Groundwater irrigation and its implications for water policy in semiarid countries: the Spanish experience

Over the last decades, groundwater irrigation has become commonplace in many arid and semiarid regions worldwide, including Spain. This is largely a consequence of the advances in drilling and pumping technologies, and of the development of Hydrogeology. Compared with traditional surface water irrigation systems, groundwater irrigation offers more reliable supplies, lesser vulnerability to droughts, and ready accessibility for individual users. Economic forces influence the groundwater irrigation sector and its development. In Spain's Mediterranean regions, abstraction costs often amount to a very small fraction of the value of crops. In the inner areas, groundwater irrigation supports a more stable flow of farm income than rainfed agriculture. The social (jobs/m³) and economic (€/m³) value of groundwater irrigation generally exceeds that of surface water irrigation systems. However, poor groundwater management and legal controversies are currently at the base of Spain's social disputes over water. A thorough and transparent assessment of the relative socio-economic value of groundwater in relation to surface water irrigation might contribute to mitigate or avoid potential future conflicts. Enforcement of the European Union's Water Framework Directive may deliver better groundwater governance and a more sustainable use.

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Resumen Durante las últimas décadas, la irrigación con agua subterránea se ha vuelto común en muchas regiones áridas y semiáridas alrededor del mundo, incluyendo a España. Ésta es en gran medida una consecuencia de los adelantos en las tecnologías de perforación y bombeo, y del desarrollo de la Hidrogeología. Comparada con los sistemas tradicionales de irrigación con agua superficial, la irrigación con agua subterránea ofrece suministros más fiables, la vulnerabilidad es menor a las sequías, y posee accesibilidad inmediata para los usuarios individuales. Las fuerzas económicas influyen el sector de irrigación con agua subterránea y su desarrollo. En las regiones mediterráneas de España, los costos de extracción suman a menudo una parte muy pequeña del valor de las cosechas. En las áreas internas, la irrigación con agua subterránea constituye un flujo más estable de ingresos para la granja, que la agricultura dependiente del agua lluvia. El valor social (empleos/m³) y económico (€/m³) de la irrigación con agua subterránea, generalmente excede a aquél con sistemas de irrigación de agua superficial. Sin embargo, la gestión pobre del agua subterránea y las controversias legales están actualmente en la base de las disputas sociales en España acerca del agua. Una evaluación completa y transparente del valor socio-económico relativo de agua subterránea respecto a la irrigación con agua superficial, podría contribuir mitigar o evitar los conflictos potenciales del futuro. La entrada en vigor del Marco Reglamentario de Agua de la Unión Europea, puede conllevar a una administración mejor del agua subterránea y a un uso más sostenible.

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Résumé Depuis les dernières décennies, l’irrigation avec l’eau souterraine est devenue commune dans plusieurs régions arides et semi-arides, incluant l’Espagne. Ceci est largement une conséquence due à l’avancement aux technologies de forages et des pompages, et au développement de l’Hydrogéologie. Comparé avec des systèmes traditionnels d’irrigation utilisant l’eau de surface, l’irrigation avec l’eau souterraine offre une technique d’alimentation plus fiable, une vulnérabilité à la sécheresse moins grande, et une accessibilité plus aisée pour chaque utilisateur. Les forces économiques influencent le secteur de l’irrigation par l’eau souterraine et son développement. Dans les régions de l’Espagne Méditerranéenne, les coûts d’exploitation représentent toujours une petite fraction de la valeur des cultures. Dans les régions intérieures, l’irrigation par l’eau souterraine supporte une agriculture plus stable et continue qu’une agriculture reposant sur l’eau de pluie. La valeur sociale (emploi/m³) et économique (€/m³) de l’irrigation avec l’eau souterraine, excède généralement celle des systèmes d’irrigation avec l’eau de surface. Néanmoins, des gestions pauvres de l’eau souterraine et des controverses légales sont couramment à la base de disputes sociales sur l’eau. Un bilan transparent et minutieux des valeurs relatives socio-économiques de l’eau souterraine en relation avec l’eau de surface d’irrigation, devrait contribuer à éviter de potentiels et futurs conflits. Un renforcement de la Directive Cadre de l’Union Européenne devrait apporter une meilleure gouvernance et un usage plus durable.

