Magma Mixing Genesis of the Mafic Enclaves and Related Granitoids in the Kan Granite-Gneiss Complex of Central Côte d’Ivoire: Evidence from Geology, Petrology and Geochemistry

The mafic enclaves from Paleoproterozoic domain are considered to be the results of large-scale crust-mantle interaction and magma mixing. In this paper, petrography, mineralogy and geochemistry were jointly used to determine the origin of the mafic enclaves and their relationship with the host granitoids of the Kan granite-gneiss complex. This study also provides new information on crust-mantle interactions. The mafic enclaves of the Kan vary in shape and size and have intermediate chemical compositions. The diagrams used show a number of similarities in the major elements (and often in the trace elements) between the mafic enclaves and the host granitoids. Geochemical show that the Kan rock are metaluminous, enriched in silica, medium to high-K calc-alkaline I-type granite. The similarities reflect a mixing of basic and acid magma. Mafic enclaves have a typical magmatic structure, which is characterized by magma mixing. The genesis of these rocks is associated with the context of subduction. They result from the mixing of a mafic magma originating from the mantle and linked to subduction, and a granitic magma (type I granite) that arises from the partial melting of the crust.

Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata

In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality.

Mineral Chemistry,Trace Elements,Isotopic Analysis and Zircon U-Pb Dating in the Hesar Pluton,Northern UDMA,Iran:Implications for Pre-Collisional Magma Mixing

The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.

Petrology,geochemistry,and crystal size distribution of the basaltic andesite-dacite association at Mt.Sumbing,Central Java,Indonesia:Insights to magma reservoir dynamics and petrogenesis

Ten rock samples consisting of one pyroclastic density current(PDC1)deposit,seven lava flows(LF1–7),and two summit lava domes(LD1,2)were studied to understand the petrogenesis and magma dynamics at Mt.Sumbing.The stratigraphy is arranged as LF1,PDC1,LF2,LF3,LF4,LF5,LF6,LF7,LD1,and LD2;furthermore,these rocks were divided into two types.TypeⅠ,observed in the oldest(LF1)sample,has poor MgO and high Ba/Nb,Th/Yb and Sr.The remaining samples(PDC1–LD2)represent typeⅡ,characterized by high MgO and low Ba/Nb,Th/Yb and Sr values.We suggest that type I is derived from AOC(altered oceanic crust)-rich melts that underwent significant crustal assimilation,while typeⅡoriginates from mantle-rich melts with less significant crustal assimilation.The early stage of typeⅡmagma(PDC1–LF3)was considered a closed system,evolving basaltic andesite into andesite(55.0–60.2 wt%SiO_(2))with a progressively increasing phenocryst(0.30–0.48φ_(PC))and decreasing crystal size distribution(CSD)slope(from-3.9 to-2.9).The evidence of fluctuating silica and phenocryst contents(between 55.9–59.7 wt%and 0.25–0.41φ_(PC),respectively),coupled with the kinked and steep(from-5.0 to-3.3)CSD curves imply the interchanging condition between open(i.e.,magma mixing)and closed magmatic systems during the middle stage(LF4–LF6).Finally,it underwent to closed system again during the final stage(LF7–LD2)because the magma reached dacitic composition(at most 68.9 wt%SiO_(2))with abundant phenocryst(0.38–0.45φ_(PC))and gentle CSD slope(from-4.1 to-1.2).

