Peraluminous A-type granites formed through synchronous fractionation,magma mixing,mingling,and undercooling:evidence from microgranular enclaves and host Mesoproterozoic Kanigiri granite pluton,Nellore Schist Belt,southeast India

The field and microstructural features coupled with mineral chemical data from microgranular enclave(ME)and host Mesoproterozoic Kanigiri granite(KG)pluton of Nellore Schist Belt(NSB),Southeastern India,have been documented in order to infer the likely processes responsible for the origin and evolution of ME and host KG magma.The ME and host KG bear the same mineral assemblages barring the KG which does not contain amphibole;however,they are modally disequilibrated.The ME in KG is originated due to multiple intrusions of ME magmas into the crystallizing host KG magma chamber.Field and textural features indicate the dynamic magma flow,mingling,and undercooling of the ME against a relatively cooler surface of host KG magma.The presence of NSB country rock xenoliths and its diffuse boundaries suggest the intrusive relation and marginal assimilation by the intruding KG magma.The occasional cumulate texture in the ME appears to have formed by the accumulation of early-formed minerals that crystallized rapidly in the ME magma globules.The ME shows the magmatically deform features developed due to the flowage and erosion by the subsequent intrusions of ME magma pulses into the crystallizing host KG magma chamber.The ME amphiboles show unusual composition as ferro-edenitic hornblende to potassian-hastingsitic hornblende,that crystallized in the subalkaline-alkaline transition,low fO_(2)(reducing to mildly oxidizing)magma.The unusual extremely low Mg/Mg+Fe^(t)=0.015(avg.)of ME amphiboles may be related to the changing physico-chemical(P,T,fO_(2),and H_(2)O)condition of the ME magma or they might have crystallized in equilibrium with more evolved KG magma.The KG(FeOt/MgO=37.04,avg.)and ME(FeO~t/MgO=77.72,avg.)biotites are siderophyllite,and buffered between QFM and NNO syn-crystallizing in the water undersaturated(H_(2O)≈3.58 wt.%in KG;≈3.53wt.%in ME),alkaline anorogenic(A-type)host magmas that were emplaced at mid-crustal(4–5 kbar;17 km)depth.Field,microtextural and mineral chemical evidences suggest that the alkaline KG magma originated from crustal source and evolved through synchronous fractionation,mixing,and mingling with coeval ME magmas in the KG magma chamber.

Geochemical Orientation Study of Stream Sediment Samples in the Southern Part of Nuggihalli Schist Belt: Ore Mineral Phases and Their Implications on the Bedrock Potential for Ores

Stream sediment sampling is a significant tool in geochemical exploration. The stream sediment composition reflects the bedrock geology, overburden cover, and metalliferous mineralization. This research article focuses on assessing selected trace element concentrations in stream sediments and interpreting their inter-element relationships using multivariate statistical methods. Tagadur Ranganathaswamy Gudda and its surroundings in the Nuggihalli schist belt of southern India have been investigated in the present work. The geology of the study area is complex, with a diverse range of litho units and evidence of strong structural deformation. The area is known for its mineralization potential for chromite, vanadiferous titanomagnetite, and sulfides. The topography of the region is characterized by an undulating terrain with a radial drainage pattern. Most part of the schist belt is soil covered except the Tagadur Ranganathaswamy Gudda area. For this study, a discrete stream sediment sampling method was adopted to collect the samples. Stream sediment samples were collected using a discrete sampling method and analyzed for trace elements using an ICP-AES spectrophotometer: Fe, Cr, Ti, V, Cu, Ni, Zn, Pb, Mn, Cd, and As have been analyzed. The analytical data were statistically treated using the SPSS software, including descriptive statistics, normalization of data using natural log transformation, and factor analysis with varimax rotation. The transformed data showed a log-normal distribution, indicating the presence of geochemical anomalies. The results of the study provide valuable insights into the geochemical processes and mineralization potential of the study area. The statistical analysis helps in understanding the inter-element relationships and identifying element groups and their implications on bedrock potential mineralization. Additionally, spatial analysis using inverse distance weighting interpolation provides information about the distribution of geochemical parameters across the study area. Overall, this research contributes to the understanding of stream sediment geochemistry and its application in mineral exploration. The findings have implications for future exploration efforts and can aid in the identification of potential ore deposits in the Nuggihalli schist belt and similar geological settings.

