Cu-Zn isotope compositions of hydrothermal sediments from the southern Mid-Atlantic Ridge:implications to the sediment formation and mineral exploration

Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017.Sulfides and oxides in the samples were separated,and Cu and Zn isotope compositions were analyzed.Results show that the ranges ofδ^(65)Cu values of the bulk sediments,sulfides,and oxides were 0.36‰-2.46‰,-0.21‰-1.10‰,and 0.68‰-1.52‰,respectively.Theδ^(65)Cu values of sulfides in four samples(46II-14,46II-30,46III-06,and 46II-09)were relatively low(-0.21‰-0.50‰),corresponding to theδ^(65)Cu values of sulfides from inactive old hydrothermal chimneys in northern Mid-Atlantic Ridge(n MAR),suggesting that the sulfides in the sediments were originated from collapsed dead chimney mainly.While theδ^(65)Cu values of the other two samples(46III-02 and 46III-08)were relatively high(1.10‰-0.96‰),corresponding to theδ^(65)Cu values for active hydrothermal chimneys sulfides in n MAR,which indicated that the sulfides in these two samples might mainly come from sulfide particles settled from active hydrothermal plume.Because of the high density of sulfide particles,they tended to settle near the hydrothermal vents first.Therefore,highδ^(65)Cu values of sulfides in 46III-02 and 46III-08 implied that undiscovered active hydrothermal vents near the sampling positions of 46III-02 in the Xunmei hydrothermal field and 46III-08 in the Tongguan hydrothermal field.Theδ^(66)Zn values of hydrothermal sediments and sulfides ranged 0.11‰-0.43‰and 0.29‰-0.67‰,respectively.In the four samples from the Xunmei hydrothermal field,a positive correlation was found between the distance of the sampling position from sulfide mineralized spot and the Zn isotopic ratio,showing that the greater the distance from the mineralized spot,the heavier the Zn isotope composition as seen in two samples(46II-30 and 46II-14)of the Xunmei-3 spot.This result aligned with the findings of Wilkinson et al.(2005)and Baumgartner et al.(2023),suggesting that the lower the Zn isotope composition,the closer it is to the hydrothermal vent.However,in the Xunmei hydrothermal field,the Zn isotope composition in the other two samples(46III-02and 46III-06)showed the opposite trend.This indicated that there might be an active hydrothermal vent near the sampling location of sample 46III-02.This observation aligned with the Cu isotope analysis results.This study showed that Cu-Zn isotopes are good indicators for understanding the formation mechanisms of hydrothermal sediments and for locating active hydrothermal vents.

Hydrographic Characteristics and Oceanic Heat Flux in the Upper Arctic Ocean over the Alpha Ridge Observed by the DTOP Platform in 2018 and 2021

In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to 32.5.Comparison with World Ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August 2021.This anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation phase.During summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW core.After autumn,F_(w)^(OHF)was reduced(<2 Wm^(-2))except during rare events when it elevated F_(w)^(OHF)slightly.In addition,the intensive and widespread Ekman suction,which created a violent upwelling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.

Characteristics of the Deep Crustal Structure of the Greenland–Iceland–Faroe Ridge in the North Atlantic

The Greenland–Iceland–Faroe Ridge,located between the central eastern part of Greenland and the northwestern edge of Europe,spans across the North Atlantic.As the core component of the Greenland–Iceland–Faroe Ridge,the Iceland is an alkaline basalt area,which belongs to the periodic submarine magmatism and submarine volcano eruption resulting from mantle plume upwelling(Jiang et al.,2020).For the oceanic plateaus,the characteristics of the Iceland are closest to the continental crust,so the Iceland is considered the most suitable for simulating the earliest continental crust on the Earth(Reimink et al.,2014).

Discovery and characterization of a new hydrothermal field at 2°N on the slow-spreading Carlsberg Ridge

