Differential response of radial growth and δ^(13)C in Qinghai spruce(Picea crassifolia) to climate change on the southern and northern slopes of the Qilian Mountains in Northwest China

Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.

Present-day movement characteristics of the Qinghai Nanshan fault and its surrounding area from GPS observation

The Qinghai Nanshan fault is a larger fault in the Northeastern Xizang Plateau.In previous studies,its movement characteristics are mainly investigated with geological and seismic observations,and the tectonic transformation role of the fault on its east is not yet clear.This study uses data fusion to obtain denser GPS observations near the Qinghai Nanshan fault.Based on tectonic characteristics,we establish a block model to investigate the fault slip rate,locking degree,and slip deficit.The results show that the Qinghai Nanshan fault slip rate is characterized by sinistral and convergent movement.Both the sinistral and convergent rates display a decreasing trend from west to east.The locking degree and slip deficit are higher in the western segment(with an average of about 0.74 and 1.1 mm/a)and lower in the eastern segment.Then,we construct a strain rate field using GPS observations to analyze the regional strain characteristics.The results indicate that along the fault,the western segment shows a larger shear strain rate and negative dilation rate.Regional earthquake records show that the frequency of earthquakes is lower near the fault.The joint results suggest that the western segment may have a higher earthquake risk.In addition,the insignificant fault slip rate in the eastern segment may indicate that it does not participate in the tectonic transformation among the Riyueshan,Lajishan,and West Qinling faults.

Quantification of the concrete freeze–thaw environment across the Qinghai–Tibet Plateau based on machine learning algorithms

The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering managers should take into account. In this paper, we propose a more realistic method to calculate the number of concrete freeze–thaw cycles(NFTCs) on the QTP. The calculated results show that the NFTCs increase as the altitude of the meteorological station increases with the average NFTCs being 208.7. Four machine learning methods, i.e., the random forest(RF) model, generalized boosting method(GBM), generalized linear model(GLM), and generalized additive model(GAM), are used to fit the NFTCs. The root mean square error(RMSE) values of the RF, GBM, GLM, and GAM are 32.3, 4.3, 247.9, and 161.3, respectively. The R^(2) values of the RF, GBM, GLM, and GAM are 0.93, 0.99, 0.48, and 0.66, respectively. The GBM method performs the best compared to the other three methods, which was shown by the results of RMSE and R^(2) values. The quantitative results from the GBM method indicate that the lowest, medium, and highest NFTC values are distributed in the northern, central, and southern parts of the QTP, respectively. The annual NFTCs in the QTP region are mainly concentrated at 160 and above, and the average NFTCs is 200 across the QTP. Our results can provide scientific guidance and a theoretical basis for the freezing resistance design of concrete in various projects on the QTP.

Origin of the Dashuigou independent tellurium deposit at Qinghai–Xizang Plateau: constraints from the light stable isotopes C, O, and H

By studying the light isotopic compositions of carbon,oxygen,and hydrogen,combined with previous research results on the ore-forming source of the deposit,the authors try to uncover its metallogenic origin.The δ^(18)O and δ^(13)C isotope signatures of dolomite samples vary between 10.2 and 13.0‰,and between−7.2 and−5.2‰,respectively,implying that the carbon derives from the upper mantle.δD and δ^(18) O of quartz,biotite,and muscovite from diff erent ore veins of the deposit vary between−82 and−59‰,and between 11.6 and 12.4‰,respectively,implying that the metallogenic solutions are mainly magmatic.According to the relevant research results of many isotope geologists,the fractionation degree of hydrogen isotopes increases as the depth to the Earth’s core increases,and the more diff erentiated the hydrogen isotopes are,the lower their values will be.In other words,mantle-derived solutions can have extremely low hydrogen isotope values.This means that the δD‰ value−134 of the pyrrhotite sample numbered SD-34 in this article may indicate mantle-derived oreforming fl uid of the deposit.The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma.