Dynamic response characteristics of dry and watersaturated schist under impact loading

Many geological engineering hazards are closely related to the dynamic mechanical properties of rock materials.However,most existing studies on the dynamic mechanical properties of rock materials were conducted on the hard rocks such as sandstone,granite,limestone,and marble,whereas soft rocks,such as schist,are less studied.Therefore,in this study,a series of triaxial impact tests were conducted on dry and saturated schist by employing a modified triaxial split Hopkinson pressure bar system to reveal the coupling effects of water,strain rate,and triaxial confining pressure on the mechanical properties of schist.The results show that schist is a type of watersensitive rock and the stress-strain curve of saturated schist has apparent ductility.The effects of strain rate on dynamic strain,deformation modulus and peak stress were analyzed.The results also show that the dynamic peak stress is affected by the combined softening effect and viscous effect of water under impact loading.Finally,it was found that the failure mode of schist belongs to typical axial tensile failure under uniaxial impact tests,and shear failure is the main failure mode under triaxial impact tests.With the increase in confining pressure,the failure modes of schist change from tensile failure to shear failure.This research can provide useful parameters for geological engineering hazard prevention in mountain areas.

Trace Elemental Expression in Soil Substratum and Floral Species in Selected Lateritic Profiles in the Northern Part of Kolar Schist Belt, Dharwar Craton, India

Extensive laterite cappings are observed in the northern part of Kolar schist belt and they are underlain by pillowed metabasalt and partially weathered auriferous cherty intercalations. To appraise the possible distribution of trace elements in both laterite cappings and in plants growing over there, a geobotanical study was conducted in the well exposed, almost flat to slightly undulating lateritic profiles in Jaderi-Holur-Nayakarahalli stretch in the northern part of Kolar schist belt. Due to humus-poor lateritic soil and scanty rainfall, the vegetation is sparse and scrubby. Shrub species are relatively more abundant than herbs and trees. The shrub species studied are Argyreia cuneata, Dodonaea viscosa, Carissa carandas, Ziziphus species, Barleria buxifolia and Atylosia scarbiocides. The herb species are mainly represented by Leucas ciliata, Pulicaria wightiana, Hyptis suaveolens, Tephrosia tinctoria, Trichodesma indicum, Stylosanthes fruticosa, Evolvulus alsinoides, Pavonia zeylanica, Orthosiphon diffusus, Waltheria indica and Stachytarpheta indica. Less frequent species included Acacia megaladena and Dolichandrone atrovirens. Geochemical analysis of different plant species and lateritic soil samples has been carried out. Cu, Cr, Zn, Ni, Co, As, Mn and Mg are in good concentration in soil but the same are impoverished in the plant species except Mn. A few analyses for Au show that its values are close to background concentration. However, plant uptake of Au appears to be better (25 - 86 ppb). The humic acid activity could have enabled gold to get absorbed by plants. While all other analyzed metals show higher range of concentration in soil compared to flora, gold shows a reverse relationship.

Shear-Controlled Gold Mineralization of G. R. Halli Area of Chitradurga Schist Belt, Dharwar Craton: Insights from Fluid Inclusion Study

Gold mineralization at G. R. Halli is located along the Central shear zone of Chitradurga schist belt, extending from west of Gonur, through east of G. R. Halli and C. K. Halli to east of Honnemardi, roughly parallel to stratigraphic units. The NNW-SSE trending shear zone has a width of 0.5 to 1.5 km shows extensive carbonatization of metabasalts and the associated lithologies confined to NNW-WNW trending arcuate brittle-ductile zone. The sheared and silicified contact zones between carbonaceous argillite and schistose metabasalt form the potential sites for localization of mineralization. The gold is associated with sulphides mainly pyrite, arsenopyrite, galena, sphalerite, minor chalcopyrite. Textural relationship indicates two stage sulphide mineral assemblages co-relatable with two stage fluid ascents having temperature of homogenization between 125°C and 256°C. It is a typical epigenetic lode gold system, which got affected by later deformation.

