Статті в журналах: "Slab melt"

1

Wei, Bowen, Tao Jiang, Shiju Li, Youyun Zhang, Guangming Xu, Yong Li, and Zhaodong Wang. "Improving element uniformity and mechanical properties of Al–Mg–Si alloy fabricated by twin roll casting with superheat melt treatment." Materials Research Express 9, no. 1 (January 1, 2022): 016516. http://dx.doi.org/10.1088/2053-1591/ac4a2c.

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Abstract The effect of superheat melt treatment(SMT) on microstructure and properties of Al–Mg–Si alloy fabricated by twin roll casting(TRC) was analyzed using optical microscope, scanning electron microscopy, emission electron probe micro analyzer and transmission electron microscopy. SMT increased the subcooling degree of melt during TRC. The solidification microstructure with high dendrite density and small dendrite spacing was obtained. The second phase was evenly distributed between dendrites and the solute concentration gradient was decreased. Intergranular solute aggregation caused by Reynolds’ dilatancy in TRC slab was effectively suppressed. The homogeneous solute distribution of TRC slab with SMT can be realized by short-time homogenization heat treatment. The size of insoluble particles was greatly reduced. The complete decomposition of non-equilibrium eutectic phase increased the solute concentration in α-Al, which promoted the precipitation of precipitates during aging heat treatment. The tensile strength and yield strength of T6 slab were improved, while the uniform elongation are almost not decreased. The strength and uniform of slab in T4P state were both improved. The obtained results can help further shorten the production cycle of TRC slabs and improve mechanical properties.

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2

Nishitsuji, Yohei, Elmer Ruigrok, Martín Gomez, Kees Wapenaar, and Deyan Draganov. "Reflection imaging of aseismic zones of the Nazca slab by global-phase seismic interferometry." Interpretation 4, no. 3 (August 1, 2016): SJ1—SJ16. http://dx.doi.org/10.1190/int-2015-0225.1.

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Obtaining detailed images of aseismic parts of subducting slabs remains a large challenge for understanding slab dynamics. Hypocenter mapping cannot be used for the purpose due to the absence of seismicity, whereas the use of receiver functions might be compromised by the presence of melt. Global tomography can be used to identify the presence of the slab, but it does not reveal the structure in detail. We have determined how detailed images can be obtained using global-phase seismic interferometry. The method provides high-resolution ([Formula: see text] in depth) pseudo zero-offset (i.e., colocated source and receiver) reflection information. We have applied the method to aseismic zones of the Nazca slab in which initiation of possible slab tearing and plume decapitation was identified by global tomography and electrical conductivity, respectively. We have obtained an image of the Moho and the mantle and found an attenuated area in the image consistent with the presence of an aseismic dipping subducting slab. However, our interpretation was not unambiguous. The results confirmed that the method is useful for imaging aseismic transects of slabs.

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3

Samoilovich, Yu A. "Melt circulation in thin solidifying steel slab." Steel in Translation 40, no. 3 (March 2010): 256–60. http://dx.doi.org/10.3103/s0967091210030149.

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4

Sakai, Hideki. "How does a slab-shaped solid melt?" Surface Science 348, no. 3 (March 1996): 387–92. http://dx.doi.org/10.1016/0039-6028(96)01033-3.

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5

Liu, Jiachao, Jie Li, Rostislav Hrubiak, and Jesse S. Smith. "Origins of ultralow velocity zones through slab-derived metallic melt." Proceedings of the National Academy of Sciences 113, no. 20 (May 3, 2016): 5547–51. http://dx.doi.org/10.1073/pnas.1519540113.

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Understanding the ultralow velocity zones (ULVZs) places constraints on the chemical composition and thermal structure of deep Earth and provides critical information on the dynamics of large-scale mantle convection, but their origin has remained enigmatic for decades. Recent studies suggest that metallic iron and carbon are produced in subducted slabs when they sink beyond a depth of 250 km. Here we show that the eutectic melting curve of the iron−carbon system crosses the current geotherm near Earth’s core−mantle boundary, suggesting that dense metallic melt may form in the lowermost mantle. If concentrated into isolated patches, such melt could produce the seismically observed density and velocity features of ULVZs. Depending on the wetting behavior of the metallic melt, the resultant ULVZs may be short-lived domains that are replenished or regenerated through subduction, or long-lasting regions containing both metallic and silicate melts. Slab-derived metallic melt may produce another type of ULVZ that escapes core sequestration by reacting with the mantle to form iron-rich postbridgmanite or ferropericlase. The hypotheses connect peculiar features near Earth's core−mantle boundary to subduction of the oceanic lithosphere through the deep carbon cycle.

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6

Samoilovich, Yu A. "Melt circulation in a thin solidifying steel slab." Steel in Translation 40, no. 1 (January 2010): 4–8. http://dx.doi.org/10.3103/s096709121001002x.

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7

Zhao, Zhi Hao, Jian Zhong Cui, Qing Feng Zhu, and Gao Song Wang. "Experimental and Numerical Study of the Influence of a Low-Frequency Electromagnetic Field on the As-Cast Structure of Horizontal Direct Chill Casting Aluminum Alloy Slab." Advanced Materials Research 79-82 (August 2009): 1265–68. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1265.

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The influences of low frequency electromagnetic field on the as-cast structure of horizontal direct chill casting aluminum alloy slab were experimental and numerical studied. The results of numerical analysis show that the interaction of the low-frequency electromagnetic field and the melt can generate an electromagnetically induced forced flow in the melt, which, in turn, changes flow pattern and temperature field in the mold. the as-cast structure of slab can be greatly improved by the changes of flow pattern and temperature field. The results of experimental analysis show that the grains of low frequency electromagnetic casting (LFEC) are fine, uniform, equiaxed, rosette-shaped; the surface of the slab of LFEC has no cold shut and less exudations. Moreover, the low-frequency electromagnetic field can improve the distribution of solute elements in the slab. The macrosegregation such as negative segregation and gravity segregation were reduced, which results in the homogenous distributions of the solute elements over the cross-section of the slab.

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8

Drummond, M. S., M. J. Defant, and P. K. Kepezhinskas. "Petrogenesis of slab-derived trondhjemite–tonalite–dacite/adakite magmas." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 87, no. 1-2 (1996): 205–15. http://dx.doi.org/10.1017/s0263593300006611.