Spatial-temporal heterogeneity of ecological quality changes across the Qinghai-Tibet Plateau under the influence of climate factors and human activities

Over the last few decades,the ecological quality of the Qinghai–Tibet Plateau(QTP)has significantly changed due to climate warming,humidification,and increasing human activities.Thus,evaluating this region's ecological quality and dominant factors is crucial for sustainable development.In this study,the changes in the ecological quality on the QTP from 2000 to 2020 were evaluated based on aggregated indices and Sen–MK trend analyses,and the dominant factors affecting the ecological quality of the QTP were quantitatively analyzed using decision tree classification.The results revealed that(1)the ecological quality of the QTP exhibited an overall high trend in the east and a low pattern in the west;(2)the ecological quality of the QTP significantly increased from 2000 to 2020,and human activities were the dominant factors causing this change;and(3)the changes in the ecological quality and dominant factors exhibited obvious spatiotemporal heterogeneity.The area with an improved ecological quality occurred mainly in the northern QTP region.It was governed by human activities and precipitation.In contrast,the area with a deteriorated ecological quality occurred largely in the southern QTP region and was dominated by human activities and temperature.The 2000–2010 period was the most significant period of heterogeneity regarding of ecological quality and its driving factors.(4)The change in the ecological quality was mainly affected by the synergistic relationship between human activities and climate change in this region,which encompassed multiple dominant factors.This study provides important information on the spatiotemporal heterogeneity of ecological quality change and its dominant factors on the QTP and offers systematic guidance for the planning and implementation of ecological protection projects.

Response of Freezing/Thawing Indexes to the Wetting Trend under Warming Climate Conditions over the Qinghai–Tibetan Plateau during 1961–2010:A Numerical Simulation

Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming and thermal degradation in permafrost or seasonally frozen ground(SFG)has long been recognized.Still,a predictive relationship between historical wetting under warming climate conditions and frozen ground has not yet been well demonstrated,despite the expectation that it will become even more important because precipitation over the QTP has been projected to increase continuously in the near future.This study investigates the response of the thermal regime to historical wetting in both permafrost and SFG areas and examines their relationships separately using the Community Land Surface Model version 4.5.Results show that wetting before the 1990s across the QTP mainly cooled the permafrost body in the arid and semiarid zones,with significant correlation coefficients of 0.60 and 0.48,respectively.Precipitation increased continually at the rate of 6.16 mm decade–1 in the arid zone after the 1990s but had a contrasting warming effect on permafrost through a significant shortening of the thawing duration within the active layer.However,diminished rainfall in the humid zone after the 1990s also significantly extended the thawing duration of SFG.The relationship between the ground thawing index and precipitation was significantly negatively correlated(−0.75).The dual effects of wetting on the thermal dynamics of the QTP are becoming critical because of the projected increases in future precipitation.

Analysis of Outdoor Cultivation of Pepino(Solanum muricatum)in Qinghai Province

[Objectives]This study was conducted to explore the feasibility of planting pepino(Solanum muricatum Ait.)in Qinghai Province,and to understand the cultivation quality and yield in various areas of Qinghai.[Methods]With small fruit type of pepino as the material,four areas in eastern Qinghai were selected to determine the agronomic traits,yield and quality indexes of pepino.[Results]Under the same cultivation conditions,there were some differences in the cultivation status of pepino,but overall,pepino fruit had higher quality.Various physiological indexes were correlated with quality and yield.[Conclusions]This study clarified the specific cultivation situation of pepino in Qinghai Province,and evaluated the quality and yield of pepino,providing strong data support for the promotion and planting of pepino in various regions in the future.

Analysis on the Spatial Agglomeration and Coupling of Socioeconomic Factors in Qinghai Tourism Under the Background of“Belt and Road”

Qinghai is the strategic base and important fulcrum of the Belt and Road Initiative while tourism is a strategic pillar industry in Qinghai Province.Due to its rich tourism resources and unique ecological environment,the integration of tourism in Qinghai into the Belt and Road has attracted great attention of the Asian Development Bank(ADB).With the spatial data of tourism elements POI and the statistical data of 44 counties in Qinghai to analyze the characteristics and influencing factors of the spatial agglomeration of tourism in Qinghai,the paper conducts research on spatial coupling and concludes with the following results:The spatial agglomeration of tourism in Qinghai presents the distribution pattern of“one circle and one belt”;economic density and population density play an important role in the formation of the spatial agglomeration pattern of tourism with some spatial spillovers;Belt and Road has a significant impact on the promotion of tourism agglomeration in Qinghai.The paper suggests that tourism in Qinghai should fully integrate into the Belt and Road,giving full play to the guiding role of Belt and Road in the allocation of social and economic resources,and optimizing the spatial layout.