Petrological Characteristics of the Peddavura Schist Belt and Adjacent Rocks in Eastern Dharwar Craton in Parts of Nalgonda District, Telangana State

The Peddavura greenstone Linear Belt, NW-SE trending, is formed in the Eastern part of the Dharwar Craton of south India, extended over 62.5 sq•km in Nalgonda and Guntur districts region. The entire belt is illustrated as Peninsular Gneiss. The Belt Study has attracted geologists for conducting further research to evaluate the crust forming process at the time of early volcanic eruption of Earth’s history. The South Indian Dharwar Craton depicts and exposes the crustal segments where geological activities took place consistently during the Precambrian. The PSB (Peddavura Schist Belt) mostly consists of meta volcanic (meta basalts), amphibolites, granites, dolerites, basaltic andesites, pegmatite and Banded Magnetite Quartzite’s (BMQ) rock types. The 20 represented rock samples made for thin section studies. Based on the Petrological studies minerals are showing uralitization, saussuritization in the granite with mylonite structures, perthite and dolerite are showing heavy metal such as rutile and other opaque minerals (Magnetite, hematite, and typical pyrite crystal) are present in different represented rock samples. The minerals are showing different alteration zones along with microstructures. Using the Petrological studies the minerals and rock types are identified in the study region.

Comparative Geochemical and Petrographic Studies of the Various Granitoids between Central and Western Arm, in the Central Part of Ramagiri Schist Belt and Their Petrogenetic Histories

Granitoids between the central and western arm of Ramagiri schist belt in its central part, are broadly classified into the migmatite gneiss, grey granodiorite and pink monzogranite, based on field characteristics and petrographic features. These granitoids belong to the Tonalite-Granodiorite-Monzogranite (TGM) suite of PGC-II. All the samples are fresh as per the CIA values, PC1-PC2 binary plot and MFW ternary plot. The granodiorites occupy the expected field in the normative IUGS, TAS, and R1-R2 classification diagrams, but the monzogranites occupy the monzogranite field in the normative IUGS classification diagram and granite to alkali granite field in the rest. The granodiorites exhibit both ferroan to magnesian, alkali-calcic nature with metaluminous I type features and falls in the calc-alkaline to high K calc-alkaline series. They have high ΣREE (an average 327.905 ppm) content, and show LREE enrichment ((La/Sm)N = 3.1 - 6.8) with enriched but relatively flat HREE ((Gd/Yb)N = 1.75 - 5.26) patterns and weak negative to positive Eu anomaly (Eu/Eu* = 0.62 - 1.18). The monzogranites, on the other hand, are peraluminous, alkalic, ferroan, high K calc-alkaline, S-type granites, exhibiting relatively low ΣREE (an average 118.693 ppm) contents, strongly fractionated REE patterns with highly enriched LREE ((La/Sm)N =1.74 - 9.76), depleted HREE ((Gd/Yb)N = 0.43 - 2.21) patterns having concave upward shape, and strong negative Eu anomaly (Eu/Eu* = 0.23 - 0.89). Geothermobarometry revealed the average emplacement temperature and pressure of the granodiorites and monzogranites as 812.5℃, 8.14 ± 0.6 kbar and 775℃, 3.14 kbar, respectively. Based, on the observations, it can be concluded that the granodiorites have formed in volcanic arc setting by partial melting of the lower crust and S-type monzogranites have been produced at a relatively shallower depth in the crust, by continental crust recycling due to hydrothermal influx.