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ABSTRACT:The prospect of partial melting of the subducted oceanic crust to produce arc magmatism has been debated for over 30 years. Debate has centred on the physical conditions of slab melting and the lack of a definitive, unambiguous geochemical signature and petrogenetic process. Experimental partial melting data for basalt over a wide range of pressures (1–32 kbar) and temperatures (700–1150°C) have shown that melt compositions are primarily trondhjemite–tonalite–dacite (TTD). High-Al (> 15% Al2O3 at the 70% SiO2 level) TTD melts are produced by high-pressure (≥ 5 kbar) partial melting of basalt, leaving a restite assemblage of garnet + clinopyroxene ± hornblende. A specific Cenozoic high-Al TTD (adakite) contains lower Y, Yb and Sc and higher Sr, Sr/Y, La/Yb and.Zr/Sm relative to other TTD types and is interpreted to represent a slab melt under garnet amphibolite to eclogite conditions. High-Al TTD with an adakite-like geochemical character is prevalent in the Archean as the result of a higher geotherm that facilitated slab melting. Cenozoic adakite localities are commonly associated with the subduction of young (<25 Ma), hot oceanic crust, which may provide a slab geotherm (≍9–10°C km−1) conducive for slab dehydration melting. Viable alternative or supporting tectonic effects that may enhance slab melting include highly oblique convergence and resultant high shear stresses and incipient subduction into a pristine hot mantle wedge. The minimum P–T conditions for slab melting are interpreted to be 22–26 kbar (75–85 km depth) and 750–800°C. This P–T regime is framed by the hornblende dehydration, 10°C/km, and wet basalt melting curves and coincides with numerous potential slab dehydration reactions, such as tremolite, biotite + quartz, serpentine, talc, Mg-chloritoid, paragonite, clinohumite and talc + phengite. Involvement of overthickened (>50 km) lower continental crust either via direct partial melting or as a contaminant in typical mantle wedge-derived arc magmas has been presented as an alternative to slab melting. However, the intermediate to felsic volcanic and plutonic rocks that involve the lower crust are more highly potassic, enriched in large ion lithophile elements and elevated in Sr isotopic values relative to Cenozoic adakites. Slab-derived adakites, on the other hand, ascend into and react with the mantle wedge and become progressively enriched in MgO, Cr and Ni while retaining their slab melt geochemical signature. Our studies in northern Kamchatka, Russia provide an excellent case example for adakite-mantle interaction and a rare glimpse of trapped slab melt veinlets in Na-metasomatised mantle xenoliths.

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9

Xu, Lin, Qun-Wu Pei, Ze-Feng Han, Shuo Yang, Jian-Yu Wang, and Yan-Tao Yao. "Modeling Study on Melt Flow, Heat Transfer, and Inclusion Motion in the Funnel-shaped Molds for Two Thin-Slab Casters." Processes 10, no. 12 (December 19, 2022): 2738. http://dx.doi.org/10.3390/pr10122738.

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For the purpose of studying compact strip production (CSP) funnel-shaped mold and flexible thin-slab rolling (FTSR) funnel-shaped mold, a three-dimensional (3D) multi-field coupling mathematical model was established to describe the electromagnetic braking (EMBr) continuous casting process. To investigate the metallurgical effect of EMBr in the CSP and FTSR funnel-shaped thin-slab molds, a Reynolds-averaged Navier–Stokes (RANS) turbulence model, together with an enthalpy–porosity approach, was established to numerically simulate the effect of ruler EMBr on the behaviors of melt flow, heat transfer, solidification, and inclusion movement in high-speed casting. The simulation results indicate that the application of ruler EMBr in the CSP and FTSR molds shows great potential to improve the surface temperature of molten steel and reduce the penetration depth of downward backflow. This contributes to the melting of the slag rim near the meniscus region and facilitates the floating removal of the inclusions in the molten pool. In addition, in comparison with the case of no EMBr, the parametric study shows that the braking effect of ruler EMBr with an electromagnetic parameter of 0.5 T can enhance the upward backflow in the two high-speed thin-slab molds. The enhanced upward backflow can successfully entrain the inclusions to the top of the mold and improve the activity of surface fluctuations to avoid the formation of the slag rim. For instance, for the ruler EMBr applied to the FTSR mold, the maximum amplitude of surface fluctuation and the floatation removal quantity of inclusions with a diameter of 100 μm are increased by 4.6 percent and 51 percent, respectively.

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10

Dilek, Yildirim, and Limei Tang. "Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics." Geological Magazine 158, no. 1 (December 10, 2020): 118–42. http://dx.doi.org/10.1017/s0016756820001211.

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AbstractOur field-based geochemical studies of the Triassic, Jurassic and Cretaceous granitoids on Hainan Island indicate that their magmas had different geochemical affinities, changing from alkaline in the Triassic through ocean island basalt (OIB) in the Jurassic, to calc-alkaline in the Cretaceous. We show that these changes in the geochemical affinities of the Mesozoic granitoids on Hainan and in SE China reflect different melt sources and melt evolution patterns through time. Our new geodynamic model suggests that: (1) Triassic geology was controlled by flat-slab subduction of the palaeo-Pacific plate beneath SE China. This slab dynamics resulted in strong coupling between the lower and upper plates, causing push-over tectonics and contractional deformation in SE China. Flat subduction-induced edge flow and aesthenospheric uprising led to the production of high-K granites, syenites and mafic rocks. (2) Slab foundering, accelerated subduction rates and subduction hinge retreat in the Early Jurassic caused rapid rollback of the downgoing slab. Strong decoupling of the upper and lower plates resulted in pull-away tectonics, producing extensional deformation in SE China. Decompression melting of the upwelling aesthenosphere produced OIB-type melts, which interacted with the subcontinental lithospheric mantle (SCLM) to form A- and I-type granitoids. (3) Segmentation of the palaeo-Pacific plate in the Early Cretaceous resulted in steeply dipping slabs and their faster rollback, facilitating lithospheric-scale extension and oceanward migration of calc-alkaline magmatism. This extensional deformation played a significant role in the formation of metamorphic core complexes, widespread crustal melting and development of a Basin and Range-type tectonics and landscape evolution in SE China.

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11

Kim, Hee-Soo, and Ji-Joon Kim. "Predicting Grain Structure in Continuously-Cast Stainless Steel Slab." Korean Journal of Metals and Materials 61, no. 1 (January 5, 2023): 60–68. http://dx.doi.org/10.3365/kjmm.2023.61.1.60.

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Macrostructural features in continuously-cast stainless steel slabs such as the distribution of equiaxed and columnar grains, and microporosity, are crucial to the post-processes, and the mechanical properties of the final steel products. Among the methods for controlling grain structure during the continuous casting process, the application of electromagnetic stirring (EMS) during casting is known to alter the grain structure of the slab. In this study, we predicted macrostructural features in a continuous-cast stainless steel slab using computer simulation. We approximated the heat transfer system as a one-dimensional heat conduction model with solidification. The effect of EMS was investigated by introducing an effective thermal conductivity of the melt. We assumed that EMS caused turbulent flow, and enhanced the thermal conductivity. Columnar-to-equiaxed transition (CET) and microporosity were estimated with the models proposed by Hunt and Niyama, respectively. The effect of EMS on microporosity was negligible, and microporosity was inevitable in the centerline of the slab. EMS made a second equiaxed region between the outer wall and the center of the slab. Because the effective thermal conductivity was high due to EMS, the temperature field in the slab was distorted, and the Hunt criterion for CET was satisfied in the region. The CET results were compared and verified with cellular automata simulation. Various process parameters including casting speed, superheating, and the position of the EMS module, were examined to predict the macrostructure of the slab.