     

Geographies of production in 3D: Theoretical and research implications stemming from additive manufacturing

Additive manufacturing (or 3D printing) is a comparatively new and evolving form of production that has the potential to transform the geographies of manufacturing. While this technology has garnered significant hype in the popular media, the topic has been virtually ignored in academic circles outside of business- and industry-specific, technology-oriented journals. Given its prospective impacts on the secondary sector and the potential for geographers to explore these transitions, this article provides a discussion of the possible opportunities for theoretical explorations and research into the place-based facets of additive manufacturing and its impacts on, or integration with, traditional manufacturing. In particular, we examine the spatial ramifications of this technology on supply, demand, innovation, global production networks, and the role of the state juxtaposed against contemporary insights pertaining to advances in additive manufacturing.     

关于茶、稻中铅、氟限量标准的讨论

对浙江省农业地质环境调查有关农产品安全性资料成果,分析在茶、稻中的铅、氟含量水平及安全性,并探讨了影响农产品安全的原因,进行了茶叶和水稻中铅、氟限量标准的讨论,认为国内对食品卫生标准制定趋于偏紧。参照日本、加拿大的茶叶氟元素限量标准,提出浙江省茶、稻的铅、氟元素限量标准。     

古气候演化特征、驱动与反馈及对现代气候变化研究的启示意义

古气候与现代气候变化研究如何有效结合,特别是古气候研究如何为理解现代气候变化过程提供背景条件、边界约束和理论框架,值得深入探讨。文章以现代、历史时期、全新世、晚第四纪和新生代为时间基线,回顾阐述了过去气候演变特征、成因机制及其对现代气候变化研究的启示意义,探讨了过去与现代气候变化融合研究中存在的不确定性。过去气候演化过程的研究,加深了人们对地球气候系统运行机制的理解。研究表明,各个时期中,地球气候经历了不同相位、幅度和速率的变化,气候系统各分量之间发生了复杂的相互作用,以地表温度为代表的地球表面热力环境演化是各不同阶段气候变化的基本表现形式。全球温度变化不仅受到太阳输出辐射、地球轨道参数和地球构造运动等的影响,而且与地球表层水圈中的海洋、冰冻圈中的大陆冰盖、生物圈中的海洋浮游生物和陆地植被,以及大气圈中的温室气体、粉尘气溶胶、水汽和云等活跃组分之间,存在着多尺度复杂反馈作用。在同一时间尺度上,气候系统分量的互馈通路可能是同向的、可比的,各分量之间的对应关系或具有一致性,研究结论对于预估未来气候变化有借鉴意义;但在不同时间尺度上,气候系统各分量之间的相互联系机制可能难有一致性和可比性,古今互鉴,就需要慎重。

     

Aluminous orthopyroxene: Order-disorder,thermodynamic properties,and petrologic implications

Orthopyroxene has two tetrahedral sites, designated A and B, and two octahedral sites, M1 and M2. Crystallographic studies of synthetic and natural orthopyroxenes (opx) suggest that the tetrahedral Al is ordered nearly completely in the B site, but the octahedral Al disorders between M1 and M2 sites with a preference for M1. If the aluminum avoidance principle is obeyed, then the tetrahedral Si-Al ordering limits the Al substitution in opx to 25 mol%, thus leading to an end-member stoichiometry of Mg₃Al₂Si₃O₁₂ instead of MgAl₂SiO₆.The enthalpy of formation of these two components has been deduced from the available phase equilibrium data. The thermodynamic properties of the opx solid solution approximates ideal solution behavior more closely when treated in terms of the components Mg₄Si₄O₁₂(QEn)-Mg₃Al₂Si₃O₁₂(Py) than when expressed in terms of the components Mg₂Si₂O₆-MgAl₂SiO₆. A model has been developed for the octahedral disordering of Al as function of temperature and composition. These data enable calculation of the configurational entropy and molar entropy of Al-opx; distinction has been made between the cases of completely random mixing of Al and Si in the tetrahedral B site, and of random mixing without violation of the aluminum avoidance principle. The second model yields entropy of the Mg₃Al₂Si₃O₁₂ end member which agrees almost exactly with the value derived from phase equilibrium data. The partial molal entropies of the Orthopyroxene components QEn and Py can be derived from these data; their implications with respect to the P-T slopes of Al₂O₃ isopleths for the equilibrium of Orthopyroxene with forsterite and spinel/garnet have been discussed.     