New Data on the Mineralogy of Chromite from the Nuggihalli Schist Belt,Western Dharwar Craton,Karnataka,India:Petrogenetic Implications

在使变形的分层的火的建筑群的铬铁矿和主人 serpentinites 的有韵律的 layering 的出现在西方的 Dharwar craton 在 Nuggihalli 片岩带(NSB ) 被注意了， Karnataka，南方印度。为这研究， chromitite 岩石样品在 NSB 从 Jambur， Tagadur， Bhakatarhalli， Ranganbetta 和 Byrapur 被收集。岩相学和矿石铬铁矿上的显微镜的研究显示出强烈 cataclasis 和改变到 ferritchromite。ferritchromite 作文被更高的 Cr 数字描绘(Cr/[Cr+Al ])(0.680.98 ) 并且更低的 Mg 数字(Mg/[Mg+Fe ])(0.330.82 ) 在与父母铬铁矿的相比的 ferritchromite 的比率。为 ferritchromite 的形成过程被认为与在铬铁矿之间的 Mg，艾尔， Cr，和 Fe 的交换有关，包围硅酸盐(serpentines，绿泥石) ，并且液体在 serpentinization 期间。

Correlations between ultrasonic pulse wave velocities and rock properties of quartz-mica schist

Physico-mechanical properties are critically important parameters for rocks. This study aims to examine some of the rock properties of quartz-mica schist(QMS) rocks in a cost-effective manner by establishing correlations between non-destructive and destructive tests. Using simple regression analysis, good correlations were obtained between the pulse wave velocities and the properties of QMS rocks. The results were further improved by using multiple regression analysis as compared to those obtained by the simple linear regression analysis. The results were also compared to the ones obtained by other empirical equations available. The general equations encompassing all types of rocks did not give reliable results of rock properties and showed large relative errors, ranging from 23% to 1146%. It is suggested that empirical correlations must be investigated separately for different types of rocks. The general empirical equations should not be used for the design and planning purposes before they are verified at least on one rock sample from the project site, as they may contain large unacceptable errors.

Geochemistry of Late Archaean shaly BIF formed by oxic exogenic processes: an example from Ramagiri schist belt,Dharwar Craton, India

The central block of the auriferous Ramagiri schist belt, in the Eastern Dharwar Craton, India consists of bimodal volcanics(mafic-felsic), shaly BIF and metasedimentary rocks. Geochemical studies of the associated shaly BIF have indicated the enrichment of the major and trace elements such as Si O2, Al2O3, Ti O2, K2 O, Mg O, Fe2O3(T),Zr, Y, Cr, Ni, alkali and alkaline earth elements indicates that the clastic component of the shaly BIF had their contribution from the contemporaneous bimodal volcanics.The concave chondrite normalized REE patterns share ubiquitously anomalous positive cerium anomaly, absence of positive europium anomaly and the overall HREE enrichment. The REE patterns resemble those from the modern day sea water, except for positive Ce anomaly. The data suggests that arc related bimodal volcanism had been the plausible source of Fe, silica, REE and other trace elements. The coherent behaviour of Fe, Ti, Mn and P with the REEs indicates that they got incorporated from Fe–Ti–Mn bearing primary minerals and secondary products like clays. The variability of REE patterns in the BIF formation samples probably results from the differences in scavenging efficiency. The BIF bears signatures of mixing of the contemporaneous clastic and chemical processes, as well as the changes accompanying diagenesis and metamorphism.The precipitation of Fe did not stop during the sedimentation in an island arc related tectonic setting. The BIF strongly lacks the signatures from hydrothermal input. The presence of positive cerium anomalies and the absence of positive europium anomalies in the shaly banded ironformations imply that iron oxidation during BIF deposition took place in shallow waters rather than at depth, at oxicanoxic boundary.