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12

Wu, Yangming, Feng Guo, Xuan-Ce Wang, Bo Zhang, Xiaobing Zhang, Melesse Alemayehu, and Guoqing Wang. "Generation of Late Cretaceous Ji’an basalts through asthenosphere-slab interaction in South China." GSA Bulletin 132, no. 5-6 (May 1, 2020): 1316–32. http://dx.doi.org/10.1130/b35196.1.

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Abstract Recycled crustal components have been widely identified in the source of continental basalts with geochemical features similar to oceanic island basalts (OIBs). However, the mechanism of how these recycled materials are involved remains highly debatable. Here we conduct comprehensive geochemical analyses (including whole-rock, olivine, and melt inclusion) and numerical modeling on Late Cretaceous Ji’an basalts from South China interior, aiming to investigate the possible role of recycled crustal components in basalt petrogenesis driven by the subducted paleo-Pacific oceanic plate. The Ji’an basalts show geochemical characteristics akin to OIBs and have depleted asthenospheric mantle-like Sr-Nd-Pb-Hf isotopic compositions with moderately radiogenic Os. Their olivine-hosted melt inclusions have low H2O and highly negative δD values and olivine phenocrysts are mainly characterized by depletion of 18O with δ18O values lowering to 3.9‰. These features are consistent with positive Sr and Eu anomalies in some whole-rock samples. The combined geochemical data suggest that the primary magmas were derived from an asthenospheric mantle enriched by melts from an altered gabbroic oceanic crust, which had experienced intensive dehydration. Further numerical modeling shows that melting of the dehydrated oceanic crust can occur along the torn flank of the subducting lithosphere, in the case that the slab is strongly thinned and fractured. The low δ18O preserved in olivine and the estimated slab age (<300 Ma) from the radiogenic whole-rock Os and Pb compositions also require the involvement of a recently recycled slab, probably represented by the subducted paleo-Pacific oceanic plate. Rollback of the subducting paleo-Pacific slab might create a slab window, in which melt from the torn/fractured slab reacted with the upwelling asthenosphere to form an enriched mantle source for the Ji’an basalts and similar counterparts.

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13

Dilek, Yildirim, and Yujiro Ogawa. "Subduction zone processes and crustal growth mechanisms at Pacific Rim convergent margins: modern and ancient analogues." Geological Magazine 158, no. 1 (December 11, 2020): 1–12. http://dx.doi.org/10.1017/s0016756820001326.

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AbstractContinents grow mainly through magmatism, relamination, accretionary prism development, sediment underplating, tectonic accretion of seamounts, oceanic plateaus and oceanic lithosphere, and collisions of island arcs at convergent margins. The modern Pacific–Rim subduction zone environments present a natural laboratory to examine the nature of these processes. The papers in this special issue focus on the: (1) modern and ancient accretionary margins of Japan; (2) arc–continent collision zone in the Taiwan orogenic belt; (3) accreting versus non-accreting convergent margins of the Americas; and (4) several examples of ancient convergent margins of East Asia. Subduction erosion and sediment underplating are important processes, affecting the melt evolution of arc magmas by giving them special crustal isotopic characteristics. Oblique arc–continent collisions cause strong deformation partitioning that results in orogen-parallel extension, crustal exhumation and wrench faulting in the hinterland, and thrust faulting–folding in the foreland. Trench-parallel widths of subducting slabs exert major control on slab geometries, the degree of coupling–decoupling between the lower and upper plates, and subduction velocity partitioning. An initially large width of the subducting Palaeo-Pacific Plate against East Asia caused flat subduction and resistance to slab rollback during the Triassic Period. These conditions resulted in shortening across SE China. Foundering and delamination of the flat slab during the Early Jurassic Epoch led to slab segmentation and reduced slab widths, followed by slab steepening and rollback. This pull-away tectonics induced lithospheric extension and magmatism in SE China during Late Jurassic – Cretaceous time. Melting of subducted carbonaceous sediments commonly produces networks of silicate veins in CLM that may subsequently undergo partial melting, producing ultrapotassic magmas.

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14

Chen, Chao, Guo Guang Cheng, Hai Bo Sun, Xin Chao Wang, and Jia Quan Zhang. "Optimization of Flow Control Devices in a Stainless Steel Tundish." Advanced Materials Research 476-478 (February 2012): 156–63. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.156.

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Optimization of FCD design in a single strand slab tundish producing stainless steel is carried out by physical modelling using a 0.4 scale water model and mathematical modelling study. Reducing the residual metal volume at the end of casting, promoting the near-surface plug flow for inclusions removal and improving the transient slab quality are concerned, the optimized FCD is two dams and an impact pad, among them the dam1 (close to ladle shroud) with two 30 degrees upward inclined drain holes, another dam2 (close to tundish exit) is bottom rectangular-grooved which is beneficial for reducing the residual metal volume. Besides, the height of impact pad and drain holes must be concerned simultaneously, in the present study the height is 20mm and 60mm, respectively. Compared with turbulence inhibitors, impact pad will decrease the melt exposed to air at the steady state of casting. The holes at the higher level of dam may cause slag entrapment during the refilling process of ladle change operation.

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15

Gushchin, V. N., A. V. Kuklev, and V. M. Parshin. "Hydrostabilization of the melt supply to slab molds in continuous casting." Steel in Translation 37, no. 7 (July 2007): 604–6. http://dx.doi.org/10.3103/s0967091207070121.

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16

Zhang, Yunying, Chao Yuan, Min Sun, Xiaoping Long, Zongying Huang, Yingde Jiang, Pengfei Li, and Long Du. "Two late Carboniferous belts of Nb-enriched mafic magmatism in the Eastern Tianshan: Heterogeneous mantle sources and geodynamic implications." GSA Bulletin 132, no. 9-10 (January 7, 2020): 1863–80. http://dx.doi.org/10.1130/b35366.1.

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Abstract Identification of subduction to post-collisional tectonic transitions is critical to the study of orogenic belts. To characterize such a transition in the Tianshan Orogenic Belt, a systematic study was conducted on the late Carboniferous (305–301 Ma) Hongshankou dolerite and Dikan’er basalt of Eastern Tianshan. The Hongshankou dolerites have relatively high Ti and Nb contents, akin to Nb-enriched arc basalts. Based on the Nb/La ratios, these dolerites can be divided into low-Nb/La (0.35–0.40) and high-Nb/La (0.67–1.4) groups, which were likely derived respectively from slab melt-metasomatized mantle wedge and a mixed mantle source involving depleted super-slab and enriched sub-slab asthenospheric components. Like the low-Nb/La dolerites, the Dikan’er basalts possess low Nb/La (0.42–0.46) ratios, suggesting a mantle source previously modified by slab components. In addition, the Dikan’er basalts have variable Nb contents and can be grouped into normal arc basalts and Nb-rich basalts that can be attributed to a common mantle source with different degrees of mantle melting, as demonstrated by the positive correlations of La/Sm with La and Nb. By integrating available data, two late Carboniferous belts of Nb-enriched mafic magmatism are recognized in the Eastern Tianshan, with one in the Yamansu arc (336–301 Ma) and the other in the Bogda Mountains (305–301 Ma). The former is characterized by low Nb/La (<0.6) ratios, reflecting derivation from mantle metasomatized by slab-derived melt during a subduction process; the latter exhibits an abrupt Nb/La increase from 0.6 to 1.4, indicating significant input of sub-slab asthenospheric mantle that was probably induced by slab break off. Accordingly, we propose that the tectonic transition from subduction to post-collision in the Eastern Tianshan occurred in the latest Carboniferous (305–301 Ma) and was marked by the abrupt input of deep and enriched asthenospheric mantle.

