“韩国料”软玉的宝石学研究

＂韩国料＂是目前软玉市场上出现的一个＂新品种＂玉石产品。对一批典型的＂韩国料＂样品进行了常规宝石学测试、偏光显微镜薄片观察、红外光谱以及X射线粉末衍射等测试与分析。结果表明,该＂韩国料＂样品的主要矿物组成为透闪石,其常规宝石学特征以及红外光谱均与软玉的吻合;依据现行的国家标准,其鉴定名称可命名为＂软玉＂或＂和田玉＂。同时,有部分测试结果可作为该＂韩国料＂样品的产地鉴别的参考资料。     

韩国软玉的宝石学特征及结构分析

通过宝石学常规测试、显微硬度计、偏光显微镜观察、扫描电镜测试等方法,对韩国软玉的宝石学参数、结构特征进行了研究。研究表明,韩国产软玉相对密度为2.88～2.95,摩氏硬度为5.45～6.17。偏光显微镜下观察,韩国软玉的主要结构为显微-隐晶质变晶结构,常见交代假像结构、交代残蚀结构、碎裂结构,表明其重结晶作用不强烈。扫描电镜分析表明,韩国软玉的矿物颗粒大小不均,以纤维状为主,同时粗纤维状、柱状斑晶含量较高,纤维状透闪石定向性排列较明显。     

Zircon U‐Pb Dating on Granitoids from the Northern South China Sea and its Geotectonic Relevance

Zircon U-Pb ages of 163.8–100.4 Ma and 146.6–134.5?Ma are obtained for the granitoids from the Pearl River mouth basin, and from southern Guangdong Province, respectively. These new dating data accord well with the crystallization ages of Yanshanian granitoids broadly in the Nanling. The active continental margin of South China, as revealed by a combination of zircon U-Pb data, underwent a key granitoid-dominated magmatism in 165–100?Ma. Its evolution varied temporally, and spatially, registering under control of the paleo-Pacific slab subduction. The granitoids that occurred in 165–150?Ma broadly from the South China Sea to the Nanling are preferably related to two settings from volcanic-arc to back-arc extension, respectively. The activities of Cretaceous granitoids migrated from the southeastern Guangdong (148–130?Ma) to the Pearl River Mouth basin (127–112?Ma), corresponding to the model of a retreating subduction. The subduction-related granitoid magmatism in South China continued until 108–97?Ma. A tectonic transformation from slab-subduction to extension should occur at ~100?Ma.     

Petrological and Geochemical Constraints on the Origin of Strongly Peraluminous Granitoids from the Triassic Guangtoushan Pluton in South Qinling

As an important part of the early Mesozoic granites in the South Qinling tectonic belt (SQTB), the Guangtoushan pluton provides a material basis for research on the composition of magma sources and the effects of peritectic assemblage entrainment (PAE) on the changes in the granite composition. As shown by the results of LA-ICP-MS zircon U-Pb dating, the Guangtoushan pluton was emplaced during the Late Triassic (214–212 Ma) and was formed in the post-collision stage between the SQTB and the Yangtze plate. The collected samples had high SiO2 content and low Cr and Ni contents, indicating that the magmas did not undergo significant crust-mantle mixing during their evolution. The Guangtoushan granitoids were distributed along the trend line of magmatic fractional crystallization in the F–An–Or diagram. This result, combined with the relatively homogeneous Sr-Nd isotopic composition, implies that the Guangtoushan pluton underwent slight assimilation and contamination. As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid-absent experimental melts, the magma sources of the Guangtoushan granitoids contain a variety of materials, such as graywackes, pyroclastic graywackes, and pelites and are not derived from lower crustal mafic rocks. The correlation between the maficity and the major and trace elements further indicates that the strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite-bearing crustal rocks and its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals.     