A new hydrothermal field(Tianshi)was discovered on the rift valley wall through plume anomaly surveys and geological work conducted in 2012 and 2018 between 2°35′N and 2°43′N of the slow-spreading Carlsberg Ridge(CR).Here,the results of two expeditions conducted to detect and characterize the new hydrothermal field are reported.Mineralogical and geochemical data,as well as 14 C ages of a sediment core collected near the field are presented to reveal the hydrothermal history.Results show that the Tianshi field is a basalt-hosted hydrothermal system.Geochemical data of the sediments collected near the field indicate a strong hydrothermal contribution,and hydrothermal Fe and Cu fluxes range from 30 to 155 mg/(cm^(2)·ka)and 0.59 to 11.49 mg/(cm^(2)·ka),respectively.Temporal variations in the fluxes of hydrothermal Fe indicate that there have been at least three amplified hydrothermal venting events(H 1,H 2,and H 3)in the Tianshi field over the last 35.2 ka,in 28.6-35.2 ka BP,22.0-27.6 ka BP,and 1.2-11.4 ka BP,respectively.Hydrothermal event H 2 was driven by an increased magmatic production associated with sea level fall during the Last Glacial Maximum,while event H 3 was promoted by tectonic activity associated with a rapid sea level rise.This study further verified the role of sea level change in modulating hydrothermal activity on mid-ocean ridges.

Nuclear charge radius predictions by kernel ridge regression with odd-even effects

The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25*model.In the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,respectively.For each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR method.The best among them was the RCHB model,with a root-mean-square deviation of 0.0092 fm.The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR method.The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.

Environmental characteristics of trace metals in seawater from the Ninety East Ridge in the Indian Ocean

The Ninety East Ridge in the Indian Ocean has complex and unique characteristics.The concentrations and distribution characteristics of 10 trace metals(V,Cr,Mn,Fe,Co,Ni,Cu,Cd,Pb,and U)in seawater from the Ninety East Ridge in the Indian Ocean were investigated.Results show that the average concentrations of different trace metals in all the collected seawater samples were 1.134μg/L for V,0.158μg/L for Cr,0.489μg/L for Mn,0.427μg/L for Fe,0.011μg/L for Co,0.395μg/L for Ni,0.403μg/L for Cu,0.097μg/L for Cd,0.139μg/L for Pb,and 3.470μg/L for U.Differences in the horizontal and vertical distributions of all measured trace metals were revealed,and the occurrence of high concentrations was nonuniform.In addition,the significant differences in the concentration distribution of different trace metals in seawater on both sides of the Ninety East Ridge present regional segmentation in the area for various trace metals in deep sea water.This study provided basic data for future investigations on the environmental and ecological impact of trace metals in the Indian Ocean and the potential water mass transport mechanism.

Microearthquake reveals the lithospheric structure at midocean ridges and oceanic transform faults

Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly understood.The large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic lithosphere.Previous studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃isotherm.However,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform faults.Several mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.

Molybdenum isotope composition of the upper mantle and its origin:insight from mid-ocean ridge basalt

The molybdenum(Mo)isotope system is pivotal in reconstructing marine redox changes throughout Earth’s history and has emerged as a promising tracer for igneous and metamorphic processes.Understanding its composition and variation across major geochemical reservoirs is essential for its application in investigating high-temperature processes.However,there is debate regarding theδ^(98/95)Mo value of the Earth’s mantle,with estimates ranging from sub-chondritic to super-chondritic values.Recent analyses of global mid-ocean ridge basalt(MORB)glasses revealed significantδ^(98/95)Mo variations attributed to mantle heterogeneity,proposing a two-component mixing model to explain the observed variation.Complementary studies confirmed the sub-chondriticδ^(98/95)Mo of the depleted upper mantle,suggesting remixing of subduction-modified oceanic crust as a plausible mechanism.These findings underscore the role of Mo isotopes as effective tracers for understanding dynamic processes associated with mantle-crustal recycling.

Structural features in the mid-southern section of the Kyushu–Palau Ridge based on satellite altimetry gravity anomaly

The Kyushu–Palau Ridge(KPR),an anti-S-shaped submarine highland at the center of the Philippine Sea Plate(PSP),is considered the residual arc of the Izu–Bonin–Mariana Island Arc,which retains key information about the cessation of the Western Philippine Basin(WPB)expansion and the Parece Vela Basin(PVB)breakup.Herein,using the new generation of satellite altimetry gravity data,high-precision seafloor topography data,and newly acquired ship-borne gravity data,the topographic and gravity characteristics of the KPR mid-southern section and adjacent region are depicted.The distribution characteristics of the faults were delineated using the normalized vertical derivative–total horizontal derivative method(NVDR-THDR)and the minimum curvature potential field separation method.The Moho depth and crustal thickness were inverted using the rapid inversion method for a double-interface model with depth constraints.Based on these results,the crust structure features in the KPR mid-southern section,and the“triangular”structure geological significance where the KPR and Central Basin Rift(CBR)of the WPB intersect are interpreted.The KPR crustal thickness is approximately 6–16 km,with a distinct discontinuity that is slightly thicker than the normal oceanic crust.The KPR mid-southern section crust structure was divided into four segments(S1–S4)from north to south,formed by the CBR eastward extension joint action and clockwise rotation of the PVB expansion axis and the Mindanao fault zone blocking effect.