Tectonic Setting of the Kadiri Schist Belt, Andhra Pradesh, India

Plate tectonic activity has played a critical role in the development of petrotectonic associations in the Kadiri schist belt. The calc alkaline association of basalt, andesite, dacite and rhyolite(BADR) is the signature volcanic rock suite of the convergent margin. The N-S belt has gone below the unconformity plane of Cuddapah sediments. In the northern part geochemical and structural attributes of the Kadiri greenstone belt is studied along with microscopic observations of selected samples. Harker diagram plots of major elements generally indicate a liquid line of descent from a common source, such that BADR rocks are derived from a common parent magma of basaltic to andesitic composition. These calc-alkaline volcanic rocks are formed at convergent margins where more silicic rocks represent more highly fractionated melt. All the litho-units of this greenstone belt indicate crush and strain effects. The stretched pebbles in the deformed volcanic matrix with tectonite development along with associated greenschist facies metamorphism, alteration and hydration is remarkable. Flow foliation plane with N-S strike and very low angle(5° to 10°) easterly dip and N-S axial planar schistosity formed due to later phase isoclinal folding can be clearly identified in the field. Basic intrusives are quite common in the surrounding area. All the observations including the field setting and geochemistry clearly demonstrate ocean-continent subduction as the tectonic environment of the study area.

循环加卸载下黑云母石英片岩的弹性模量与能量演化特征研究

黑云母石英片岩是一种典型的各向异性岩石,为研究其损伤演化规律及各向异性表现特征,针对含0°,45°,90°3种片理角度的试样,开展了等塑性应变循环加卸载试验。结果表明:不同片理面角度试样的破坏模式有所不同,0°片理面试样中的张拉破裂现象与45°片理面中的剪切破坏现象尤为明显。随着塑性应变增加,黑云母石英片岩的弹性模量表现出先强化、后弱化的现象,这一现象在高围压下更为明显。在弱化阶段中,弹性模量演化的转折点与裂纹起裂强度σci稳定时对应塑性应变一致。弹性模量作为岩石损伤劣化过程的评价指标较完整性系数受片理面角度的影响更小。在岩石内部能量演化过程中,耗散能大小与片理面角度的关系为0°>90°>45°,耗散能、弹性能下降的速率大小关系为45°>90°>0°,其降至稳定时与岩石损伤强度σcd稳定时对应塑性应变一致。该研究借助弹性模量和能量演化规律分析,探究了黑云母石英片岩的损伤演化力学行为。

大姚县秀水河铜金矿成矿地质条件及找矿前景探讨

大姚县秀水河铜金矿矿体主要赋存于花岗质片麻岩、糜棱岩化白云英片岩中,受构造破碎带控制,岩石劈理、节理裂隙发育,较破碎,具硅化、碳酸盐化等特征,矿化主要为铜矿化及褐铁矿化,见孔雀石、褐铁矿呈细脉状、薄膜状、浸染状沿破碎带分布,局部可见少量黄铜矿、蓝铜矿、斑铜矿呈散点状分布。通过区内土壤地球化学测量工作,发现区内元素组合异常与已知矿化带吻合较好,异常浓集中心与已知矿点相对应,且异常强度高,指示该区具有良好的成矿地质条件及较大的找矿前景。

Electrical Conductivity of Eclogite, Amphibolite and Garnet-Quartz-Mica Schist with Implications for the Conductivity in the Qiangtang Terrane of Northern Tibetan Plateau

Understanding the electrical conductivity of high pressure metamorphic rocks is essential to constrain the compositions in the subduction zone and continental crust. In this study, we calculated the electrical conductivity for such rocks sampled from the central Qiangtang metamorphic belt in the northern Tibetan Plateau. The results reveal that, when aqueous fluids are absent, the conductivity of meta-mafic rocks(e.g., eclogite and amphibolite) is strikingly higher than that of meta-felsic rocks(e.g., garnet-quartz-mica schist). The conductivity of eclogite decreases due to the enrichment of amphibole, but this effect is diminished when a critical degree of amphibolization is reached. Our calculated conductivity of eclogite and amphibolite differs greatly from the experimentally derived results for the eclogites from other localities, partly owing to the strong effects of different mineral assemblages and chemical compositions on the conduction mechanisms and efficiencies. However, the disparity of conductivity between our calculated and the previously measured results for a similar amphibole-rich eclogite sampled from the same locality suggests that trails of highly conductive rutile-ilmenite aggregates may contribute to the higher bulk-rock conductivity in the laboratory measurements. Moreover, since the calculated conductivity of eclogite and amphibolite is not high enough at the temperatures relevant to their metamorphic thermal condition, partial melts or aqueous fluids originated from the upwelling asthenosphere are more likely to explain the anomalously high electrical conductivity zones in magnetotelluric images in the Qiangtang terrane in the northern Tibetan Plateau.