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17

Cai, Yue, Alexandra LaGatta, Steven L. Goldstein, Charles H. Langmuir, Arturo Gómez-Tuena, Ana Lillian Martín-del Pozzo, and Gerardo Carrasco-Núñez. "Hafnium isotope evidence for slab melt contributions in the Central Mexican Volcanic Belt and implications for slab melting in hot and cold slab arcs." Chemical Geology 377 (June 2014): 45–55. http://dx.doi.org/10.1016/j.chemgeo.2014.04.002.

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18

Vlasov, М. А., V. A. Egorov, A. G. Lyzhin, and D. V. Sushnikov. "Application of “flat’ closed-bottom submerged nuzzles for decreasing rejections of slabs because of longitudinal cracks." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 76, no. 6 (July 21, 2020): 556–58. http://dx.doi.org/10.32339/0135-5910-2020-6-556-558.

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In the process of steel continuous casting it was discovered, that due to relatively small distance between a submerged nuzzle and a mold walls, formation of “scull crust” takes place in the area of small and big radius of the billet. It resulted in deterioration of heat-away in mold, conditions are formed for origination of longitudinal cracks following its further opening in the CCM secondary cooling zone. To decrease the number of rejections continuously casted slab billets due to existence of longitudinal cracks, it was proposed to use “flat” closed-bottom submerged nuzzles. It was shown, that in contrast to cylindrical form of a series closed-bottom submerged nuzzle, the proposed one has rectangular section with chamfered butt facet in the are of nuzzle submerging into the mold melt, which enables to ensure better fluidity of slag-forming mixture between the nuzzle and the mold walls. This effect results in onsiderable improving evenness of heat-away. To confirm the effectiveness of the pilot submerged nuzzles application, in 2019 their pilot-industrial tests were accomplished in the campaign of casting of carbon and peritectic steels to produce 200 mm thick slabs at CCM No. 4. In the process of the tests when casting various steels, the same slag-forming mixtures were used. As a result of the tests the decrease of rejections of continuously casted slabs due to longitudinal cracks formation was confirmed.

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19

Shimizu, Yohei, Shoji Arai, Tomoaki Morishita, Hisayoshi Yurimoto, and Fernando Gervilla. "Petrochemical characteristics of felsic veins in mantle xenoliths from Tallante (SE Spain): an insight into activity of silicic melt within the mantle wedge." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 95, no. 1-2 (March 2004): 265–76. http://dx.doi.org/10.1017/s0263593300001061.

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ABSTRACTFelsic and related veins within mantle-derived peridotite xenoliths from Tallante, Spain, were examined in order to understand the mantle-wedge processes related to the behaviour of Si-rich melt. The thickest part of the vein has a quartz diorite lithology, and is composed mainly of quartz and plagioclase, with pyroxenes, hydrous mineral, apatite, zircon and rutile present as minor phases. The thinner parts are free of quartz and predominantly composed of plagioclase. Orthopyroxene always intervenes between the internal part (plagioclase ± quartz) and host peridotite, indicating that it is a product of interaction between silica-oversaturated melt and olivine. This indicates that a sufficiently high melt/wall rock ratio enabled the melt to retain its silicaoversaturated character.The quartz diorite part has adakite-like geochemical signatures, except for negative Ba, Rb Eu and Sr anomalies, and positive Th and U anomalies. These negative anomalies indicate that fractionation of plagioclase and hydrous minerals was achieved between the upper most mantle and the slab melting zone. The shape of the rare-earth element (REE) pattern of clinopyroxene in quartz diorite is strikingly similar to that of clinopyroxene phenocrysts from Aleutian adakites. However, the former has one order higher REE contents than the latter, except for Eu which shows a prominent negative spike. This feature was caused by the precipitation of large amounts of plagioclase and small amounts of clinopyroxene from a fractionated adakitic melt before and during solidification. This adakitic melt was produced by partial melting of a detached and sinking slab beneath the Betic area in the Tertiary.

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20

Wang, Changjun, Zhongqiu Liu, and Baokuan Li. "Combined Effects of EMBr and SEMS on Melt Flow and Solidification in a Thin Slab Continuous Caster." Metals 11, no. 6 (June 11, 2021): 948. http://dx.doi.org/10.3390/met11060948.

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Electromagnetic fields have emerged as powerful tools for addressing current problems in thin slab continuous casting processes in the iron and steel industry. Substantial studies have been undertaken on the fundamental effects of electromagnetic brakes (EMBr) and strand electromagnetic stirring (SEMS). However, little attention has been focused on melt flow and solidification in a thin slab continuous caster with the simultaneous application of an EMBr and SEMS. The present study aimed to predict transient fields in the caster using a large eddy simulation and an enthalpy-porosity method. The electric potential method was applied in the braking process, and the conductivity change with solidification was considered. The suppressive effect on the intensity of the nozzle jet, the balance effect on the mold flow, and a dispersion effect could be observed. The dispersion effect was a novel finding and was beneficial to a flatter nozzle jet. In contrast, SEMS caused a highly turbulent flow in the strand. A large vortex could be observed in the casting direction. The solidified shell became more uniform, and the solidification rate became obviously slower. These findings supported the view that a high-quality thin slab can be produced by the application of an EMBr and SEMS.

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21

Coltorti, M., C. Bonadiman, B. Faccini, T. Ntaflos, and F. Siena. "Slab melt and intraplate metasomatism in Kapfenstein mantle xenoliths (Styrian Basin, Austria)." Lithos 94, no. 1-4 (March 2007): 66–89. http://dx.doi.org/10.1016/j.lithos.2006.07.003.

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22

Bourdon, Erwan, Jean-Philippe Eissen, Marc-André Gutscher, Michel Monzier, Pablo Samaniego, Claude Robin, Claire Bollinger, and Joseph Cotten. "Slab melting and slab melt metasomatism in the Northern Andean Volcanic Zone : adakites and high-Mg andesites from Pichincha volcano (Ecuador)." Bulletin de la Société Géologique de France 173, no. 3 (May 1, 2002): 195–206. http://dx.doi.org/10.2113/173.3.195.