Tectonic implications of paleomagnetic research into Upper Cretaceous magmatic rocks in the Apuseni Mountains, Romania

The paleomagnetism of Upper Cretaceous magmatic rocks from 47 collecting sites (172 samples, 692 specimens) in the Apuseni Mountains was studied. After AF cleaning, characteristic magnetizations were identified for various collecting areas in the study zone, which defined a few spatial and temporal units for which paleomagnetic poles could be derived statistically. At 21 sampling sites the paleomagnetic directions showed a high level of intrasite and intersite consistency, with a mean direction of I_f = −38° and D_f = −100°, with ₉₅ = 6°. The paleomagnetic results show that to reach their present-day position the Apuseni Mountains moved to the north, around 14° with respect to Europe, or around 25° with respect to the geographic poles, between the Campanian and, probably, Late Miocene, while a clockwise rotation, of around 80°, was taking place.     

Controlled moraines: origins,characteristics and palaeoglaciological implications

Controlled moraines are supraglacial debris concentrations that become hummocky moraine upon de-icing and possess clear linearity due to the inheritance of the former pattern of debris-rich folia in the parent ice. Linearity is most striking wherever glacier ice cores still exist but it increasingly deteriorates with progressive melt-out. As a result, moraine linearity has a low preservation potential in deglaciated terrains but hummocky moraine tracts previously interpreted as evidence of areal stagnation may instead record receding polythermal glacier margins in which debris-rich ice was concentrated in frozen toe zones. Recent applications of modern glaciological analogues to palaeoglaciological reconstructions have implied that: (a) controlled moraine development can be ascribed to a specific process (e.g. englacial thrusting or supercooling); and (b) controlled moraine preservation potential is good enough to imply the occurrence of the specific process in former glacier snouts (e.g. ancient polythermal or supercooled snouts). These assumptions are tested using case studies of controlled moraine construction in which a wide range of debris entrainment and debris-rich ice thickening mechanisms are seen to produce the same geomorphic features. Polythermal conditions are crucial to the concentration of supraglacial debris and controlled moraines in glacier snouts via processes that are most effective at the glacier–permafrost interface. End moraines lie on a process–form continuum constrained by basal thermal regime. The morphological expression of englacial structures in controlled moraine ridges is most striking while the moraines retain ice cores, but the final deposits/landforms tend to consist of discontinuous transverse ridges with intervening hummocks, preserving only a weak impression of the former englacial structure. These are arranged in arcuate zones of hummocky moraine up to 2 km wide containing ice-walled lake plains and lying down flow of streamlined landforms produced by warm-based ice. A variety of debris entrainment mechanisms can produce the same geomorphic signature. Spatial and temporal variability in process–form relationships will lead to the sequential development of different types of end moraines during the recession of a glacier or ice sheet margin.     

Local economic development: Theory, evidence, and implications for policy in Brazil

Local economic development policies have surged in Brazil over the past decade—a major shift in this regionally diverse country of 27 states, over 5000 municipalities, and the largest economy in Latin America. We review the stylized facts, expected patterns and policy recommendations from the foundational studies in regional and urban economics. We then provide a summary of a more recent stream of scholarship focused on local economic development (LED) studies in developed and developing countries that have surged in the last 20 years. Based on this review, we then systemize the findings emerging from studies focused on analyzing local economic development policies in Brazil recognizing the distinctive contributions emerging from both the empirical and the case studies literatures. We identify key lessons for (and from) the Brazilian experience and conclude that Brazil and Latin American countries need a new generation of studies that undertake more rigorous evaluations of these policy experiments. Finally, we recommend steps to advance such research.     

Tertiary volcanism in the veneto: Magmatology,petrogenesis and geodynamic implications

The magmatic activity of the Venetian Tertiary Volcanic Province took place between Paleocene and Upper Oligocene. It is characterized mainly by basic and ultrabasic products; only in the Euganean Hills can be found a magmatism predominantly of acidic-type (trachytes and rhyolites) and scarce latites be found. The whole of Venetian volcanism shows a mildly alkaline character, tholeiitic products have flowed only in the latest phases of activity. The possible link between Venetian volcanism and alpine subductive processes have been examined, taking into account the serial features and the structural setting of the region. The close affinity of the Venetian volcanics with those of typical anorogenic series, together with geo-structural considerations, suggest that, very probably, the “alpine orogen” has suplied anomalous geothermal gradients which, in a severe extensive tectonic picture, have caused melting processes in the upper mantle.     