Gravity Fault Subsidence and Beach Ridges Progradation in Quinta-Cassino (RS) Coastal Plain, Brazil

Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, however, low-frequency GPR survey to investigate fault-related depositional systems at greater depths. The Quinta-Cassino area in the Rio Grande do Sul Coastal Plain (RGSCP, Brazil) shows a wide strandplain that is made off by very long, continuous, and linear geomorphic features (beach ridges). This strandplain extends for ~70 km southward. The beach ridges show low-angle truncations against the Quinta escarpment, and also truncations in the strandplain. The traditional approach points that RGSCP was developed by juxtaposition of four lagoons/barrier systems as consequence of sea level changes;previous model assumes that no deformational episode occurred in RGSCP. The geophysical and geological surveys carried out in this area showed the existence of listric fault controlling the beach ridges in the escarpments and hanging-wall blocks. The radargrams could distinguish Pleistocene basement unit anticlockwise rotation, thickening of beach ridges radarfacies close to listric normal faults, and horst structures. These deformational features indicate that the extensional zone of a large-scale gravity-driven structure controlled the mechanical subsidence, the Holocene sedimentation and its stratigraphic and geomorphic features in the Quinta-Cassino area to build up an asymmetric delta. The results point to a new approach in dealing with RGSCP Holocene evolution.

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Recent investigations found that hydrothermal activity and sulfide mineralization occurs along the Southwest Indian Ridge（SWIR）. The Longqi and Duanqiao hydrothermal fields between 49° E and 53° E of the SWIR are two prospective mineralization areas discovered by Chinese scientists. With the aim to determine the mineralogical and chemical characteristics of sulfide minerals, we have conducted detailed studies for samples from the two areas using an optical microscope, X-ray diffractometer, scanning electron microscope, and electron microprobe. The mineralization processes in the Longqi area are divided into three main stages：（1） the low-medium-temperature stage： colloform pyrite（Py I） ＋ marcasite → euhedral pyrite（Py II）,（2） the high-temperature stage： isocubanite（±exsolved chalcopyrite） ＋ pyrrhotite → coarse-grained chalcopyrite（Ccp I）, and（3） the medium–low-temperature stage： sphalerite ＋ fine-grained chalcopyrite inclusions（Ccp II） → aggregates of anhedral pyrite（Py III） ± marcasite → Fe-oxide（-hydroxide） ＋ amorphous silica. The mineralization processes in the Duanqiao area are divided into two main stages：（1） the medium–high-temperature stage： subhedral and euhedral pyrite（Py I′） → coarse-grained chalcopyrite（Ccp I′） and（2） the medium–low-temperature stage： sphalerite → fine-grained chalcopyrite（Ccp II′） ＋ chalcopyrite inclusions（Ccp II′） → silica-cemented pyrite（Py II′） ＋ marcasite → Fe-oxide ＋ amorphous silica. We suggest that the fine-grained chalcopyrite inclusions in sphalerite from Longqi and Duanqiao were formed by co-precipitation and replacement mechanisms, respectively. Primary sphalerites from both fields are enriched in Fe（avg. 5.84 wt% for the Longqi field vs. avg. 3.69 wt% for the Duanqiao field）, Co（avg. 185.56 ppm for the Longqi field vs. 160.53 ppm for the Duanqiao field）, and Cd（avg. 1950 ppm for the Longqi field vs. avg. 525.26 ppm for the Duanqiao field）. Cu contents in pyrite from the Duanqiao field（Py I′： avg. 849.23 ppm and Py II′： avg. 1191.11 ppm） tend to be higher than those from the Longqi field（Py I： avg. 26.67 ppm, Py II： avg. 445 ppm, and Py III： avg. 179.29 ppm）. Chalcopyrite from both fields is enriched in Zn（Ccp I： avg. 3226.67 ppm, Ccp II： avg. 9280 ppm, Ccp I′： avg. 848 ppm, Ccp II′（inclusions）： avg. 1098 ppm, and Ccp II′（fine-grained）： avg. 1795 ppm）. The varying contents of Zn in the different pyrite and chalcopyrite generations may result from the zone refining process. An integrated study of the mineralogy and mineralogical chemistry suggests that the hydrothermal fluids of the Longqi area are likely conditioned with higher temperatures and relatively lower fO2 and fS2 than those of the Duanqiao area, but in contrast to the former, the latter is much affected by the compositions of the surrounding rocks.