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Abstract Situated in the fore-arc of the Northern Volcanic Zone (NVZ) of the Andes in Ecuador, Pichincha volcano is an active edifice where have been erupted unusual magmas as adakites and high-Mg andesites. The particular geodynamic setting of the ecuadorian margin (i.e. the flat subduction of the Carnegie Ridge) suggests that thermo-barometric conditions for the partial melting of the oceanic crust are accomplished beneath this volcano. Pichincha adakites possess all the geochemical and isotopic characteristics of slab melts described in various other arc settings. High-Mg andesites with geochemical characteristics close to those of adakites present strong enrichments in MgO that suggest that, once they were produced by ca. 10 % partial melting of the downgoing subducted slab, some adakites en route to the surface strongly interacted with the peridotitic mantle wedge. Adakitic magmas could then represent, as in many other arcs where slab melting occurs, the principal metasomatic agent of the mantle in the NVZ in Ecuador.

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Xue, Shuo, and Yuan Li. "Pyrrhotite–silicate melt partitioning of rhenium and the deep rhenium cycle in subduction zones." Geology 50, no. 2 (November 9, 2021): 232–37. http://dx.doi.org/10.1130/g49374.1.

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Abstract The Re-Os isotopic system serves as an important tracer of recycled crust in Earth's deep mantle because of the large Re/Os ratios and time-integrated enrichment of radiogenic Os in Earth's crust. However, the Re distribution in Earth's known reservoirs is mass imbalanced, and the behavior of Re during subduction remains little understood. We performed laboratory experiments to determine the partition coefficients of Re between pyrrhotite and silicate melt () at 950–1080°C, 1–3 GPa, and oxygen fugacities (in log units relative to the fayalite-magnetite-quartz [FMQ] buffer) of FMQ–1.3 to FMQ +2. The obtained values are 200–25,000, which increase with decreasing oxygen fugacity and the total iron content (FeOtot) of silicate melt but decrease with increasing temperature or decreasing pressure. Applying to constrain the behavior of Re during slab melting demonstrates that slab melts contribute minimal Re to the sub-arc mantle, with most Re dissolved in sulfides subducted into Earth's deep mantle. Deep storage of recycled oceanic basalts and sediments can explain the mass imbalance of Re in Earth's primitive mantle, depleted mantle, and crust.

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24

Rajani, Rajanikanta. "Geochemistry of Khandadharpahar-Thakuranipahar metabasites from the western Singhbhum Craton, eastern India: implications for subduction-zone tectonics and mantle-wedge metasomatism." Geologica Acta 20 (September 16, 2022): 17. http://dx.doi.org/10.1344/geologicaacta2022.20.11.

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The identification of new rock types in the volcano-sedimentary sequences of the Singhbhum Craton has attractedmuch attention in recent years. The present study deals on newly identified Nb-Enriched Basalts (NEB) from theKhandadharpahar-Kadakala-Thakuranipahar (KKT) section, western Singhbhum Craton, which is comparablein composition to basalts-basaltic andesites and calk-alkaline in character. These metabasites have a porphyritictexture with phenocrysts of pyroxene and plagioclase, as well as a groundmass that has metamorphosed to thegreenschist facies. High Nb contents (7.5-22.8ppm) combined with high (Nb/Th)PM (0.28-0.59), (Nb/La)PM (0.40-0.69) and Nb/U (11.7-34.4) ratios, compared to arc basalts ((Nb/Th)PM= 0.10-1.19; (Nb/La)PMn 0.17-0.99, Nb/U<10), characterized them as NEB. Negative Nb, Zr, Hf and Ti anomalies, and Nb/Th vs La/Nb and Th/Nb vs. La/Sm relationships, collectively indicate typical arc volcanics. The available geochemical parameters suggest a genesisof KKT metabasites through i) slab melt migration from the downgoing oceanic crust, ii) low-degree melting ofthe garnet-bearing peridotite in the mantle wedge metasomatized by the slab melts, iii) slab melt - peridotiteinteraction triggering increasing Nb concentrations and iv) NEB generation in an arc-related environment. Thediscovery of KKT NEB sheds new information on Paleoproterozoic subduction-zone processes and crustal growthin the Singhbhum craton.

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25

McGary, R. Shane, Rob L. Evans, Philip E. Wannamaker, Jimmy Elsenbeck, and Stéphane Rondenay. "Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier." Nature 511, no. 7509 (July 2014): 338–40. http://dx.doi.org/10.1038/nature13493.

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26

Rosenbaum, Gideon, Mike Sandiford, John Caulfield, and Jennifer M. Garrison. "A trapdoor mechanism for slab tearing and melt generation in the northern Andes." Geology 47, no. 1 (November 9, 2018): 23–26. http://dx.doi.org/10.1130/g45429.1.

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27

Zhu, Guizhi, Taras Gerya, and David A. Yuen. "Melt evolution above a spontaneously retreating subducting slab in a three-dimensional model." Journal of Earth Science 22, no. 2 (April 2011): 137–42. http://dx.doi.org/10.1007/s12583-011-0165-x.

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28

Francalanci, Lorella, and Georg F. Zellmer. "Magma Genesis at the South Aegean Volcanic Arc." Elements 15, no. 3 (June 1, 2019): 165–70. http://dx.doi.org/10.2138/gselements.15.3.165.

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The South Aegean volcanic arc consists of five volcanic fields, with products that range from medium- and high-K calc-alkaline basalts to rhyolites. Parental magmas are generated by variable proportions of decompression and flux melting of a mantle source metasomatized by sediment melts and aqueous fluids released from the subducted slab. Fluid/sediment ratios are lowest in Santorini (Greece) where high lithospheric extension results in a predominance of decompression melting, shallower magma storage, and more mafic volcanism than elsewhere in the arc. Contributions from slab sediment melt decrease from west to east. With the lowest convergence rate and surface heat flux of any continental arc worldwide, the South Aegean is an ideal natural laboratory for studying arc magmatism at low magma production rates.

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29

Veng, Torben, and Torben Skettrup. "Dilute-melt, proton-exchange slab waveguides in LiNbO_3: a new fabrication and characterization method." Applied Optics 36, no. 24 (August 20, 1997): 5941. http://dx.doi.org/10.1364/ao.36.005941.

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30

König, S., S. Schuth, C. Münker, and C. Qopoto. "Petrogenesis of high-Mg andesites, Simbo Volcano, Solomon Islands: evidence for slab melt contributions." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A329. http://dx.doi.org/10.1016/j.gca.2006.06.665.

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31

Hole, Malcolm J., and Andy D. Saunders. "The generation of small melt-fractions in truncated melt columns: constraints from magmas erupted above slab windows and implications for MORB genesis." Mineralogical Magazine 60, no. 398 (February 1996): 173–89. http://dx.doi.org/10.1180/minmag.1996.060.398.12.