The Omolon pallasite: Chemical composition,mineralogy, and genetic implications

The chemical composition of mineral components of the Omolon pallasite was determined by neutron-activation. Six types of olivines were distinguished. Four types differ in the abundance of Co relative to Ni of CI chondrites. The fifth and sixth types were distinguished on the basis of REE distribution in them. Both last types are variably enriched in LREE relative to CI chondrites. In terms of Ca content relative to CI chondrite, these six types are subdivided into two groups: low-calcium and high-calcium. The difference in Ca contents can be caused by different cooling rate of the precursor of these olivines. The distribution pattern of siderophile elements in the pallasite metal indicates that a metallic phase experienced chemical transformations since the time of its formation. The analysis of chemical composition of accessory minerals showed that: (1) HREE are accumulated in tridymite; (2) troilite and daubreelite were formed under different temperature conditions; (3) magnetite is the mineral of the outer zone of melting crust. Four fragments with anomalous contents of lithophile elements were found in the pallasites and studied. The unusual chemical composition of phases and high degree of HREE fractionation in the fragments suggest their formation at high temperatures at the early stage of the Solar system evolution. It is assumed that the Omolon pallasite was formed as impact-brecciated mixture of the asteroid core (with composition close to IIIAB group of iron meteorites) and mantle olivine from incompletely differentiated parent body of chondrite composition.     

国内外城市生态网络建设经验及对上海的启示

城市基本生态网络的实施是一项艰巨的任务,必须在行政、经济、技术等多方面进行保障,并在政策方面有所创新,才能激发政府、开发商、业主及其他利益相关者等对实施生态空间的积极性。本文搜集和分析了国内外生态城市建设、生态控制线实施等相关案例以及生态补偿机制的研究和实践,提出了对上海市实施生态控制线的建议。     

Low-rhenium molybdenite by metamorphism in northern Sweden: Recognition, genesis, and global implications

Re–Os dating of molybdenite is an accurate means to date intrusions and intrusion-related ore deposits using the model age or isochron approach. But, molybdenite has a new niche in the greenschist- to granulite-facies metamorphic environment. Re–Os ages for metamorphic molybdenite may be used to construct regional metamorphic histories. Age significance and accuracy are established by analyzing multiple molybdenite separates extracted from single, petrographically-characterized molybdenite occurrences. In this study, twelve geologically distinct molybdenite-bearing samples from two small Mo districts in northern Sweden trace a 150 m.y. Paleoproterozoic Svecofennian metamorphic history from 1900 to 1750 Ma. These data reveal a little-known, widespread and protracted, Late Svecofennian anatexis in northern Sweden.The Kåtaberget Mo–(Cu, F) deposit is located in the Moskosel granite batholith north of the economically-renown Skellefte district. Four different molybdenite samples from outcrop at Kåtaberget indicate an intrusion age of 1895 ± 6 Ma with the formation of later pegmatite–aplite at 1875 ± 6 Ma. The Allebuoda (Björntjärn) and Munka Mo–(W) deposits in the Rappen district are represented by three outcrop and five drill core samples of molybdenite-bearing aplite–pegmatite–granite. These two deposits were previously described as intrusion-related Climax-type Mo mineralization. Re–Os ages for molybdenites from these deposits range from 1865 to 1750 Ma and, significantly, Re concentrations are markedly low, extending to the sub-ppm level. Age agreement within the deposits is conspicuously lacking, whereas, with one exception, age agreement within any single sample (geologic occurrence), as established by analysis of additional molybdenite separates, is very good. These data, together with fundamental geologic observations discussed in this paper, suggest that Mo–(W) mineralization in northern Sweden is not intrusion-related, but the local product of episodic melting of Archean–Paleoproterozoic supracrustal gneisses related to the Svecofennian orogeny. Petrographic traverses across the boundary between widespread, foliation-parallel units of aplitic to pegmatitic pink granite and hosting biotite gneiss directly capture the process of ore formation. Dehydration breakdown of zircon-rich biotite aligned with the foliation in the gneiss is accompanied by formation of new pristine, post-deformational biotite plus sulfides, oxides, hydrothermal zircon and fluorite, all associated with microcline-dominant leucosomes.This process has profound implication for the traditional leucogranite, intrusion-related genesis attributed to the broad classification of Mo–W–Sn–base and precious metal mineralization (e.g., South Mountain Batholith, Nova Scotia; Okiep, Namaqualand, South Africa; Mactung, Yukon; Pogo–Liese, Tintina, Alaska; Carajás and Goiás–Rio Tocantins, Brazil; New England Batholith, NSW, Australia; Bergslagen, Sweden; Nevoria, Western Australia; Alpeinerscharte, Austria; Erzgebirge, Germany; Sardinia–Corsica Batholith). In addition to biotite, metallogenic contributions (e.g., Mo, W, Sn, U, Bi, Cu, Pb, Zn, Fe, Ni, Co, Au, Ag, Te, As, Sb, REE) in various combinations may also be controlled by breakdown of amphibole. In effect, the trace element composition of dehydrating or recrystallizing components in a gneissic rock essentially defines the local and district metallogenic suite. In the absence of focusing structures (e.g., shear zones, sheeted vein development), this process will generally form small and disconnected subeconomic deposits with erratic and unpredictable grades. Low Re content in associated molybdenite is a key indicator for a subeconomic origin by local melting of biotite gneiss (Mo–W) or muscovite schist (Sn–W).     