一种基于核ridge回归的解耦控制系统

提出了一种新的基于核ridge回归的解耦方法.该方法具有传统径向基(RBF)神经网络解耦方法对被控对象数学模型依赖性小的特点,同时又能有效地克服RBF神经网络解耦方法对训练样本要求高、噪声敏感和解耦速度慢的缺点,经核ridge解耦器补偿后的控制系统具有被调节量和调节量之间耦合作用小、动态特性好、稳定性强的优点.补偿后的控制系统具有很强的校正能力,对外界各种干扰也有较强的解耦效果和控制质量.仿真试验表明,采用核ridge解耦器的多变量控制系统能够有效地解除系统各变量之间的耦合作用,且结构简单、易于实现,大大增强了解耦控制系统的实用性能.

A study of impact of the reclamation and artificial island projects on tidal currents and sediment concentration in radial sand ridge field of the South Yellow Sea

The two-dimensional hydrodynamic model, MIKE21, is applied to simulate the tidal currents and sediment concentration in the radial sand ridges of the South Yellow Sea. Results are in accordance with in situ observations. Then the variations of tidal currents and suspended sediment concentration caused by reclamation and artificial islands projects are simulated. The results show that the impacts are limited around the project areas. After the projects, the fan-shaped, Jianggang centered tidal current pattern would be replaced by a pattern which is formed by two tidal paths. One locates at the Xiyang channel in north-south direction, and the other locates at the Huangshayang channel in east-west direction. The reclamation of Tiaozini separates the waters into south portion and north portion. The changes of sediment concentrations coincide with those of currents. Both the sediment concentrations and tidal currents increase at the northwest of Dongsha and the south of Gaoni, while both decrease at the north and south of Tiaozini, and the east and southwest of Dongsha.

Ridge Waveguide Electro-Optic Polymer Modulator with a New Kind of Corona Poled Crosslinkable Polyurethane

A polymer electro optic modulator has been fabricated with the functional layer acting as a kind of corona poled crosslinkable polyurethane. The three optical layers, namely waveguide, photolithography and oxygen are fabricated by spin coating. With the Reactive Ion Etching method, the ridge of the waveguide is constructed. With light at 1 31μm being fiber coupled to waveguide, the mode and the modulation properties of these devices are demonstrated in a micron control system.

Ridge Polynomial神经网络带动量项异步梯度算法的收敛性

将动量项引入到Ridge Polynomial神经网络异步梯度训练算法的误差函数中,有效地改善了算法的收敛效率,并从理论上分析了Ridge Polynomial神经网络的带动量项的异步梯度算法的收敛性,给出了算法的单调性和收敛性(包括强收敛性和弱收敛性)。算法的这些收敛性质对于如何选取学习率和初始权值来进行高效的网络训练是非常重要的。最后通过计算机仿真实验验证了带动量项的异步梯度算法的高效性和理论分析的正确性。

加拿大Hawk Ridge铜镍成矿带Pd-Pt-Au元素地球化学特征及其指示意义

通过收集整理Hawk Ridge成矿带Faclo7,HA,Gamma,Pio Lake等铜镍硫化物矿床的岩心样品分析数据(Cu,Ni,S,Pd,Pt,Au元素),针对不同岩石类型、矿石类型,进行了Pd,Pt,Au元素地球化学特征分析。(Pd+Pt),Pd/Pt等特征值研究结果表明,Pd,Pt元素与成矿岩体的镁铁质程度、硫化物含量关系密切,而与岩浆后期含矿热液作用关系不大。其中,Pd元素在含矿岩浆中溶解度更高,分异程度更高。Pt/(Pt+Pd)比值和Pt/(Pt+Pd)与Cu/(Cu+Ni)关系图解表明,该成矿带铜镍矿属于与溢流玄武岩有关的铜镍矿床。Au元素地球化学特征表明,Au元素表现出强烈的亲铜属性,受Ni,S元素影响较小,主要受岩浆后期含矿热液叠加作用控制。根据Pd,Pt,Au元素与Cu,Ni,S元素相关性可知,区内浸染状矿石、围岩裂隙内块状铜镍矿石、岩体底部块状铜镍矿石、块状铜矿石,表现出不同的Pd,Pt,Au元素地球化学特征,反映了它们是不同成矿阶段形成的产物。

