis and Tectonic Implications of A-type Granites in Zhaheba in the East Junggar Region of Xinjiang,China:Evidence from Geochronology,Geochemistry and Sr-Nd Isotopic Compositions

The magma source,petrogenesis,tectonic setting and geochronology of the late Paleozoic A-type granites widely exposed in the Zhaheba area,East Junggar,have thus far not been well-constrained.A better understanding of these issues will help to reveal the magmatic processes and continental growth of Central Asia.The A-type granites in Zhaheba include the Ashutasi alkaline granites and the Yuyitasi syenogranites,which were emplaced at 321.5±4.8 Ma and 321.7±0.6 Ma,respectively.The major rock-forming minerals are orthoclase,perthite,arfvedsonite and quartz,which exhibit the following principal geochemical characteristics of A2-type granites.(1)Their REE distribution curves each exhibit a‘V’-shaped pattern and a marked depletion in Eu.They are rich in large-ion lithophile elements Rb,Th and U as well as high-field-strength elements Nb,Ta,Zr and Hf,but significantly depleted in Ba,Sr,P and Ti.(2)Their(^(87)Sr/^(86)Sr)i values(0.7021-0.7041),εNd(t)values(4.57-5.16)and REE distribution patterns are in basic agreement with those of the Kalamaili A-type granite belt in East Junggar.The T DM2 values of the alkaline granites and syenogranites range from 661 to 709 Ma.The A-type granites may be the products of upwelling asthenosphere-triggered partial melting of immature lower crust.The alkaline granites were late-stage products of crystallization and differentiation.Compared to the syenogranites,the alkaline granites are significantly lower in K_(2)O,Na_(2)O,Al_(2)O 3,FeO,MgO and CaO,but significantly higher in incompatible elements(e.g.,SiO_(2),Rb,and Sr).The magmatic crystallization temperatures of the syenogranites and alkaline granites are 874℃ and 819℃,respectively.As their age gradually decreases(peak ages:322 Ma and 307 Ma,respectively),there is a gradual decrease in the T_(DM2)of the A-type granites and a gradual increase in theεNd(t)value from the Ulungur belt to the Kalamaili belt in East Junggar.The study of A-type granites is therefore one of the keys to understanding the laws and mechanisms of crustal accretion during the Phanerozoic period,as well as also being of great significance for understanding the Paleozoic accretion.

Petrogenesis of the Early Cretaceous Tiantangshan A-type Granite in northwestern Guangdong province, SE China and tectonic implications

1 Introduction During the late Mesozoic times,the SE China is characterized by extensive magmatism and mineralization.The widely distributed granitoids with different(I-,S-and A-)types have been inferred to be closely related to the large-scale polymetallic mineralization.The Nanling tungsten-tin polymetallic belt is endowed with considerable

Stenian A-type granitoids in the Namaqua-Natal Belt,southern Africa,Maud Belt,Antarctica and Nampula Terrane,Mozambique:Rodinia and Gondwana amalgamation implications