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AbstractAt a number of locations along the Pacific margin of the Americas and west Antarctica, small volumes of alkalic basalts were erupted following successive ridge crest-trench collisions. The basalts were generated as a result of upwelling of asthenosphere through windows in the subducted plate. There is no evidence for local high temperature mantle plumes or significant lithospheric extension associated with these basalts. For the best sampled area, the Antarctic Peninsula, mean values for fractionation-corrected iron content (FeO*) vary from 6.9 to 10.6 wt.%, and for Na2O (Na8.0) from 3.25 to 4.6 wt.%, implying generation of small melt-fractions at variable mean pressures. The results of rare earth element inversion modelling yield a melt generation interval of 100 to 52 km, with a maximum melt fraction of c. 7% generated from a MORB-like source at Tp 1300°C. Trace element and isotope systematics are also consistent with the generation of the basalts from a MORB-like source.Mean pressures of melt generation increase with increasing distance from the original trench, but trace element and Na8.0 data suggest that there is no systematic variation in extent of melting with distance from the trench. The data are consistent with a model whereby a MORB melting column, initially intersecting the peridotite solidus at between 15 and 30 kbar, is truncated by a lithospheric cap which thickens from c. 15–20 km (≈ 5–8 kbar) up to a maximum of c. 50 km (≈ 15 kbar), such that the mean pressures of melting increase with increasing distance from the palaeo-trench. The MORB-like major element geochemistry of basalt samples closest to the ancestral trench are consistent with initial intersection of the peridotite solidus at low pressures (c. 15 kbar). For areas of thickest lithosphere, mean pressures of melt generation are higher, but extents of melting are lower than for a MORB melting column with a similar initial pressure of intersection of the peridotite solidus. All these basalts therefore potentially represent analogues for the small melt-fraction precursors to the generation of MOR tholeiites.Thermal constraints suggest that these low volume, small melt-fractions, were generated with CO2 on the solidus, because mean pressures of melt generation are greater than the pressure of intersection of the Tp 1300°C mantle adiabat and the dry peridotite solidus. Potentially, all MORB may be generated initially with CO2 on the solidus, and if this is correct, it does not require thermal anomalies to generate large extents of melting at high mean pressures.

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32

Eberhart-Phillips, Donna, Stephen Bannister, and Martin Reyners. "Attenuation in the mantle wedge beneath super-volcanoes of the Taupo Volcanic Zone, New Zealand." Geophysical Journal International 220, no. 1 (October 9, 2019): 703–23. http://dx.doi.org/10.1093/gji/ggz455.

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SUMMARY The Taupo Volcanic Zone has a 120-km-long section of rhyolitic volcanism, within which is a 60-km-long area of supervolcanoes. The underlying subducted slab has along-strike heterogeneity due to the Hikurangi Plateau's prior subduction history. We studied 3-D Qs (1/attenuation) using t* spectral decay from local earthquakes to 370-km depth. Selection emphasized those events with data quality to sample the low Qs mantle wedge, and Qs inversion used varied linking of nodes to obtain resolution in regions of sparse stations, and 3-D initial model. The imaged mantle wedge has a 250-km-long 150-km-wide zone of low Qs (<300) at 65–85 km depth which includes two areas of very low Qs (<120). The most pronounced low Qs feature underlies the Mangakino and Whakamaru super-eruptive calderas, with inferred melt ascending under the central rift structure. The slab is characterized by high Qs (1200–2000), with a relatively small area of reduction in Qs (<800) underlying Taupo at 65-km depth, and adjacent to the mantle wedge low Qs. This suggests abundant dehydration fluids coming off the slab at specific locations and migrating near-vertically upward to the volcanic zone. The seismicity in the subducted slab has a patch of dense seismicity underlying the rhyolitic volcanic zone, consistent with locally abundant fractures and fluid flux. The relationship between the along-arc and downdip slab heterogeneity and dehydration implies that patterns of volcanism may be strongly influenced by large initial outer rise hydration which occurred while the edge of the Hikurangi Plateau hindered subduction. A second very low Qs feature is 50-km west above the 140-km-depth slab. The distinction suggests involvement of a second dehydration peak at that depth, consistent with some numerical models.

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33

Sajona, Fernando G., Rene C. Maury, Gaëlle Prouteau, Joseph Cotten, Pieree Schiano, Hervé Bellon, and Laure Fontaine. "Slab melt as metasomatic agent in island arc magma mantle sources, Negros and Batan (Philippines)." Island Arc 9, no. 4 (July 18, 2008): 472–86. http://dx.doi.org/10.1111/j.1440-1738.2000.00295.x.

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34

Bourdon, E. "Slab Melt Metasomatism Beneath the North Andean Volcanic Zone? Insight from Antisana Volcano Rocks (Ecuador)." Mineralogical Magazine 62A, no. 1 (1998): 209–10. http://dx.doi.org/10.1180/minmag.1998.62a.1.111.

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35

Sajona, Fernando G., Rene C. Maury, Gaelle Prouteau, Joseph Cotten, Pieree Schiano, Herve Bellon, and Laure Fontaine. "Slab melt as metasomatic agent in island arc magma mantle sources, Negros and Batan (Philippines)." Island Arc 9, no. 4 (December 2000): 472–86. http://dx.doi.org/10.1046/j.1440-1738.2000.00295.x.

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36

Efremov, S. V., A. M. Spiridonov, and N. A. Goryachev. "Slab Melt as a Potential Source of Profiling Elements of Gold and Heavy Metal Deposits." Doklady Earth Sciences 479, no. 2 (April 2018): 486–90. http://dx.doi.org/10.1134/s1028334x1804013x.

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37

Gao, Yongfeng, Zengqian Hou, Balz S. Kamber, Ruihua Wei, Xiangjin Meng, and Rongsheng Zhao. "Adakite-like porphyries from the southern Tibetan continental collision zones: evidence for slab melt metasomatism." Contributions to Mineralogy and Petrology 153, no. 1 (September 23, 2006): 105–20. http://dx.doi.org/10.1007/s00410-006-0137-9.

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38

Shatsky, Vladislav, Dmitry Zedgenizov, Alexey Ragozin, and Viktoriya Kalinina. "Silicate Melt Inclusions in Diamonds of Eclogite Paragenesis from Placers on the Northeastern Siberian Craton." Minerals 9, no. 7 (July 5, 2019): 412. http://dx.doi.org/10.3390/min9070412.

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New findings of silicate-melt inclusions in two alluvial diamonds (from the Kholomolokh placer, northeastern Siberian Platform) are reported. Both diamonds exhibit a high degree of N aggregation state (60–70% B) suggesting their long residence in the mantle. Raman spectral analysis revealed that the composite inclusions consist of clinopyroxene and silicate glass. Hopper crystals of clinopyroxene were observed using scanning electron microscopy and energy-dispersive spectroscopic analyses; these are different in composition from the omphacite inclusions that co-exist in the same diamonds. The glasses in these inclusions contain relatively high SiO2, Al2O3, Na2O and, K2O. These composite inclusions are primary melt that partially crystallised at the cooling stage. Hopper crystals of clinopyroxene imply rapid cooling rates, likely related to the uplift of crystals in the kimberlite melt. The reconstructed composition of such primary melts suggests that they were formed as the product of metasomatised mantle. One of the most likely source of melts/fluids metasomatising the mantle could be a subducted slab.