南秦岭张家坝岩体和新院岩体地球化学特征及其形成环境

南秦岭中生代张家坝岩体和新院岩体的LILE相对富集、HFSE贫化,高钾、富Sr（（498—623）×10^-6）、低Y（（5．57～24）×10^-6）和Yb（（0．52～2．13）×10^-6）,Eu异常微弱,显示了地壳增厚背景下下部地壳物质部分熔融所形成的高钾钙碱性花岗岩特征。岩体内的包体中出现长宽比很高的针状磷灰石,且边缘发育冷凝边结构,包体与寄主岩间存在明显的成分间断,并构成了两个不同的岩浆演化趋势和它们所具有的不同稀土特征,证明它们为来自两个不同源区岩浆混合的产物,同时指示秦岭地区中生代时期发生了一次壳幔混合作用和重要的地壳垂向增生事件。     

南祁连党河南山花岗岩类特征及其构造环境

党河南山地区地处南祁连重要成矿带,区内花岗岩类岩体包括扎子沟岩体、鸡叫沟岩体及贾公台岩体,伴有不同程度的金、铜矿化。扎子沟岩体主要由花岗闪长岩组成,侵位于震旦纪火山岩系。鸡叫沟岩体主要由石英二长闪长岩组成,贾公台岩体主要由斜长花岗岩组成,两者侵位于奥陶纪碎屑岩系。3个岩体Rb-Sr等时线年龄分别为(510.85±14)Ma、(395.06±51)Ma及(355±91)Ma,前者对应于早-中寒武世,后二者对应于志留纪-泥盆纪。3个岩体均属于钙碱性花岗岩系列,其中扎子沟岩体属于该系列的中钾花岗闪长岩系列,鸡叫沟岩体属于高钾二长岩系列,贾公台岩体属于低钾奥长花岗岩系列。综合岩相学、岩石化学及微量元素和稀土元素的地球化学特征,区内3个岩体均形成于I型活动陆缘环境,为中南祁连造山带加里东期构造岩浆活动的产物。     

When seed fails: The contested nature of neoliberalism in South Korea

In recent years, many geographers have examined the ways that the production of nature has changed as a result of neoliberal practices. In this paper we examine a conflict in South Korea that started when some Chinese-cabbage seeds were affected by a virus, causing crop failure. This failure came shortly after liberalization in the Korean seed industry led to foreign ownership of the firm that sold the seed. We focus in particular on the farmers’ creative political responses - and their subsequent defeat in court. Drawing on Antonio Gramsci’s insights on politics, science, and law, we examine how the seed failure came to be evaluated through scientific and legal practices. We argue that the adjudication of the truth of the seed failure through science and law reveals how socionatures are contested under prevailing hegemonic conditions. These conditions are both general and specific: although law and science are relatively hegemonic spheres of truth-production in all capitalist societies, the ways that the seeds were disputed and evaluated were distinctly Korean.     

Enrichment of Mantle-derived Fluids in the Formation Process of Granitoids: Evidence from the Himalayan Granitoids around Kunjirap in the Western Qinghai-Tibet Plateau

Taking the Himalayan granitoids around Kunjirap in the western Qinghai-Tibet plateau as an example, the authors present in this paper the characteristics of the granitoids rich in mantle-derived fluid components and discuss their rock-forming mechanism. The research results indicate that the rock assemblage of the studied granitoids involves diopside syenite-diopside granite-biotite (monzonitic) granite, consisting mainly of K-feldspar, oligoclase, quartz, iron-phlogolite, diopside and edenite. The rocks are rich in mantle-derived fluid components of volatiles including F, alkali metal elements such as K, Na, Rb, Sr and Ba, and radiogenic heat-producing elements such as U and Th. They were generated by the influx of mantle-derived fluids into the lower crust to give rise to partial melting during the lithosphere thinning in the Qinghai-Tibet plateau.     

Migrant times beyond the life course: The temporalities of foreign English teachers in South Korea

The study of life course has become a central feature of geographical and other social science approaches to youth and migration. It has offered scholars possibilities to explore the timing of events, experiences of time and in the context of migration, the opportunity to analyse mobility patterns in relation to life stages and transitions. Yet, despite this emphasis, much life-course research rests on a limited understanding of time characterised as a linear or even static entity that regulates life in a way that occludes the complex directionality and rhythms of time. In this paper we seek to push beyond these limitations of life course research by developing broader theoretical understandings of time in migration. In particular, we develop a Heideggerian analysis of the migration stories of western English teachers in South Korea, an example of migration as part of a youth–adult transition. Our analysis reveals that the mobilities of English teachers need to be understood in much more complex and relational ways and we draw attention to their more-than-subjective temporalities, questions of attunement to being (affect) and temporal openness in migration. Through this discussion the paper highlights three key areas for further development of scholarly understandings of time in migration: the situatedness of migrants, the holistic character of migration as a happening in the world, and the eventfulness of migration, always characterised by an openness of possibility for emergent spatio-temporal differentiation.     