Maps, newspapers and nationalism: The Finnish historical experience

Cartography has usually been perceived as an objective and exact science. Maps have been seen as actual presentations of the world or the area they depict. But another angle is also possible: they may be interpreted as social or political statements and tools for policy making. Therefore, it is important to aim at interpreting maps as products of their own time, in their own social and historical context. Iconology and hermeneutic interpretation may prove to be useful tools, especially when historical press maps are concerned. I will explore the ways in which maps were used in the Finnish newspapers, magazines and humorous magazines, with examples from the early 1900's to 1941. In many cases, the map was an essential part of the article or caricature, along with the text and other figures. They were often aimed to affect people's opinions and images, and to support Finland's territorial hopes in the Eastern Karelia. Among the other national symbols, such as the flag, national anthem or coat of arms, the map of Finland can be considered as a symbol of nationhood.     

Characterization of organics in whiteshell research area groundwater and the implications for radionuclide transport

Naturally occurring organics in groundwaters of the Whiteshell Research Area (WRA) of southern Manitoba were investigated to assess their potential role in radionuclide transport within granite fractures of the Canadian Shield. A survey of dissolved organic carbon concentrations, carried out to determine the variability in the organic content of these groundwaters, showed average concentrations of 0.8 ± 0.1 mg/L for Fracture Zone 2, 0.8 ± 0.4 mg/L for near-vertical fractures and 2.3 ± 0.8 mg/L for deeper saline groundwater. The dissolved organic carbon consisted mainly of hydrophilic neutral compounds (60 to 75%), and hydrophobic and hydrophilic acids (23 to 39%), along with very small amounts of hydrophobic bases and neutrals, and hydrophilic bases. Significant contamination from drilling operations and plastics, mostly in the form of hydrophobic neutrals, was observed in some samples. These compounds would not contribute to radionuclide migration in a natural system and are not included in the assessment of the organic complexing capacity of these groundwaters.Based on groundwater concentrations of hydrophobic and hydrophilic acids and on the measured car☐ylic functional group content of these acids, the average complexing capacity of natural organics in Whiteshell Research Area groundwaters was calculated to be 2.9 × 10⁻⁶ eq/L. The ability of these organics to complex radionuclides was tested using conditional stability constants from the literature for humic complex formation with Am(III), Th(IV), and U(VI). The chemistry of U(VI) was predicted to be dominated by inorganic complexes and not significantly affected by organics. The literature contains a wide range in values of stability constants for Am(III) and Th(IV) complexes with humics. The aqueous chemistry of Am(III) and Th(VI) could be affected by complexation with natural organics if the higher stability constant values are valid for WRA groundwaters.     

Uncertainty, subjectivity, experience: a comparative pilot study

Mean tendencies and variances of ad hoc mean estimates (field estimates) of some engineering geological parameters were compared to statistically obtained reference values. The latter correspond to the “best” estimates in the sense of approximating so-called reality (Einstein and Baecher, 1982. Probabilistic and statistical methods in engineering geology. Problem statement and introduction to solution. Rock Mech., Suppl. 12: 47–61; Einstein and Baecher, 1983. Probabilistic and statistical methods in engineering geology. Specific methods and examples, Part I: Exploration. Rock Mech. Rock Eng., 16: 39–72). The study was carried out by means of a demoscopic field study on 43 engineering geologists. “Professional experience” was examined by comparing the estimation results of two trial groups, one consisting of people with several years of professional experience, the other one consisting of university students. The biases of the ad hoc estimates due to subjectivity and the limitation of working time at the selected reference outcrops follow statistically describable trends and thus can be analyzed by univariate and multivariate methods. Some geological and psychological hypotheses concerning the mean estimation trends, correlations and discriminations are postulated. Implications on commonly used field estimation methods are discussed.     