The white schist assemblage in the kyanite quartzite from the ultrahigh-pressure metamorphic belt, eastern Dabie Mountains

The kyanite quartzite from the ultrahigh-pressure metamorphic belt in the eastern Dabie Mountains is composed mainly of quartz, kyanite, talc and epidote, which contains a typical mineral assemblage of white schist. It suffered an eclogite facies metamorphism of P =(2 4±0 3) GPa and T =630℃ together with coexisting eclogite. The protolith may be an aplite replaced by high-pressure fluid of eclogite facies.

CLFD-TS协同固化云母片岩强风化土性能试验研究

为解决云母片岩强度低等难题,提出采用以水泥-石灰-粉煤灰-脱硫石膏为材料的新型粉体固化剂(Cement-Lime-Fly ash-Desulfurized gypsum,CLFD),协同尾矿渣(Tailings Slag,TS)物理改良作用加固路基土。通过开展室内力学试验,研究了不同固化剂掺量和不同养护龄期下固化土的力学与耐久性能,结合X射线衍射分析与扫描电镜试验揭示固化土的强度形成机理。结果表明:CLFD-TS固化土试样的力学性能、水稳性能、抗干湿循环性能都有了显著的改善,浸水9 d后固化剂掺入比不低于6%时,承载比与回弹模量均可满足规范要求;微观测试表明固化土中存在C-S-H、C-A-H凝胶及AFt、CaSO_(4)晶体,这些产物通过胶结填充土颗粒,提高了土体的强度和密实度,增强土体性能;CLFD-TS固化土的早期强度主要来源于尾矿渣的物理骨架级配改良和水泥组分的水化作用,后期强度则由固化剂的火山灰作用提供。最后,建立了CLFD-TS协同固化土的微观作用机制模型,可为类似研究提供理论依据。

内蒙古中西部宝音图群云母片岩的变质P-T轨迹与锆石年代学研究

位于内蒙古中西部地区的宝音图群,主要由云母片岩、斜长角闪岩、石英岩和大理岩等组成。其中云母片岩中发育典型的巴罗式递增变质带,目前对于该递增变质带的研究非常薄弱。本文对宝音图群的云母片岩开展了系统的岩相学、矿物化学、相平衡模拟以及锆石U-Pb年代学的研究。岩相学研究结果显示,三个云母片岩样品具有不同的峰期矿物组合,分别为石榴子石+白云母+黑云母+斜长石+石英,十字石+白云母+黑云母+斜长石+钛铁矿+石英,石榴子石+蓝晶石+白云母+黑云母+斜长石+钛铁矿+石英。此外,样品LS93和LS07存在晚期红柱石的叠加。相平衡模拟研究限定三个云母片岩的峰期温度压力分别为:577℃、0.73 GPa,620℃、0.78 GPa和670℃、0.8 GPa,具有递增型特征,其峰期温度压力指示的地热梯度为18~20℃/km,为典型的中压相系;此外,三个样品的P-T轨迹均显示早期升温升压直至峰期阶段,随后降温降压的顺时针型,反映地壳加厚和后期抬升的演化过程。云母片岩中的锆石发育典型的变质边结构,变质边的Th/U=0.004~0.02,锆石U-Pb年代学结果显示该变质年龄为398±6 Ma,代表峰期或近峰期阶段的变质年龄。综合分析认为,宝音图群巴罗式变质带可能形成于与古亚洲洋闭合有关的碰撞造山背景。