The Applicability and Productiveness of a Systematic Literature Review Methodology in Volcanology Research: Case of the Magma Pathway at the Mount Cameroon Volcano

The presented research illustrates the applicability and productiveness of the systematic literature review methodology, a non-empirical methodology in the geological sciences, particularly volcanology. The systematic literature review methodology is a replicable, rigorous, and transparent methodology for synthesizing existing literature to answer questions on a specific topic. The synthesis allows for knowledge consolidation, such as identifying knowledge gaps. In our illustration of this methodology, we focused on the expanding knowledge about the magma pathway at Mount Cameroon, one of Africa’s active volcanoes. Our synthesis of the relevant international geoscience research literature is based on the framework of knowledge about the magma pathway beneath a typical basaltic volcano. The framework has three primary components: magma supply, storage, and transport to erupting vents. Across these components is a total of twelve secondary components. The result is a previously non-existent and fragmented overall understanding of the magma pathway at Mount Cameroon. The gaps in the understanding (such as in the magma supply rates, timescales of chamber processes, and magma ascent rates) may be addressed in future research. Another key implication of the presented research lies in the proof of concept of the systematic literature review methodology as an applicable qualitative research methodology in the study of volcanoes.

Source Enrichment Control on the Scale of Magmatic-Hydrothermal W-Sn Mineralization:Insights from Triassic and Jurassic Magma Reservoirs in the Continental Crust,Xitian,South China

There are two factors,source composition and magmatic differentiation,potentially controlling W-Sn mineralization.Which one is more important is widely debated and may need to be determined for each individual deposit.The Xitian granite batholith located in South China is a natural laboratory for investigating the above problem.It consists essentially of two separate components,formed in the Triassic at ca.226 Ma and Jurassic at ca.152 Ma,respectively.The Triassic and Jurassic rocks are both composed of porphyritic and fine-grained phases.The latter resulted from highlydifferentiated porphyritic ones but they have similar textural characteristics and mineral assemblages,indicating that they reached a similar degree of crystal fractionation.Although both fine-grained phases are highly differentiated with elevated rare metal contents,economic W–Sn mineralization is rare in the Triassic granitoids and this can be attributed to less fertile source materials than their Jurassic counterparts,with a slightly more enriched isotopic signature and whole-rockεNd(226 Ma)of−10.4 to−9.2(2σ=0.2)compared withεNd(152 Ma)of−9.2 to−8.2(2σ=0.2)for the Jurassic rocks.The initial W-Sn enrichment was derived from the metasedimentary rocks and strongly enhanced by reworking of the continental crust,culminating in the Jurassic.

In situ U-Pb dating and trace elements of magmatic rutile from Mujicun Cu-Mo deposit,North China Craton:Insights into porphyry mineralization

Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generated within intra-continental settings.Although previous studies have focused on the age,origin and ore genesis of the Mujicun deposit,the ore-forming age,magma source and tectonic evolution remain controversial.Here,this study targeted rutile(TiO_(2))in the ore-hosting diorite porphyry from the Mujicun Cu-Mo deposit to conduct in situ U-Pb dating and trace element composition studies,with major views to determine the timing and magma evolution and to provide new insights into porphyry Cu-Mo metallogeny.Rutile trace element data show flat-like REE patterns characterized by relatively enrichment LREEs and depleted HREEs,which could be identified as magmatic rutile.Rutile U-Pb dating yields lower intercept ages of 139.3–138.4 Ma,interpreted as post magmatic cooling timing below about 500℃,which are consistent or slightly postdate with the published zircon U-Pb ages of diorite porphyry(144.1–141.7 Ma)and skarn(146.2 Ma;139.9 Ma)as well as the molybdenite Re-Os ages of molybdenum ores(144.8–140.0 Ma).Given that the overlap between the closure temperature of rutile U-Pb system and ore-forming temperature of the Mujicun deposit,this study suggests that the ore-forming ages of the Mujicun deposit can be constrained at 139.3–138.4 Ma,with temporal links to the late large-scale granitic magmatism at 138–126 Ma in the Taihang Orogen.Based on the Mg and Al contents in rutile,the magma of ore-hosting diorite porphyry was suggested to be derived from crust-mantle mixing components.In conjunction with previous studies in Taihang Orogen,this study proposes that the far-field effect and the rollback of the subducting Paleo-Pacific slab triggered lithospheric extension,asthenosphere upwelling,crust-mantle interaction and thermo-mechanical erosion,which jointly facilitated the formation of dioritic magmas during the Early Cretaceous.Subsequently,the dioritic magmas carrying crust-mantle mixing metallic materials were emplaced and precipitated at shallow positions along NNE-trending ore-controlling faults,eventually resulting in the formation of the Mujicun Cu-Mo deposit within an intracontinental extensional setting.