Partnership approach to disaster management in Bangladesh: a critical policy assessment

The geographic location of Bangladesh at the confluence of the three mighty river systems of the world renders her one of the most vulnerable places to natural disasters. Human-induced climate change exacerbates the problem. This study shows that the Government of Bangladesh has already established a multi-layered institutional mechanism for disaster management, with formal recognition of the role of various stakeholders. Historically, NGOs and other informal support mechanisms in the country also have made significant contributions during and after disaster recovery. Despite the presence of some strengths, such as long experience in disaster response and recovery, the people’s resilience, and donor support, the current management strategies suffer from a host of policy and institutional weaknesses. Most prominent is the absence of a functioning partnership among the stakeholders within these formal set-ups. What is lacking is the development and embodiment of a culture of collective decision-making in planning, in resource sharing, and in implementing disaster management policies and programs in an integrated and transparent way. The paper suggests a partnership framework to implement prevention, preparedness, response, and recovery phases of disaster management.     

Groundwater contamination with arsenic in Sherajdikhan,Bangladesh: geochemical and hydrological implications

An integrated study has been carried out to elucidate the distribution and occurrence of arsenic in selected groundwater samples in the area of Sherajdikhan, Bangladesh. Arsenic and other parameters (T, pH, EC, Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃ ⁻, SO₄ ²⁻, HCO₃ ⁻, PO₄ ³⁻, Fe, Mn and DOC) have been measured in groundwater samples collected from shallow/deep tube wells at different depths. Hydrogeochemical data suggest that the groundwaters are generally Ca–Mg–HCO₃ and Mg–Ca–HCO₃ types with bicarbonate (HCO₃ ⁻) as the dominant anion, though the other type of water has also been observed. Dissolved arsenic in groundwater ranged from 0.006 to 0.461 mg/l, with 69% groundwater samples exceeded the Bangladesh limit for safe drinking water (0.05 mg/l). Correlation and principal component analysis have been performed to find out possible relationships among the examined parameters in groundwater. Low concentrations of NO₃ ⁻ and SO₄ ²⁻, and high concentrations of DOC, HCO₃ ⁻ and PO₄ ³⁻ indicate the reducing condition of subsurface aquifer where sediments are deposited with abundant organic matter. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter along with reductive dissolution of Fe–Mn oxyhydroxides has being considered the dominant process to release As in the aquifers studied herein.     

Late Cretaceous granitoids in Karakorum,northwest Tibet: petrogenesis and tectonic implications

New zircon LA-ICP-MS U–Pb age, zircon Hf isotope, and whole-rock major and trace elemental data of the Late Cretaceous Ageledaban complex in the Karakorum Terrane (KKT), northwest Tibet, provide new constraints on the tectonic processes of the collision and thickening of the terrane between the Lhasa and Qiangtang terranes. The granitoids from the Ageledaban complex have a variable SiO₂ content, from 62.83 to 73.35 wt.% and A/CNK<1.1 (except for YM61-2). They have rare earth element and trace element patterns that are enriched in light rare earth elements, Rb, Pb, Th, and U, and are depleted in Ba, P, Sr, Ti, and Nb, indicative of weakly peraluminous-metaluminous I-type affinity. Zircon U–Pb dating reveals that the Ageledaban complex was emplaced at ca. 80 Ma. Zircons from the monzogranite and monzonite samples with concordant ²⁰⁶Pb/²³⁸U ages about 80 Ma have a zircon ε_Hf(t) of ?6.6 to ?1.1, corresponding to the Mesoproterozoic Hf crustal model ages (T_DM^C = 1.2–1.6 Ga); the remaining inherited zircons from the monzonite with concordant ²⁰⁶Pb/²³⁸U ages of about 108.1 Ma have ε_Hf(t) values that range from ?8.3 to ?5.0, corresponding to the Mesoproterozoic Hf crustal model ages with an average of 1.6 Ga. These signatures indicate that the Ageledaban granitoids may have been derived from the partial melting of a mixed mantle-crust source. Together with the age and geochemical data in the literature, we propose that the collisional event in the KKT in northwestern Tibet would postdate the northern Lhasa–southern Qiangtang collision, which occurred first in the Amdo in the east and later in the Shiquanhe in central Tibet. Our results support the previous view that the collision of the Bangong–Nujiang suture zone (BNSZ) may be diachronous.