We carried out SHRIMP zircon U-Pb dating on A-type granitic intrusions from the Namaqua-Natal Province,South Africa,Sverdrupfjella,western Dronning Maud Land,Antarctica and the Nampula Province of northern Mozambique.Zircon grains in these granitic rocks are typically elongated and oscillatory zoned,suggesting magmatic origins.Zircons from the granitoid intrusions analyzed in this study suggest^1025-1100 Ma ages,which confirm widespread Mesoproterozoic A-type granitic magmatism in the Namaqua-Natal(South Africa),Maud(Antarctica)and Mozambique metamorphic terrains.No older inherited(e.g.,~2500 Ma Achean basement or^1200 Ma island are magmatism in northern Natal)zircon grains were seen.Four plutons from the Natal Belt(Mvoti Pluton,Glendale Pluton,Kwalembe Pluton,Ntimbankulu Pluton)display 1050-1040 Ma ages,whereas the Nthlimbitwa Pluton in northern Natal indicates older 1090-1080 Ma ages.A sample from Sverdrupfjella,Antarctica has^1091 Ma old zircons along with^530 Ma metamorphic rims.Similarly,four samples analysed from the Nampula Province of Mozambique suggest crystallization ages of^1060-1090 Ma but also show significant discordance with two samples showing younger^550 Ma overgrowths.None of the Natal samples show any younger overgrowths.A single sample from southwestern Namaqualand yielded an age of^1033 Ma.Currently available chronological data suggest magmatism took place in the Namaqua-Natal-MaudMozambique(NNMM)belt between^1025 Ma and^1100 Ma with two broad phases between^1060-1020 Ma and 1100-1070 Ma respectively,with peaks at between^1030-1040 Ma and^1070-1090 Ma.The age data from the granitic intrusions from Namaqualand.combined with those from Natal,Antarctica and Mozambique suggest a crude spatial-age relationship with the older>1070 Ma ages being largely restricted close to the eastern and western margins of the Kalahari Craton in northern Natal,Mozambique.Namaqualand and WDML Antarctica whereas the younger<1060 Ma ages dominate in southern Natal and western Namaqualand and are largely restricted to the southern and possibly the western margins of the Kalahari Craton.The older ages of magmatism partially overlap with or are marginally younger than the intracratonic Mkondo Large lgneous Provinee intruded into or extruded onto the Kalahari Craton,suggesting a tectonic relationship with the Maud Belt.Similar ages from granitic augen gneisses in Sri Lanka suggest a continuous belt stretching from Namaqualand to Sri Lanka in a reconstituted Gondwana,formed during the terminal stages of amalgamation of Rodinia and predating the East African Orogen.This contiguity contributes to defining the extent of Rodinia-age crustal blocks,subsequently fragmented by the dispersal of Rodinia and Gondwana.

The~1.4 GaA-type granitoids in the“Chottanagpur crustal block”(India),and its relocation from Columbia to Rodinia?

In paleogeographic reconstructions of the Columbia and Rodinia Supercontinents,the position of the Greater India landmass is ambiguous.This,coupled with a limited understanding of the tectonic evolution of the mobile belts along which the mosaic of crustal domains in India accreted,impedes precise correlation among the dispersed crustal fragments in supercontinent reconstructions.Using structural,metamorphic phase equilibria,chronological and geochemical investigations,this study aims to reconstruct the tectonic evolution of the Chottanagpur Gneiss Complex(CGC)as a distinct crustal block at the eastern end of the Greater Indian Proterozoic Fold Belt(GIPFOB)along which the North India Block(NIB)and the South India Block(SIB)accreted.The study focuses on two issues,e.g.dating the Early Neoproterozoic(0.92 Ga)accretion of the CGC with the NIB contemporaneous with the assembly of Rodinia,and documenting the widespread(>24,000 km^(2))plutonism of1.5-1.4 Ga weakly peraluminous,calc-alkalic to alkali-calcic and ferroan A-type granitoids(±garnet)devoid of mafic microgrannular enclaves and coeval mafic emplacements in the crustal block.These dominantly within-plate granitoids arguably formed by asthenospheric upwelling induced partial melting of garnetbearing anatectic quartzofeldspathic gneisses that dominate the Early Mesoproterozoic basement of the block.The major and trace element chemistry of the granitoids is similar to the 1.35-1.45 Ga A-type granitoids in Laurentia/Amazonia emplaced contemporaneous with the 1.5-1.3 Ga breakup of the Columbia Supercontinent.This study suggests the Chottanagpur Gneiss Complex occured as a fragmented crustal block following the breakup of the Columbia Supercontinent;the crustal block was subsequently integrated within India during the Early Neoproterozoic oblique accretion between the NIB and SIB contemporaneous with the Rodinia Supercontinent assembly.

The Silurian A-Type Granites in Northeastern Guangxi,South China Block:New Evidence of Transition from Compression to Post-orogenic Extension of the Kwangsian Orogen

Objective More and more evidence suggests that the Kwangsian orogen is probably an intraplate orogen, which is one of the few examples of intraplate orogenesis worldwide. However, the initiation time, size and scope of the Kwangsian orogeny have not been determined yet. This study analyzed the Silurian A-type granites in northeastern Guangxi, South China Block, which may provide new evidence for the transition from compression to post- orogenic extension of the Kwangsian orogen.