辽宁弓长岭鞍山群时代与物源--来自石榴十字云母片岩碎屑锆石U-Pb-Hf同位素特征与稀土元素组成的约束

鞍山群是华北克拉通东部陆块最重要的含BIF变质表壳岩之一,经历了绿片岩相—角闪岩相变质-变形作用,准确限定其沉积时代与物质来源,对于探究华北克拉通BIF的构造环境具有重要意义。利用LA-MC-ICP-MS(多接收激光剥蚀电感耦合等离子质谱仪)对弓长岭鞍山群石榴十字云母石英片岩进行了碎屑锆石U-Pb-Hf同位素与稀土元素原位分析。根据碎屑锆石阴极发光图像特征与U-Pb年龄结果,获得石榴十字云母石英片岩中最年轻一组碎屑锆石峰值年龄为2528 Ma,限定了其原岩的最大沉积时代,结合区内约2500 Ma齐大山富钾花岗岩侵入鞍山群的野外地质关系,以及鞍山群经历了2510~2470 Ma变质作用,认为弓长岭地区鞍山群沉积时代为2528~2510 Ma,属于新太古代晚期。鞍山群十字石榴云母石英片岩碎屑锆石年龄集中在2931~2454 Ma之间,最主要的峰值年龄为2528 Ma。结合碎屑锆石内部结构特征,认为鞍山群主要物源为新太古代晚期酸性岩浆岩。代表性碎屑锆石Hf两阶段模式年龄为3532~2711 Ma,峰值年龄为2830 Ma,进一步揭示了中太古代晚期是鞍山—本溪地区地壳最重要的生长阶段。综合鞍山—本溪地区已发表的相关地球化学数据,推测弓长岭鞍山群可能沉积于活动大陆边缘的弧后盆地。

含铜石榴黑云片岩动态力学特性及损伤本构模型

为探究深部矿岩在不同加载条件下的动态力学特性及损伤规律,以深部回采的含铜石榴黑云片岩为对象,开展6种轴压σ_(ap)(0 MPa、6 MPa、12 MPa、18 MPa、24 MPa、30 MPa)、6种围压σ_(p)(0 MPa、4 MPa、8 MPa、12 MPa、16 MPa、20 MPa)及6种冲击速度v(18.68 m/s、20.9 m/s、23.54 m/s、26.63 m/s、29.26 m/s、31.95 m/s)条件下的动静组合冲击试验,并考虑冲击速度、轴压、围压及应变率因素,基于统计损伤理论和Drucker-Prager破坏准则建立动静组合加载下含铜石榴黑云片岩的动态损伤本构模型。研究结果表明:矿岩试件的应力-应变曲线几乎无压密阶段,当应力增加至峰值应力的65%~80%时,该阶段的应力-应变曲线出现阶跃现象;不同埋深矿岩的受力状态和冲击速度显著影响了深部围岩的动态破坏模式,当σ_(p)=12 MPa、v=31.95 m/s时,随着轴压σ_(ap)的增加,动态抗压强度先增加、后降低,而峰值应变线性递减,当σ_(p)=12 MPa、σ_(ap)=24 MPa时,动态抗压强度随应变率的增大线性增加,而峰值应变随应变率的增加呈二次多项式增长;模型理论曲线与试验曲线吻合度均较高,验证了该动态本构模型的可靠性,可为深埋岩体动态本构模型研究及工程应用提供一定的参考。

绢云母石英片岩浮选尾砂提纯工艺研究

本研究利用绢云母石英片岩浮选云母后获得的石英尾砂为原料提纯制备了纯度99.9%高纯石英粉。研究结果表明,采用熔解-中和-灼烧提纯工艺,可打破SiO_(2)晶格内化学键,可使石英晶格中采用物理法提纯无法去除的气液包裹体类和类质同象类等杂质转移到熔液中,再通过固液分离使其得以有效去除而获得高纯石英粉。