On Continent-Continent Point-Collision and Ultrahigh-Pressure Metamorphism

Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisphere. UHP metamorphic rocks are represented by coesite- and diamond-bearing eclogites and eclogite facies metamorphic rocks formed at 650-800℃ and 2.6-3.5 GPa, and most of the protoliths of UHP rocks are volcanic-sedimentary sequences of continental crust. From these it may be deduced that deep subduction of continental crust may have occurred. However, UHP rocks are exposed on the surface or occur near the surface now, which implies that they have been exhumed from great depths. The mechanism of deep subduction of continental crust and subsequent exhumation has been a hot topic of the research on continental dynamics, but there are divergent views. The focus of the dispute is how deep continental crust is subducted so that UHP rocks can be formed and what mechanism causes it to be subducted to great depths and again exhumed to the shallow surface. Through an analysis of the continental process and mechanical boundary conditions of the Dabie collisional belt-an UHP metamorphic belt where the largest area of UHP rocks in the world is exposed, this paper discusses the variations of viscous stresses and average pressure in the viscous fluid caused by tectonism with rock physical properties and the contribution of the tectonic stresses to production of UHP. Calculation indicates that the anomalous stress state on the irregular boundary of a continental block may give rise to stress concentration and accumulation at local places (where the compressional stress may be 5-9 times higher than those in their surroundings). The tectonic stresses may account for 20-35% of the total UHP. So we may infer that the HP (nigh-pressure)-UHP rocks in the Dabie Mountains were formed at depths of 60-80 km. Thus the authors propose a new genetic model of UHP rocks-the point-collision model. This model conforms to the basic principles of the mechanics and also to the geologic records and process in the Dabie orogenic belt. It can explain why UHP rocks do nol exist along the entire length of the collisional orogen but occur in some particular positions. The authors also propose that the eastern and western corners of the Himalaya collision zone are typical point-collision areas and that almost all UHP metamorphism of continental crustal rocks occurred in the two particular positions.

The Dynamic Impact of Ocean on Continent

Around 71% of the Earth’s surface is covered by oceans with depths that exceed several kilometers, while continents are geographically enclosed by these vast bodies of water. The principle of fluid mechanics stipulates that water yields pressure everywhere in the container that holds it, and the water pressure against the wall of container generates force. Ocean basins are naturally gigantic containers of water, in which continents form the walls of the containers. In this study, we present that the ocean water pressure against the walls of continents generates enormous force, and determine the distribution of this force around continents and estimate its amplitude to be of the order of 1017 N per kilometer of continent width. Our modelling suggests that the stresses yielded by this force are mostly concentrated on the upper part of the continental crust, and their magnitudes reach up to 2.0 - 6.0 MPa. Our results suggest that the force may have significantly impacted the dynamics of continent (lithospheric plate) and its evolution.

The Continental Scale USMTArray:Lessons Learned and Synergies with SinoProbe-Ⅱ

The USMTArray was completed on June 27,2024,comprising a network of 1779 transportable long-period magnetotelluric(MT)stations(Fig.1)with nominal 70-km grid spacing spanning the conterminous United States,an area of 8.1×10^(6)km^(2).Each station operated for weeksto-months,as required to meet data quality standards over the period band of 10–10000 s.The USMTArray shares similarities with the planned SinoProbe-II MT Array,with its 1-degree station spacing(~111 km in the latitudinal direction)spanning an area of 9.6×10^(6)km^(2).