Property-based redevelopment and gentrification: The case of Seoul, South Korea

The urban experiences of South Korea in times of its rapid urbanisation and economic growth show that wholesale redevelopment had been a dominant approach to urban renewal, leading to redevelopment-induced gentrification. This was led by a programme known as the Joint Redevelopment Programme, transforming urban space that was once dominated by informal settlements into high-rise commercial housing estates. This paper tries to explain how this approach was possible at city-wide scale in its capital city, Seoul. Through the examination of redevelopment processes in a case study neighbourhood, it puts forward three arguments. First, the development potential arising from the rent gap expansion through under-utilisation of dilapidated neighbourhoods provided material conditions for the sustained implementation of property-based redevelopment projects. Second, this paper critically examines the dynamics of socio-political relations among various property-based interests embedded in redevelopment neighbourhoods, and argues that external property-based interests have enabled the full exploitation of development opportunities at the expense of poor owner-occupiers and tenants. Third, South Korea had been noted for its strong developmental state with minimum attention to redistributive social policies. The Joint Redevelopment Programme in Seoul was effectively a market-oriented, profit-led renewal approach, in line with a national housing strategy that favoured increased housing production and home-ownership at the expense of local poor residents’ housing needs.     

Spinel granulite in Odesan area, South Korea: Tectonic implications for the collision between the North and South China blocks

Spinel granulite formed in the Fe–Al-rich layers in migmatitic gneiss adjacent to a late Paleozoic collision-related mangerite intrusion in the Odesan area, eastern Gyeonggi Massif, South Korea, contains the high-temperature (HT) assemblage Crd + Spl + Crn. Spinel and cordierite compositions indicate peak metamorphic conditions of 914–1157 °C. Retrograde metamorphism reached amphibolite facies where garnet and cordierite broke down to biotite, sillimanite and quartz. These conditions, and the reactions inferred from mineral textures, are consistent with a clockwise P–T path. Metamorphic zircon overgrowths in the spinel granulite and enclosing migmatitic gneiss, dated by SHRIMP U–Pb, yield Permo-Triassic ages of 245 ± 10 and 248 ± 18 Ma respectively, consistent with the metamorphism being a product of the late Paleozoic collision between the North and South China blocks within South Korea. The zircon core ages and textures suggest that the ultimate source of the spinel granulite was a Paleoproterozoic (1852 ± 14 Ma) igneous rock. The protolith of the host migmatitic gneiss was a sediment derived principally from 2.49, 2.16 and 1.86 Ga sources. The age and conditions of spinel granulite metamorphism are similar to those of spinel-bearing granulite in the Higo terrane in west-central Kyushu (250 Ma, > 950 °C at 8–9 kbar), consistent with a continuation of the Dabie-Sulu collision zone into Japan through the Odesan area.     

Petrogenesis of Adakitic Porphyries in an Extensional Tectonic Setting, Dexing, South China: Implications for the Genesis of Porphyry Copper Mineralization

The Dexing adakitic porphyries (quartz diorite–granodioriteporphyries), associated with giant porphyry Cu deposits, arelocated in the interior of a continent (South China). They exhibitrelatively high MgO, Cr, Ni and Sr contents, high La/Yb andSr/Y ratios, but low Yb and Y contents, similar to adakitesproduced by slab melting associated with subduction. However,they are characterized by bulk Earth-like Nd–Sr isotopecompositions (_Nd(t) = –1·14 to +1·80 and(⁸⁷Sr/⁸⁶Sr)_i = 0·7044 – 0·7047), and highTh (12·6–27·2 ppm) contents and Th/Ce (0·19–0·94)ratios, which are different from those of Cenozoic slab-derivedadakites. Sensitive High-Resolution Ion Microprobe (SHRIMP)geochronology studies of zircons reveal that the Dexing adakiticporphyries have a crystallization age of 171 ± 3 Ma.This age is contemporaneous with Middle Jurassic extension withinthe Shi-Han rift zone, and within-plate magmatism elsewherein South China, indicating that the Dexing adakitic porphyrieswere probably formed in an extensional tectonic regime in theinterior of the continent rather than in an arc setting. Theirhigh Th contents and Th/Ce ratios, and Middle Jurassic age,argue against an origin from a Neoproterozoic (1000 Ma) stalledslab in the mantle. Taking into account available data for theregional metamorphic–magmatic rocks, and the present-daycrustal thickness (31 km) in the area, we suggest that the Dexingadakitic porphyries were most probably generated by partialmelting of delaminated lower crust, which was possibly triggeredby upwelling of the asthenospheric mantle due to the activityof the Shi-Hang rift zone. Moreover, the Dexing adakitic magmasmust have interacted with the surrounding mantle peridotiteduring their ascent, which elevated not only their MgO, Cr andNi contents, but also the oxygen fugacity (fO₂) of the mantle.The high fO₂ could have induced oxidation of metallic sulfidesin the mantle and mobilization of chalcophile elements, whichare required to produce associated Cu mineralization. Therefore,the Cu metallogenesis associated with the Dexing adakitic porphyriesis probably related to partial melting of delaminated lowercrust, similar to the metallogenesis accompanying slab melting. KEY WORDS: adakite; lower crust; delamination; porphyry copper deposit, South China     