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39

Förster, Michael W., Yannick Bussweiler, Dejan Prelević, Nathan R. Daczko, Stephan Buhre, Regina Mertz-Kraus, and Stephen F. Foley. "Sediment-Peridotite Reaction Controls Fore-Arc Metasomatism and Arc Magma Geochemical Signatures." Geosciences 11, no. 9 (September 3, 2021): 372. http://dx.doi.org/10.3390/geosciences11090372.

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Subduction of oceanic crust buries an average thickness of 300–500 m of sediment that eventually dehydrates or partially melts. Progressive release of fluid/melt metasomatizes the fore-arc mantle, forming serpentinite at low temperatures and phlogopite-bearing pyroxenite where slab surface reaches 700–900 °C. This is sufficiently high to partially melt subducted sediments before they approach the depths where arc magmas are formed. Here, we present experiments on reactions between melts of subducted sediments and peridotite at 2–6 GPa/750–1100 °C, which correspond to the surface of a subducting slab. The reaction of volatile-bearing partial melts derived from sediments with depleted peridotite leads to separation of elements and a layered arrangement of metasomatic phases, with layers consisting of orthopyroxene, mica-pyroxenite, and clinopyroxenite. The selective incorporation of elements in these metasomatic layers closely resembles chemical patterns found in K-rich magmas. Trace elements were imaged using LA-ICP-TOFMS, which is applied here to investigate the distribution of trace elements within the metasomatic layers. Experiments of different duration enabled estimates of the growth of the metasomatic front, which ranges from 1–5 m/ky. These experiments explain the low contents of high-field strength elements in arc magmas as being due to their loss during melting of sedimentary materials in the fore-arc.

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40

Chen, Yunfeng, Yu Jeffrey Gu, Larry M. Heaman, Lei Wu, Erdinc Saygin, and Shu-Huei Hung. "Reconciling seismic structures and Late Cretaceous kimberlite magmatism in northern Alberta, Canada." Geology 48, no. 9 (May 29, 2020): 872–76. http://dx.doi.org/10.1130/g47163.1.

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Abstract The Late Cretaceous kimberlites in northern Alberta, Canada, intruded into the Paleoproterozoic crust and represent a nonconventional setting for the discovery of diamonds. Here, we examined the origin of kimberlite magmatism using a multidisciplinary approach. A new teleseismic survey reveals a low-velocity (−1%) corridor that connects two deep-rooted (>200 km) quasi-cylindrical anomalies underneath the Birch Mountains and Mountain Lake kimberlite fields. The radiometric data, including a new U-Pb perovskite age of 90.3 ± 2.6 Ma for the Mountain Lake intrusion, indicate a northeast-trending age progression in kimberlite magmatism, consistent with the (local) plate motion rate of North America constrained by global plate reconstructions. Taken together, these observations favor a deep stationary (relative to the lower mantle) source region for kimberlitic melt generation. Two competing models, mantle plume and slab subduction, can satisfy kinematic constraints and explain the exhumation of ultradeep diamonds. The plume hypothesis is less favorable due to the apparent age discrepancy between the oldest kimberlites (ca. 90 Ma) and the plume event (ca. 110 Ma). Alternatively, magma generation may have been facilitated by decompression of hydrous phases (e.g., wadsleyite and ringwoodite) within the mantle transition zone in response to thermal perturbations by a cold slab. The three-dimensional lithospheric structures largely controlled melt migration and intrusion processes during the Late Cretaceous kimberlite magmatism in northern Alberta.

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41

Begum, Latifa, and Mainul Hasan. "A Numerical Study of 3D Turbulent Melt Flow and Solidification in a Direct Chill Slab Caster with an Open-Top Melt Feeding System." Numerical Heat Transfer, Part A: Applications 67, no. 7 (December 10, 2014): 719–45. http://dx.doi.org/10.1080/10407782.2014.949143.

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42

Begum, Latifa, and Mainul Hasan. "A Numerical Study of 3D Turbulent Melt Flow and Solidification in a Direct Chill Slab Caster with a Porous Combo Bag Melt Distributor." Numerical Heat Transfer, Part A: Applications 67, no. 7 (December 10, 2014): 746–70. http://dx.doi.org/10.1080/10407782.2014.949159.

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43

Olive, Valérie, Réjean Hébert, and Michel Loubet. "Isotopic and trace element constraints on the genesis of a boninitic sequence in the Thetford Mines ophiolitic complex, Quebec, Canada." Canadian Journal of Earth Sciences 34, no. 9 (September 1, 1997): 1258–71. http://dx.doi.org/10.1139/e17-100.

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The Mont Ham Massif (part of the Thetford Mines ophiolite, south Quebec) represents a magmatic sequence made up of tholeiitic and boninitic derived products. A geochemical study confirms the multicomponent mixing models that have been classically advanced for the source of boninites, with slab-derived components added to the main refractory harzburgitic peridotite. An isochron diagram of the boninitic rocks is interpreted as a mixing trend between two components: (i) a light rare earth element (LREE) enriched component (A), interpreted as slab-derived fluid–melts equilibrated with sedimentary materials (εNd = −3, 147Sm/144Nd = 0.140), and (ii) a LREE-depleted component (B) (0.21 < 147Sm/144Nd < 0.23), interpreted as slab-derived fluid–melt equilibrated with recycled Iapetus oceanic crust and equated to the Nd-isotope characteristics of the Iapetus mantle (εNd = 9). A multicomponent source is also necessary to explain the Nd-isotope and trace element composition of the tholeiites, which are explained by the melting of a more fertile, lherzolitic mantle and (or) mid-ocean ridge basalt source (component C), characterized by a large-ion lithophile element depleted pattern and an Iapetus mantle Nd isotopic composition (εNd = 9), mixed in adequate proportions with the two previously infered slab-derived components (A and B). The genesis of the boninites of Mont Ham is not significantly different from those of boninites located in the Pacific. An intraoceanic subduction zone appears to be an appropriate geodynamic environment for the Mont Ham ophiolitic sequence.

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Hanyu, Takeshi, James Gill, Yoshiyuki Tatsumi, Jun-Ichi Kimura, Keiko Sato, Qing Chang, Ryoko Senda, et al. "Across- and along-arc geochemical variations of lava chemistry in the Sangihe arc: Various fluid and melt slab fluxes in response to slab temperature." Geochemistry, Geophysics, Geosystems 13, no. 10 (October 2012): n/a. http://dx.doi.org/10.1029/2012gc004346.

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45

Rushmer, Tracy, and Matt Jackson. "Impact of melt segregation on tonalite-trondhjemite-granodiorite (TTG) petrogenesis." Transactions of the Royal Society of Edinburgh: Earth Sciences 97, no. 4 (2008): 325–36. http://dx.doi.org/10.1017/s0263593300001486.