Distinct Interannual Variability and Physical Mechanisms of Snowfall Frequency over the Eurasian Continent during Autumn and Winter

This study investigates the dominant modes of interannual variability of snowfall frequency over the Eurasian continent during autumn and winter,and explores the underlying physical mechanisms.The first EOF mode(EOF1)of snowfall frequency during autumn is mainly characterized by positive anomalies over the Central Siberian Plateau(CSP)and Europe,with opposite anomalies over Central Asia(CA).EOF1 during winter is characterized by positive anomalies in Siberia and negative anomalies in Europe and East Asia(EA).During autumn,EOF1 is associated with the anomalous sea ice in the Kara–Laptev seas(KLS)and sea surface temperature(SST)over the North Atlantic.Increased sea ice in the KLS may cause an increase in the meridional air temperature gradient,resulting in increased synoptic-scale wave activity,thereby inducing increased snowfall frequency over Europe and the CSP.Anomalous increases of both sea ice in the KLS and SST in the North Atlantic may stimulate downstream propagation of Rossby waves and induce an anomalous high in CA corresponding to decreased snowfall frequency.In contrast,EOF1 is mainly affected by the anomalous atmospheric circulation during winter.In the positive phase of the North Atlantic Oscillation(NAO),an anomalous deep cold low(warm high)occurs over Siberia(Europe)leading to increased(decreased)snowfall frequency over Siberia(Europe).The synoptic-scale wave activity excited by the positive NAO can induce downstream Rossby wave propagation and contribute to an anomalous high and descending motion over EA,which may inhibit snowfall.The NAO in winter may be modulated by the Indian Ocean dipole and sea ice in the Barents-Kara-Laptev Seas in autumn.

Summarizing the evidence for robotic-assisted bladder neck reconstruction: Systematic review of patency and incontinence outcomes

Objective:Bladder neck contracture and vesicourethral anastomotic stenosis are difficult to manage endoscopically,and open repair is associated with high rates of incontinence.In recent years,there have been increasing reports of robotic-assisted bladder neck reconstruction in the literature.However,existing studies are small,heterogeneous case series.The objective of this study was to perform a systematic review of robotic-assisted bladder neck reconstruction to better evaluate patency and incontinence outcomes.Methods:We performed a systematic review of PubMed from first available date to May 2023 for all studies evaluating robotic-assisted reconstructive surgery of the bladder neck in adult men.Articles in non-English,author replies,editorials,pediatric-based studies,and reviews were excluded.Outcomes of interest were patency and incontinence rates,which were pooled when appropriate.Results:After identifying 158 articles on initial search,we included only ten studies that fit all aforementioned criteria for robotic-assisted bladder neck reconstruction.All were case series published from March 2018 to March 2022 ranging from six to 32 men,with the median follow-up of 5e23 months.A total of 119 patients were included in our analysis.A variety of etiologies and surgical techniques were described.Patency rates ranged from 50%to 100%,and pooled patency was 80%(95/119).De novo incontinence rates ranged from 0%to 33%,and pooled incontinence was 17%(8/47).Our findings were limited by small sample sizes,relatively short follow-ups,and heterogeneity between studies.

The Introduction of the Idea of the Hypothetical Magellanica Continent into China during the Seventeenth Century

The idea of the hypothetical Magellanica Continent(Terra Australis Incognita)was introduced into China by the Jesuit missionaries during the seventeenth century.While not accepted by the Chinese government,it was affirmed and transmitted to the public by a few Chinese scholars,including Feng Yingjing,Cheng Bai'er,Zhang Huang,Xiong Mingyu,Xiong Renlin,You Yi,Zhou Yuqi,Jie Xuan,Wang Honghan,and Ye Zipei.Most of them communicated closely with the Jesuit missionaries,and several even helped the missionaries compose the maps.The concept was updated progressively by Matteo Ricci,Giulio Aleni,Johann Adam Schall von Bell,Francesco Sambiasi,and Ferdinand Verbiest.Chinese scholars copied the missionaries'relevant maps and textual introductions without much modification.However,they paid little attention to advancements in the idea,and many of them circulated outdated knowledge.It was not until the middle-and late-nineteenth century that Chinese scholars reexamined the correctness of this hypothetical continent.