2023年12月18日甘肃积石山M_(S)6.2地震触发次生灾害快速评估

2023年12月18日甘肃积石山县发生M_(S)6.2地震,该次地震触发官亭盆地中川乡金田泥流灾害,造成严重的破坏和人员伤亡。通过震前、震后的高分辨率卫星影像对比分析,初步判断此次地震没有引发大型同震滑坡与密集砂土液化,但是震前震中区发育的大量大型黄土滑坡和密集液化砂脉是由更老的地震事件触发。金田泥流灾害是物源区高含水量黏性土在强震动条件下沿沟谷发生流动所致,其发生可能与人类的耕作方式(引黄灌区震前冬季灌溉导致浅表土层含水量提高)有关。

两次不同生命史东移高原涡的动力结构与成因分析

利用NCEP再分析资料对2008年6月25-27日和2013年6月4-10日两次东移出高原的高原涡过程进行结构特征和演变机制的诊断分析,探讨两次长、短路径高原涡过程的结构特征和造成不同生命史的影响因子。结果表明:(1)路径短的扎多涡活动过程中,南亚高压呈扁平状,高空急流偏南,高原涡处在下滑槽中移出高原;路径长的曲麻莱涡活动过程中,南亚高压有些北拱,高原涡处在南亚高压脊前西北气流下空,副高偏南,高原涡随低槽东移加强,并伴有西南涡东移。(2)两次高原涡过程结构特征差异明显,主要表现在扎多涡在高原上增强时、曲麻莱涡与西南涡耦合及之后再度加强时的结构特征,前者低涡处在600~350 hPa较深厚的正涡度、上升运动层内,还具有对流层高层强辐散的结构特征;后者具有对流层高、中、低层正涡度贯通、对流层内为上升运动、对流层低层辐合,对流层高层弱辐散的结构特征,其中对流层低层由整个对流层内为最强正涡度,演变为整个对流层内为最强正涡度、最强上升运动、最强辐合。(3)总涡度收支诊断表明,散度项变化对低涡总涡度变率变化起决定性作用。扎多涡的强度变化与散度项变化一致。曲麻莱涡在与西南涡伴行过程中,垂直输送项、水平平流项的影响在加强。(4)涡中心区500 hPa正涡度变率的收支分析看出,高原涡在没有西南涡活动时,对高原涡的500 hPa正涡度变率贡献的主要是涡度辐合造成的;在有西南涡活动时,随着与西南涡垂直方向叠合、伴行,正涡度垂直输送显得更加重要。

青藏高原草地生态系统演化过程、可持续发展瓶颈及应对分析

青藏高原面积巨大,自然条件恶劣,生态环境脆弱,具有生态、生产和生活的三生服务功能。自20世纪80年代以来,在气候变化、人口激增、市场冲击和经营管理模式改变等多种因素影响下,青藏高原草地生产服务功能逐渐被弱化,“人-地”矛盾凸显,如何实现青藏高原草地生态系统的可持续发展成为“关系人民福祉、关乎民族未来的大计”。基于此,本文梳理了青藏高原生态系统演化历史、植被演化过程及不同历史时期人类活动及区域经济-资源发展模式特征,发现:1)在大的时空间尺度下,青藏高原植被演替的主控因子为气候变化和剧烈的地质变迁,在小的时空尺度下,导致相同地理和气候单元植被特征分异的原因是放牧强度的分异,而草地过度放牧的原因同家庭牧场的管理、草地生态价值的可评估性、人口与生产力发展适配度等关系密切。2)规模化放牧在青藏高原区域具有数千年历史,并形成了人-草-畜协同演化的互利共生关系,青藏高原草地生态系统可持续发展需要在汲取当地传统知识和文化精华的基础之上,扩大草地生产的层次性,引入或研发以生产和生态效益共赢为目的的科学技术,完善和延伸草地生产产业链,完善高原生态系统生态价值评估体系,调动牧场管理者草地健康保护的主观能动性,完成草地健康监管奖惩制度,以生产力、管理和文化为调节手段提高青藏高原区域农牧业现代化和商品化程度,实现青藏高原草地生态系统资源可持续利用发展及区域生态文明建设。