On the Growth and Physiological Characteristics of Rice under Smashing Ridge Tillage

Two-line super hybrid rice （Oryza sativa L.） Guiliangyou 2 was taken as the experimental variety, the growth and physiological characteristics of rice under conventional tillage and smashing ridge tillage were compared based on field re- search. The results showed that smashing ridge tillage was beneficial to the tillering growth of rice plants in the the middle and later periods of tillering; under the tillage mode, the white root was more, the vigour was strong during the whole growing period, the SPAD was extremely significantly higher than that of conventional tillage, the net photosynthetic rate of the leaves was high and held green long, which were beneficial to the production and accumulation of photoassimilates; during mature pe- riod, the dry matter accumulation of the overground part under smashing ridge tillage was significantly higher than that of conventional tillage, and the number of productive ears under smashing ridge tillage was more than that of conventional tillage by 27.6×10^4/hm2, thus, the yield-increasing effect was significant and in- creased by 20.36%.

Study on Relative Soil and Water Conservation Benefits of Ridge Tillage in Different Terrain Conditions in the Black Soil Area of Northeast China

Ridge tillage, which is a very common and important tillage measure in the black soil area of northeast China, has some soil and water conservation bene- fits, but has little attention. It is very important to explore the spatial distribution of the ridge direction of the arable land and its soil and water conservation benefits in different terrain conditions in the black soil area. So Binxian County of Heilongjiang Province was selected as the study area, and 168 field investigation units were ex- tracted by stratified sampling method and investigated. According to equations of slope gradient factor and slope gradient in ridge direction, and based on the soft- ware of Arcmap, SPSS and Excel, the investigation data of soil and water loss in Binxian County were analyzed and counted, The results show that in plain, hilly and mountainous areas, the average ground slope gradients are 1.92°, 6.20° and 8.27° respectively, and the average slope gradients along ridge direction are 1.33°, 4.52°and 6.45° respectively, which account for about 70%, 73% and 78% of the average ground slope gradients in the same terrain condition; the relative quantities of soil erosion in the present ridge tillage condition account for about 55%, 69% and 67% respectively of that in down-slope ridge tillage conditions, so the present ridge tillage has obviously relative soil and water conservation benefits. Based on these results, the reasons of the present ridge tillage status were analyzed, and some reform measures were proposed. The results could not only help to comprehend the spatial distribution and soil and water conservation benefits of ridge tillage in the black soil area of Northeast China, but also provide scientific references for the layout of local soil and water conservation measures.

Light Simplified Cultivation Techniques of Wide Row and Double Ridge with Filming, Fertilizing and Sowing on One for Foxtail Millet

In view of the problems of completely depending on rain, low and unstable yield and complicated planting of dry land foxtail millet, the light simplified cultivation techniques of wide row and double ridge with filming, fertilizing and sowing on one for foxtail millet was formed through the integration of plastic film mulching technology and mechanized production technology by Institute of Millet crops of Hebei Academy of Agriculture and Forestry Sciences, and the techniques were introduced from the key technologies of pre-sowing preparation, sowing, supporting equipment, field management, harvesting, plastic film recycling.

Sedimentary Environment Analysis of Ancient Sand Ridges from Zk23 Hole in the East China Sea

Abstract： Based on the analysis of core samples from the hole of Zk23 in the East China Sea Continental Shelf and by means of sedimentary stratigraphy, biostratigraphy and chronostratigraphy, the authors consider that the fine-sand deposition in borehole was part of buried ancient estuary sand ridges of the Yangtze River. The deposition history of study area around the hole before and after the glacial period as well as postglacial period is made clear after our research： （1） the estuarine sublayer -undersea delta facies strata was deposited under the fast sea level rise about 15 kaB.P; （2） sand ridges mostly consisting of fine-sand, were formed when the sea level was the fluctuant range of 60 - 80 m of isoba during the deglacial period around 15 - 12 kaB.P; （3） first silty clay and clay silt strata above the sand ridges were deposited during the period when the sea level rose fast from 12 to 7 kaB.P, and then it keeps stable to the present.