Application of Thermodynamic Database to Corrosion of ZrO_(2) Containing Submerged Entry Nozzle in Steel Continuous Casting Process

The CALPHAD thermodynamic databases are very useful to analyze the complex chemical reactions happening in high temperature material process.The FactSage thermodynamic database can be used to calculate complex phase diagrams and equilibrium phases involving refractories in industrial process.In this study,the FactSage thermodynamic database relevant to ZrO_(2)-based refractories was reviewed and the application of the database to understanding the corrosion of continuous casting nozzle refractories in steelmaking was presented.

Impacts of monsoon break events in the western North Pacific on the cross-equatorial flows over the Maritime Continent

本文利用ERA5逐日再分析资料,探讨了1979-2020年间西北太平洋季风中断事件对海洋性大陆越赤道气流的影响.合成结果表明,西北太平洋季风中断事件会造成高,低空越赤道气流减弱,即高层南风异常,低层北风异常,与此相关的环流异常表现为西北太平洋高层气旋,低层反气旋的斜压结构。特别的是,西北太平洋季风中断对高空越赤道气流的影响更为显著,92%的季风中断事件都导致高空越赤道气流减弱,而只有70%的事件造成低空越赤道气流减弱,这是由于低空越赤道气流同时还受到赤道中东太平洋海温异常的调控.

High-temperature granulites and supercontinents

The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature（P-T）conditions of（ultra） high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones（high-pressure metamorphic setting）, and vertically by accumulation of mantle-derived magmas at the base of the crust（high-temperature metamorphic setting）. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions（brines）. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust.This accumulation causes tectonic instability, which together with the heat input from the subcontinental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

Hadean Earth and primordial continents:The cradle of prebiotic life

The Hadean history of Earth is shrouded in mystery and it is considered that the planet was born dry with no water or atmosphere.The Earth-Moon system had many features in common during the birth stage.Solidification of the dry magma ocean at 4.53 Ga generated primordial continents with komatiite.We speculate that the upper crust was composed of fractionated gabbros and the middle felsic crust by anorthosite at ca.21 km depth boundary,underlain by meta-anorthosite（grossular ＋ kyanite 4 quartz）down to 50-60 km in depth.The thickness of the mafic KREEP basalt in the lower crust,separating it from the underlying upper mantle is not well-constrained and might have been up to ca.100-200 km depending on the degree of fractionation and gravitational stability versus surrounding mantle density.The primordial continents must have been composed of the final residue of dry magma ocean and enriched in several critical elements including Ca,Mg,Fe,Mn,P,K,and Cl which were exposed on the surface of the dry Earth.Around 190 million years after the solidification of the magma ocean, ＂ABEL bombardment＂ delivered volatiles including H_2O,CO_2,N_2 as well as silicate components through the addition of icy asteroids.This event continued for 200 Myr with subordinate bombardments until 3.9 Ga,preparing the Earth for the prebiotic chemical evolution and as the cradle of first life.Due to vigorous convection arising from high mantle potential temperatures,the primordial continents disintegrated and were dragged down to the deep mantle,marking the onset of Hadean plate tectonics.

Why run 16 research and development centers in 3 continents? Wouldn't one do?

We keep about 16,000 engineers on the ground across three continents to hear and understand your customers’ demands.

CHIC'98──A Rainbow Linking Garment Markets in Five Continents

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Renewable and Green Energy, Africa’s Pathway to Sustainable Development;Harnessing the Continent’s Natural Energy Sources

Renewable energy includes all forms of energy produced from renewable sources in a sustainable manner, including bioenergy, geothermal energy, hydropower, ocean energy, solar energy, and wind energy. Less than one quarter of Africa’s renewable power generation potential is utilized. Africa’s natural endowments are enormous, yet the continent experiences high energy shortage. Amongst the classifications of energy sources, renewable and green energy sources are increasingly gaining popularity due to their sustainable nature and environmental concerns. This paper explores the continent’s natural energy sources and identifies pathways to sustainable development. The paper also narrows the renewable and green energy sources obtainable on the continent and presents their contribution to the development of the continent. The awareness level of Africans towards renewable energy is discussed and the challenges of renewable and green energy sources are highlighted. Finally, the roles to be played by the government and private organizations in the development of renewable and green energy sources in Africa are discussed.