青藏高原东坡地形对影响云南降水的高原涡的作用机理

利用常规观测资料、FNL分析资料及经质控后的自动站小时降水数据,诊断分析了青藏高原东坡地形在2017年7月2-3日高原涡影响云南降水过程中的作用,并利用数值模式WRFv4.0对此次过程进行了地形敏感性试验。结果表明:高原涡是此次云南强降水的重要影响系统;低涡中心及附近区域中高层维持暖心结构,并呈现显著的上升、下沉运动交替的分布;过程累积雨量分布表现为两条明显的与山脉走向平行的西北-东南向雨带,且具有强弱交错的分布特征,强降水集中出现在午后至傍晚及前半夜两个时段内,中心均位于地形边坡,并随着低涡向下游传播;南亚高压、西北辐散气流、西太平洋副热带高压及滇缅高压为低涡的东移发展提供了有利的高空环流场,500 hPa正涡度及700 hPa水汽通量辐合中心对强降水落区具有较好指示意义;低涡降水期间存在β中尺度重力波,波动由青藏高原东坡地形激发,沿着300~200 hPa的气层传播,高空的非地转平衡运动及垂直风切变为重力波的发展及传播提供了有利条件,重力波先于低涡及降水向下游方向移动及发展,波脊处对应上升运动及辐散中心,波槽处对应下沉运动及辐合中心,强降水及波脊均位于低涡西南侧强辐合上升运动区;地形高度降低后,其机械阻挡抬升作用减弱,重力波和高原低涡消失,雨带强度及空间分布特征发生显著改变。高原东坡地形对高原涡的形成和发展,以及高原涡影响下的云南降水具有重要作用。

Contribution of external forcing to summer precipitation trends over the Qinghai-Tibet Plateau and Southwest China

在过去的60年中,全球气候经历了快速变暖和短暂的变暖停滞,而中国的区域降水也经历了多样而复杂的变化.本文分析了1961年至2014年外强迫因子对青藏高原和中国西南地区夏季降水趋势的影响.观测数据显示,青藏高原的夏季降水呈增加趋势,而中国西南地区的夏季降水呈减少趋势,这两个相邻地区的夏季降水变化趋势相反.利用CMIP6数据,本文研究了不同外强迫因子对两个区域夏季降水趋势的影响.结果表明,温室气体对青藏高原夏季降水的增加具有显著影响,而气溶胶在中国西南地区夏季降水减少中起主要作用。

青藏高原形成演化动力机制及其远程效应

作为第三极的青藏高原的形成是新生代以来的地球节律构造事件中最典型、最显著的新构造运动的结果,其构造地貌特征及其重要性,内部单元组成,构造演化历程及动力机制,以及对周边盆地乃至整个中国大陆的影响及远程效应至今一直是学术关注的焦点。本文重新圈定了青藏高原构造地貌范围,确立了其在全球构造中的地位。青藏高原的远程效应向南北两侧延伸,北到北冰洋,南到太平洋,总体上围绕东经105°经线穿越了整个亚洲大陆,本文采用东经105°所在经线大圆作为划分东西半球的分界线,该线以东为东半球,以西为西半球。青藏高原处于全球最大、最重要的南北向构造和东西向构造的交汇处,其内部的帕米尔高原更是区域构造的中流砥柱。青藏高原起源于帕米尔高原,它是一个印支期的热穹窿,晚期转化出一条直径200 km的异常重力柱,垂直下沉至600 km,构成一个垂向上的挤压-伸展构造,完成于白垩纪。以它为中心向东西扩展,东边三条、西边一条水平方向挤压-伸展构造。喜山期它还遭受到岩体的侵入,白垩系基本上未变形。古近纪,印度陆块与亚洲陆块碰撞,形成先压后升的雄伟的喜马拉雅造山带。以它为中心向北扩展,第四纪3个地幔枝上升,导致整个青藏高原上升。青藏高原形成与演化的深部动力机制模型:早期表现为地质体在垂向上的离心运动和在水平上的伸展运动;后期是以挤压为主的阶段,表现为地质体在垂向上的向心运动和水平上的挤压运动。从驱动力的角度,早期以热能为主驱动力,后期以重力势能为主驱动力。青藏高原的隆升及其形成演化是欧亚陆块新生代最令人瞩目的地质事件,其直接影响到岩石圈浅部及地壳表层与人类生存发展息息相关的地形地貌、能源、资源、生态、环境和灾害等,产生了具有举足轻重的近区及远程效应。3个远程效应分别是贝加尔湖裂谷、汾渭裂谷以及东非三叉裂谷的形成。本文最后对印支运动的命名和穿时问题、印支运动起止时间和类型、青藏高原是研究各类造山带的最佳基地、喜马拉雅造山带东西构造结的确定和帕米尔高原四维动力学模型的探索等5个问题进行了简单讨论。