基于MAGMA软件的支架铸造工艺优化

以EMD大功率内燃机车支架为例,应用MAGMA模拟软件,采用温度场模拟分析和凝固补缩模拟分析,优化了铸钢件铸造工艺.根据优化后的铸造工艺方案,进行了试生产,通过解剖分析、鉴定,未发现缩孔缺陷,验证了铸造方案的可行性.采用计算机模拟浇注取代传统的试生产后验证的方法,降低了新产品的试制成本,缩短了试制周期.

基于MAGMA的球铁齿轮箱铸造工艺设计

针对球铁齿轮箱,进行了铸造工艺设计,并利用MAGMA分析软件进行了流动场、凝固场分析验证,成功地实现了该产品的批量生产,为同类产品的工艺设计提供了参考依据。

基于MAGMA的球墨铸铁铸造工艺裕度分析

基于MAGMA的模拟计算,研究40 mm×200 mm×100 mm试块在不同浇注温度、砂型刚度、孕育和石墨析出的条件下缩松行为。模拟研究表明:石墨析出率和孕育效果变化对铸件缩松形成有明显影响,浇注温度变化对铸件缩松的形成影响较小,即石墨析出和孕育方式的工艺裕度小,浇注温度的工艺裕度较大,这与试验结果基本一致;MAGMA对砂型刚度对铸件缩松形成影响的模拟结果与试验不符。

基于Magma的高压铸造模具温度场模拟分析

以汽车变速箱体零件为模型,运用Magma软件。模拟变速箱体在铸造过程中的充型流态,并对模具进行温度场模拟,分析定模、动模在喷涂前后的温度场状况。通过多组的工艺参数组合模拟,最后得到较好的模拟状态。由生产试验得知,在模具实时温度控制中,参数化调节是困难的。通过先行在Magma中模拟缩小工艺参数区间,将模拟的参数复制到压铸机上,通过微调得到理想模具温度,解决产品压铸的品质问题。能有效降低产品报废率,提高设备综合效率。

MAGMA软件辅助分析解决金属型薄壁铝合金壳体厚大部位的缩松缺陷

使用MAGMA软件对薄壁铝合金壳体低压砂芯金属型铸造的凝固过程进行模拟分析,发现通过在铸件局部厚大部位对应的金属型位置上设置紫铜镶块,同时在紫铜镶块与金属型间设置排气通道,可有效加强厚大部位的冷却速度和排气效果,减少薄壁铸件局部厚大部位产生缩松缺陷的可能性。

基于MAGMA的发动机缸体铸造工艺优化

发动机缸体作为汽车的核心部件之一,其质量优劣直接决定了汽油机的性能和工作寿命。为了提高发动机缸体性能,对NT型发动机缸体的铸造工艺进行设计,并采用MAGMA模拟软件对初步设计工艺进行模拟优化。在此过程中,通过MAGMA软件重点研究了缸体在铸造过程中的充型性、液相残余和缺陷分布,分析了充型不平稳以及缺陷产生的原因,随后以此作为重要依据,优化设计了铸件的浇冒口系统。经模拟验证,该优化工艺能够解决铸件液态成型时存在的问题,最终确定了合理的发动机缸体铸造工艺参数。

基于MAGMA的地铁电机端盖铸造工艺优化设计

在电机端盖的生产过程中,铸件的厚大部位存在铸造缺陷。为消除此缺陷,使用MAGMAsoft凝固模拟软件对初始工艺进行了分析和优化,解决了铸件的缩松问题,最终得到了合格的铸件。