A Tale of Two Continents

WEI Jianguo is a familiar name in Africa. A star in the con- temporary history of Chinese-African relations, Wei＇s experience is notable in many ways. He has worked in the field for 40 years, which marks the longest tenure among his peers.

基于布迪厄理论的村落体育扶贫工程农民参与意愿研究

采用问卷调查、专家访谈、数理统计等方法,基于布迪厄理论审视“三区三州”村落农民参与体育扶贫工程的意愿。结果表明:人口特征、经济资本、文化资本、社会资本等变量对“三区三州”村落农民参与体育扶贫工程意愿均有不同程度的影响。在性别上,男性较之女性意愿更强;在年龄上,老年人意愿强于青年人,青年人意愿强于中年人;在户口性质上,非农户口意愿强于农业户口。从影响系数看,各因素影响力依次是体育消费情况、农村体育公共服务组织、农村体育参与、家庭经济情况、常住人口,三类资本的影响力均超过人口学特征变量。据此提出建议:刺激农村体育消费、健全农村组织网络、创新农民健身活动、防止农村人口流失。

东昆仑志留纪火山岩锆石U-Pb年龄及其对陆-陆碰撞时限的制约

东昆仑造山带早古生代经历了完整的洋壳形成、俯冲消减、陆-陆碰撞造山和造山后垮塌演变过程,目前对陆-陆初始碰撞时间及碰撞时限还存在较大争议。周缘前陆盆地启动引发的沉积环境突变或不整合形成时间是用来约束大陆初始碰撞时间最直接和最有效的方法之一。本文以东昆仑水泥厂地区角度不整合覆盖于石灰厂组之上的志留纪周缘前陆盆地沉积哈拉巴依沟组为研究对象,开展火山岩夹层锆石U-Pb年代学研究,为约束早古生代陆-陆初始碰撞时间与碰撞造山时限提供沉积记录证据。结果表明,水泥厂东和雪水河东哈拉巴依沟组下部流纹质凝灰岩锆石U-Pb年龄分别为443.0±3.9 Ma和441.8±1.3 Ma,结合已报道的石灰厂组火山岩锆石U-Pb年龄(450.4±4.3 Ma),可以确定东昆仑陆-陆初始碰撞发生在450~443 Ma之间。综合区域上古生代岩浆活动、变质作用、构造变形与相关沉积记录证据,认为东昆仑地区至少从450 Ma左右开始进入陆壳深俯冲及陆-陆碰撞阶段,在425 Ma左右进入碰撞后伸展阶段,碰撞造山作用至少持续了25 Ma。

白乃庙-吉中造山带东段早古生代地层的识别及其地质意义

白乃庙-吉中造山带中的诸多前寒武纪地体是否属于同一个微陆块一直存在着争议,由此制约了对该造山带前寒武纪构造演化及其中微陆块基底构造亲缘性的认识。对造山带东段吉林南部头道沟组的野外观察及锆石U-Pb年代学研究表明,该地层形成时代为631~460Ma,是长春-延吉蛇绿混杂岩带的重要组成部分;白乃庙-吉中造山带东、西两段前寒武纪碎屑锆石年龄谱系和εHf(t)值均具有很好的相似性,同时造山带不同地区岩浆岩的锆石Hf同位素模式年龄和全岩Nd同位素年龄均具有很好的对应性,表明卷入该造山带的前寒武纪地体曾同属于一个微陆块;白乃庙-吉中造山带内的下古生界中存在大量泛非期碎屑锆石(~600Ma),结合造山带与冈瓦纳大陆的前寒武纪碎屑锆石年龄谱系和εHf(t)值的高度吻合性,我们认为该造山带中的微陆块可能来自于冈瓦纳大陆,但其在冈瓦纳大陆中的位置与中亚造山带东段的其他地块(额尔古纳、兴安及布列亚-佳木斯-兴凯地块)相距较远。