2023年甘肃积石山6.2级地震发震构造浅析

2023年12月18日23时59分,甘肃临夏州积石山县发生6.2级地震,造成人员伤亡和财产损失。本次地震发生在青藏高原东北缘地区,受青藏高原向NE向扩展挤压作用的影响,区域发育两组较为典型的断裂构造:NWW向大型左旋走滑断裂带是活动块体运动边界,另一组NNW向右旋走滑断裂则发育在块体内部构成次级块体边界。此次积石山6.2级地震就发生在NWW向西秦岭北缘左旋走滑断裂带和NNW向日月山右旋走滑断裂带之间的大型挤压阶区内,初步判定其发震构造为以逆冲作用为主的拉脊山断裂带东南段的积石山东缘断裂。余震展布范围严格限制在黄河以南的积石山东麓大河家第三系盆地内,根据黄河以北拉脊山和以南的积石山山脊线及坡折带存在较大不连续性,且沿黄河南岸发育较明显的断层三角面等构造地貌特征,推测沿黄河发育有一条调节区内挤压变形差异的横向断裂。断裂切断拉脊山北缘断裂带东南段,使积石山东缘断裂成为一个长度不足40 km的独立活动段,判定原震区近期发生更大地震的可能性不大。

青海湖流域种子植物区系研究

青海湖流域位于青海省东部(36°15′~38°15′N,97°50′~101°45′E),处于青藏高原和黄土高原的过渡地带,海拔3 160~4 953 m,全区面积约29 660 km2,属于高原大陆性气候。该区有种子植物823种,隶属于61科231属,依次为青海种、科、属数的23.13%、62.89%和38.82%。区系分析结果表明:(1)该区系的种类仅有2.78种/km2,这在唐古特地区的众多自然区域中相对并不丰富。(2)包括中国特有植物种类在内,该区系的温带成分占99.00%,以绝对优势确定了本区系明显的温带性质。(3)木本种类少,少有古老的和原始的类群,而是以多年生草本为核心的植物区系。(4)该区的一些中国特有种是经其广布的亲缘种衍生而来,这是该区系年轻和衍生的性质的具体体现。(5)我国华北区系和西南高山区系均对该区具有不同程度的影响。(6)特有属少,特有种多数为水生植物,表现出青海湖独特而隐域性的水湿环境的特化结果。(7)中国特有种的核心成分是出现种类最多的甘肃—西藏—四川亚型。而在青藏高原植物亚区中,该区隶属于其中的唐古特地区。

CMIP6耦合模式对青藏高原积雪的未来预估

基于第六次国际耦合模式比较计划(CMIP6)的历史模拟试验以及情景预估试验数据,分析了21世纪中(2035—2064年)、后期(2070—2099年)青藏高原积雪相对于参考期(1985—2014年)的变化。结果表明:相对于参考期,21世纪中、后期青藏高原平均年积雪日数、平均积雪期均表现为减少,减少幅度总体随着人为辐射强迫的增加而加大;除低强迫情景外,21世纪后期的减少幅度均大于21世纪中期;空间上总体表现为青藏高原东南部的减少幅度大于西北部。21世纪中、后期青藏高原积雪初日均表现为推迟、积雪终日均表现为提前,积雪初日推迟天数是积雪终日提前天数的1.5~2.0倍;人为辐射强迫越高,积雪初(终)日推迟(提前)天数越多;相同情景下21世纪后期积雪初(终)日推迟(提前)天数均多于21世纪中期。降雪(气温)与年积雪日数呈正(负)相关;随着人为辐射强迫的增加,降雪对年积雪日数的相对贡献率总体呈增加趋势;空间特征表现为降雪(气温)对青藏高原南部和北部(东部和西部)的年积雪日数的相对贡献更大。7—12月降雪的减少幅度大于1—6月,这可能是积雪初日推迟天数多于积雪终日提前天数的重要原因。不同情景下青藏高原未来积雪变化差异明显,由此可见,控制温室气体排放对减缓未来青藏高原积雪的减少速率至关重要。