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Abstract“In searching for the origin of granites, it is tempting to view them as purely chemical systems”(Pitcher 1979, p. 90)Although sophisticated geochemical studies tell us that tonolite-trondhjemite-granodiorite (TTG) plutonic complexes must be formed by partial melting of metabasaltic source material, they cannot tell us the tectonic regime in which this crust was formed, nor how large volumes of TTG magma can be generated. This study suggests that a solution to TTG arc crust formation requires a strongly interdisciplinary approach, to resolve the tectonic setting (slab melt verses mafic lowermost crust sources), the time and length scales for melting and extraction, and the role of melt segregation mechanisms in the formation of both Archean TTGs and more recent adakite-like magmas. The aim of this paper is to present an experimental approach which, when coupled with numerical models, allows some of these issues to be addressed. The experiments are designed to reproduce the local changes in bulk composition that are predicted to occur in response to buoyancy-driven melt segregation along grain edges and associated compaction of the solid residue. The preliminary study presented here documents the changes we observe in the melt composition and melt and solid phase modes between earlier direct partial melting and the new segregation equilibration experiments on metabasalt bulk compositions. The results suggest that if dynamic melt segregation and equilibrium processes are active, they may modify the normally robust geochemical indicators, such as Mg-numbers, which are typically used to develop models of TTG petrogenesis.

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46

van Hinsberg, Vincent, Catherine Crotty, Stan Roozen, Kristoffer Szilas, and Alexander Kisters. "Pressure–Temperature History of the >3 Ga Tartoq Greenstone Belt in Southwest Greenland and Its Implications for Archaean Tectonics." Geosciences 8, no. 10 (September 30, 2018): 367. http://dx.doi.org/10.3390/geosciences8100367.

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The Tartoq greenstone belt of southwest Greenland represents a well-preserved section through >3 Ga old oceanic crust and has the potential to provide important constraints on the composition and geodynamics of the Archaean crust. Based on a detailed structural examination, it has been proposed that the belt records an early style of horizontal convergent plate tectonics where elevated temperatures, compared to the modern-day, led to repeated aborted subduction and tonalite–trondhjemite–granodiorite (TTG) type melt formation. This interpretation hinges on pressure–temperature (P–T) constraints for the belt, for which only preliminary estimates are currently available. Here, we present a detailed study of the pressure–temperature conditions and metamorphic histories for rocks from all fragments of the Tartoq belt using pseudosection modelling and geothermobarometry. We show that peak conditions are predominantly amphibolite facies, but range from 450 to 800 °C at up to 7.5 kbar; reaching anatexis with formation of TTG-type partial melts in the Bikuben segment. Emplacement of the Tartoq segments into the host TTG gneisses took place at approximately 3 Ga at 450–500 °C and 4 kbar as constrained from actinolite–chlorite–epidote–titanite–quartz parageneses, and was followed by extensive hydrothermal retrogression related to formation of shear zone-hosted gold mineralisation. Tourmaline thermometry and retrograde assemblages in mafic and ultramafic lithologies constrain this event to 380 ± 50 °C at a pressure below 1 kbar. Our results show that the convergent tectonics recorded by the Tartoq belt took place at a P–T gradient markedly shallower than that of modern-day subduction, resulting in a hot, weak and buoyant slab unable to generate and transfer ‘slab pull’, nor sustain a single continuous downgoing slab. The Tartoq belt suggests that convergence was instead accomplished by under-stacking of slabs from repeated aborted subduction. The shallow P–T path combined with thermal relaxation following subduction stalling subsequently resulted in partial melting and formation of TTG melts.

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Kim, Kang Duk, and Seung Gu Kang. "Impact Sound Reduction Analysis of Concrete Slab Containing Artificial Lightweight Aggregates Fabricated Using a Sewage Sludge." Materials Science Forum 544-545 (May 2007): 581–84. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.581.

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The artificial lightweight aggregate (ALA) was fabricated using a sewage sludge produced from a municipal wastewater, and impact sound reduction analysis for concrete slab made with the ALA was done. Specific gravity of ALA decreased with the sewage sludge content due to the gas bloating caused by melt films on the surface of ALA, which is formed easily because of low temperature melting P2O5 and modifiers, CaO, MgO and K2O contained in the sewage sludge. And water absorption of ALA increased with the sewage sludge content owing to open pores which were formed by connecting an inside pore to a surface. A specific gravity of 10mm diameter ALA was lower than that of 7mm ALA since a trapped gas could not escape from the core to the surface of ALA due to longer moving distance. The ALA containing 20 wt% sludge sintered in a electric furnace showed a specific gravity 15% lower and water absorption 50% higher than that of ALA sintered in a rotary kiln. It might be attributed to easy release of gases during the pre-heat zone (600-1000oC) in the rotary kiln, resulting in densification of ALA. Light and heavy weight floor impact sound of concrete slab made with ALA were 63-72dB and 44-76dB respectively, similar to a general concrete slab. The unit weight of concrete slab made with ALA, however, was 18% lower than that of general one owing to the lightweight of ALA, so it could be suitable to applying for high-rise building.

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MALLMANN, GUILHERME, RAÚL O. C. FONSECA, and ADOLFO B. SILVA. "An experimental study of the partitioning of trace elements between rutile and silicate melt as a function of oxygen fugacity." Anais da Academia Brasileira de Ciências 86, no. 4 (December 2014): 1609–29. http://dx.doi.org/10.1590/0001-3765201420140014.

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Subduction zone or arc magmas are known to display a characteristic depletion of High Field Strength Elements (HFSE) relative to other similarly incompatible elements, which can be attributed to the presence of the accessory mineral rutile (TiO2) in the residual slab. Here we show that the partitioning behavior of vanadium between rutile and silicate melt varies from incompatible (∼0.1) to compatible (∼18) as a function of oxygen fugacity. We also confirm that the HFSE are compatible in rutile, with D(Ta)> D(Nb)>> (D(Hf)>/∼ D(Zr), but that the level of compatibility is strongly dependent on melt composition, with partition coefficients increasing about one order of magnitude with increasing melt polymerization (or decreasing basicity). Our partitioning results also indicate that residual rutile may fractionate U from Th due to the contrasting (over 2 orders of magnitude) partitioning between these two elements. We confirm that, in addition to the HFSE, Cr, Cu, Zn and W are compatible in rutile at all oxygen fugacity conditions.

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Kawamoto, T., M. Kanzaki, K. Mibe, K. N. Matsukage, and S. Ono. "Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism." Proceedings of the National Academy of Sciences 109, no. 46 (October 29, 2012): 18695–700. http://dx.doi.org/10.1073/pnas.1207687109.

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50

Gao, Yongfeng, Zhusen Yang, M. Santosh, Zengqian Hou, Ruihua Wei, and Shihong Tian. "Adakitic rocks from slab melt-modified mantle sources in the continental collision zone of southern Tibet." Lithos 119, no. 3-4 (October 2010): 651–63. http://dx.doi.org/10.1016/j.lithos.2010.08.018.

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