粤东连平—河源—汕尾地震测深剖面地壳速度结构及其意义

为适应防灾减灾工作的需要,广东省地震局联合中国地震局地球物理勘探中心、河南省地球物理空间信息研究院于2021年在粤东地区实施了人工地震宽角反射/折射探测,以期获得粤东地区深部地壳速度结构.本文采用地震射线走时正演对粤东地区NW向连平—河源—海丰测线数据进行了处理解释,构建了该剖面的二维壳幔速度结构模型.该模型表明,沿剖面自NW向SE,莫霍面深度由32 km缓慢抬升至29 km,广州—恩平断裂带、河源—邵武断裂带和政和—大埔断裂带的对应位置都显示莫霍面有抬升现象;研究区存在多条NE向展布深大断裂;中地壳发育低速异常区域(低速体)受断裂控制,主要分布于政和—大埔断裂带NW内陆方向,可能与中生代早期岩浆活动形成的花岗岩质岩浆相关.我们认为壳内低速区域(低速体)可能是影响研究区深部孕震环境的重要因素.

造口伤口失禁专科护士开展“互联网+护理服务”制约因素的质性研究

目的通过半结构式访谈探究造口伤口失禁专科护士开展“互联网+护理服务”的制约因素,以期促进相关服务的深入落实。方法2022年2-4月,选取11名山东省造口伤口失禁专科护士为研究对象,围绕“互联网+护理服务”中存在的问题及制约因素,对其进行半结构式访谈,基于扎根理论及Colaizzi七步法对访谈材料进行编码、提取。结果根据访谈结果提炼出造口伤口失禁专科护士开展“互联网+护理服务”的五方面制约因素,分别为:支持保障政策不完善,护患双方存在风险;时间成本较高,专科护士角色冲突;服务定价及医疗费用支付体系有待完善;老年患者互联网服务使用能力弱,平台建设亟待加强;医用耗材及医疗废物处理等物联网支持系统不成熟。结论相关部门需关注“互联网+护理服务”中的医疗安全及护理人员自身安全,通过建立健全相关政策制度、培养专业的护理服务队伍、搭建并完善服务平台和物联网体系、优化服务收费及医保政策等措施,进一步促进造口伤口失禁专业“互联网+护理服务”的良性发展,更好满足患者居家护理需求。

亚洲大陆矿产资源禀赋、矿业开发格局及合作前景展望

亚洲是世界七大洲中面积最大、人口最多、经济发展较快和矿产资源非常丰富的大洲,这些特点也使其矿产资源和矿业开发在世界占有重要的地位。研究表明:(1)亚洲是全球矿产资源种类最齐全的大洲,世界上已发现的矿产资源在亚洲几乎均有分布;(2)亚洲主要矿产的储量世界地位显著增强,在世界广泛应用的80多种常见矿产中,亚洲至少有38种矿产的储量世界占比超过30%;(3)亚洲矿产的储量分布具有“区域性集中分布、集中分布于少数国家、集中受控于少数矿业公司”的“三集中”特征;(4)亚洲大陆是全球成矿条件最复杂、世界级巨型成矿域/大型成矿带富集度最高的大洲,成矿专属性明显,成矿期次大致可划分为前寒武纪、古生代和中—新生代3大期次;(5)亚洲国家“以矿养国”趋势愈发凸显;(6)矿产勘查呈“铜、金当家,大型矿业公司、大国买单”格局;(7)亚洲是世界矿产的生产中心、消费中心、贸易中心和矿业经济中心共4个中心;(8)中国是亚洲矿产的生产中心、消费中心、贸易中心和矿业经济中心4个中心。未来,中国与亚洲其他国家的矿业合作前景广阔。