垂穗披碱草根际促生菌的分离鉴定及促生作用研究

优良的根际生长促生菌(Plant growth-promoting rhizobacteria, PGPR)是生产优质微生物菌肥的重要物质基础。本研究以广布于青藏高原的垂穗披碱草(Campeiostachys nutans Griseb.)为材料,采用平板划线法分离其PGPR,探究菌株的促生特性,通过16S测序确定菌株的分类地位,并进行盆栽试验验证PGPR的促生效果。结果表明,从垂穗披碱草根际土筛选出14株促生特性优良的PGPR,其中,有11株兼具产IAA,ACC脱氨酶以及铁载体的能力。经16S rDNA鉴定,以假单胞菌属为优势菌属,6株属于假单胞菌属(Pseudomonas),2株属于芽孢杆菌属(Bacillus),2株属于葡萄球菌属(Staphylococcus),其他四株分别属于类节杆菌属(Paenarthrobacter)、微杆菌属(Microbacterium)、不动杆菌属(Acinetobacter)和考克氏菌属(Kocuria)。盆栽试验表明,接种14株菌株对多年生黑麦草具有良好的促生效果,并能够提高其光合效率。研究结果丰富了植物根际促生菌菌种资源库,为实现农业“绿色增产”提供优质菌肥种质资源。

青藏高原陆陆碰撞-挤出活动构造体系控震作用:以1990年以来强震活动为例

青藏高原是地中海-喜马拉雅地震带上强震活动最频繁的区域之一,深入认识该区的活动构造体系控震效应对于区域强震危险性分析具有重要科学意义。从陆陆碰撞-挤出活动构造体系角度,对青藏高原自1990年以来的MW≥6.0强震活动及控震构造机制进行分析发现,青藏高原陆陆碰撞-挤出构造体系对区域强震活动起到显著控制作用,区域强震事件尤其是MW≥6.5地震主要出现在构造体系的主要边界断裂带上,并显示出相对有规律的时空迁移过程,而且青藏高原东部的多层次挤出-旋转活动构造体系构成了1990年以来强震过程的主要控震构造,其次是喜马拉雅主前缘逆冲断裂带。因此,青藏高原挤出构造体系应是未来强震活动趋势分析最值得关注的区域,尤其是当前最为活跃的巴颜喀拉次级挤出构造单元。对比分析土耳其安纳托利亚板块及周边的强震活动发现,该区具有类似的陆陆碰撞-挤出构造体系及控震效应,表明该构造体系是陆内造山中的一种典型的控震构造。进一步综合分析认为,活动构造体系控震效应的主要表现:一是构造体系中主要断块的边界断裂带通常是强震活动的主要场所;二是构造体系中不同构造带的强震活动常具有联动效应或相互触发关系,其中的复杂或特殊构造部位则是易出现双震或震群活动的场所;三是当构造体系中某个构造单元或构造带处于活跃阶段时,便会出现强震丛集现象。另外,充分认识构造体系中主要活动断层间的协调变形关系,活动断层带上的强震活动的分段破裂行为,以及活动断层上强震原地复发通常存在“周期长、准周期性和丛集性”的特点等,有助于在根据活动构造体系分析区域未来强震活动趋势时更为准确地判定活动断层带的未来强震危险性。

青藏高原盐湖硼、锂同位素变化规律及其对当雄错盐湖资源评价应用

近年,硼、锂同位素地球化学理论和分馏机理的深入,为盐湖体系硼、锂同位素示踪奠定了基础。基于现有大量研究数据,文章系统归纳盐湖体系硼、锂同位素分馏变化特征,总结盐湖演化过程硼、锂同位素组成的变化规律,建立它们的示踪方法。并以此为基础,对西藏典型富硼、锂盐湖−当雄错开展了硼同位素示踪,解决了当雄错与其物源硼同位素特征不符的难题,提出当雄错湖底蕴含大型硼、锂矿床的新认识,并预测了湖底的硼、锂资源量。根据盐湖体系硼、锂同位素地球化学特征,揭示了溶蚀湖的盐湖资源评价意义,为盐湖体系硼、锂同位素示踪和盐湖资源评价奠定理论基础。此外,借助硼同位素地球化学手段建立的当雄错“围岩−地热水−盐湖”的物源补给模式在西藏和全球具有普遍性。