基于MAGMA软件的大马力主轴承盖的工艺优化

利用MAGMA软件对主轴承盖3种工艺方案的充型和凝固过程的温度场、流场以及缩孔缩松进行模拟,通过对模拟结果的对比分析,优选出合理的工艺方案并进行优化。采用优化的工艺方案进行生产,成功生产了主轴承盖铸件,避免了多个方案在实际生产中更改工艺、反复调试造成交期延后和成本浪费,从而有效提高了新产品开发的一次成功率。

基于MAGMAsoft的连接支架铸铝件铸造工艺设计

采用solidwork三维造型软件,利用MAGMAsoft模拟软件,对连接支架铸铝件铸造生产过程进行CAE模拟。经过多次模拟,选择了最适合的浇注系统和冒口设计,以及冷铁加载方位,可以有效地改善热节状态,达到消除和控制缺陷的目的,使铸件能够达到质量要求。

大地的雕刻——解读西班牙Magma艺术和会议中心

Magma艺术和会议中心是西班牙建筑师费尔兰多·费尼斯(Fernando Menis)的代表作。文章以建筑的造型、空间和建构为切入点,解读该建筑与环境景观的关系。"大地的雕刻"是其对环境景观特征的呼应和强化。

为模拟混合设计提供最佳平台——访微捷码(Magma)公司董事长主席兼首席执行官瑞杰夫·曼德哈温

前不久，一场叫做MUSIC（Magma Users Summit on Integrated Circuits）的IC行业会议在上海召开，这是由EDA厂商Magma公司举办的集成电路用户高峰会。这场每年一届的年度盛会被誉为是“工程师思想交流的论坛”，来自全国各地的IC设计工程师近200人出席。会上，记者就Magma公司的产品、技术以及EDA领域的热点问题采访了该公司董事长主席兼首席执行官瑞杰夫·曼德哈温。

Timing of Magma Mixing in the Gangdisê Magmatic Belt during the India-Asia Collision: Zircon SHRIMP U-Pb Dating

Abundant mafic microgranular enclaves (MMEs) extensively distribute in granitoids in the Gangdise giant magmatic belt, within which the Qüxü batholith is the most typical MME-bearing pluton. Systematic sampling for granodioritic host rock, mafic microgranular enclaves and gabbro nearby at two locations in the Qüxü batholith, and subsequent zircon SHRIMP II U-Pb dating have been conducted. Two sets of isotopic ages for granodioritic host rock, mafic microgranular enclaves and gabbro are 50.4±1.3 Ma, 51.2±1.1 Ma, 47.0±l Ma and 49.3±1.7 Ma, 48.9±1.1 Ma, 49.9±1.7 Ma, respectively. It thus rules out the possibilities of mafic microgranular enclaves being refractory residues after partial melting of magma source region, or being xenoliths of country rocks or later intrusions.Therefore, it is believed that the three types of rocks mentioned above likely formed in the same magmatic event, i.e., they formed by magma mixing in the Eocene (c. 50 Ma). Compositionally, granitoid host rocks incline towards acidic end member involved in magma mixing, gabbros are akin to basic end member and mafic microgranular enclaves are the incompletely mixed basic magma clots trapped in acidic magma. The isotopic dating also suggested that huge-scale magma mixing in the Gangdise belt took place 15-20 million years after the initiation of the India-Asia continental collision, genetically related to the underplating of subduction-collision-induced basic magma at the base of the continental crust. Underplating and magma mixing were likely the main process of mass-energy exchange between the mantle and the crust during the continental collision, and greatly contributed to the accretion of the continental crust, the evolution of the lithosphere and related mineralization beneath the portion of the Tibetan Plateau to the north of the collision zone.

MAGMA在芯盒模具设计中的应用

随着铸件质量要求越来越高,对砂芯的质量也提出了更高的要求。本文以某气缸体水套砂芯的芯盒模具设计为例,介绍了MAGMA软件的制芯模块在芯盒模具设计中的应用。结果表明,模具设计效率和准确性得到提高,利用该模具制造出来的砂芯饱满紧实,质量好。