赣南加里东期阳埠(垇子下)岩体的锆石年龄、构造背景及含矿性评价

阳埠岩体是赣南著名的含稀土岩体之一,但研究程度低,缺乏精确的同位素年代学资料。文章对阳埠岩体风化壳的锆石样品进行了激光剥蚀-多接收器电感耦合等离子体质谱(LA-MC-ICPMS)U-Pb定年,获得206Pb/238U加权平均年龄为(461.1±1.3)Ma,说明该岩体形成于中奥陶世。区域上阳埠岩体与武功山山庄岩体(461 Ma)、赣南上犹岩体(464 Ma)、云开大山花岗岩(465～467 Ma)等为同时代岩体,属华南加里东晚期第一次岩浆活动峰期产物,暗示华南加里东期褶皱造山运动的开始。结合江西省加里东期花岗岩的地球化学资料,发现多数岩体的稀土总量较高,具备成矿母岩的首要条件。今后应对南岭地区加里东期花岗岩含矿性评价及找矿工作给予重视。     

Temporal, Spatial and Geochemical Discriminations of Granitoids in South Korea

Abstract: Five groups of the Phanerozoic granitoids in South Korea can be deduced from their temporal and spatial distributions: (1) Jurassic granitoids in the Gyeonggi massif, (2) Permo-Jurassic granitoids in the Ogcheon belt, (3) Permo-Jurassic granitoids in the Yeongnam massif, (4) Cretaceous granitoids in the Ogcheon belt, and (5) Cretaceous granitoids in the Gyeongsang basin. Though the granitoids of each group generally show calc-alkaline and orogenic natures, the petrological, geochemical and genetical features are different with each other. The Permo-Jurassic granitoids in the Ogcheon belt have lower contents of Al₂O₃, Fe₂O₃, CaO, P₂O₅, but higher of FeO, FeOT, MgO, K₂O than those in the Yeongnam massif. From higher feature of K₂O, Na₂O+K₂O and K₂O/Na₂O, the Ogcheon belt seems to have been located at closer continent side relative to the Yeongnam massif during Permo-Jurassic time. From lower values of Fe₂O₃/FeO and magnetic susceptibility the granitoids of the Ogcheon belt had been solidified under more reducing environment than those of the Yeongnam massif. The Cretaceous granitoids in the Ogcheon belt have lower contents of TiO₂, Fe₂O₃, FeO, FeOT, CaO and P₂O₅, but higher of MgO, K₂O, Na₂O+K₂O and K₂O/Na₂O than those in the Gyeongsang basin. This feature indicates that the Ogcheon belt would correspond to the continental environment of magma genesis during Cretaceous time. Higher values of Fe₂O₃/FeO and magnetic susceptibility in the Cretaceous granitoids in the Gyeongsang basin suggest that the granitoids had been solidified under highly oxidizing environment. From the particular chemical features of K₂O, Na₂O+K₂O and K₂O/Na₂O, the Permo-Jurassic granitoids in the Ogcheon belt, the Yeongnam massif as well as the Cretaceous ones in the Gyeongsang basin can be categorized to the continental margin type granite. The Jurassic granitoids in the Gyeonggi massif are possibly of collision type, and the Cretaceous granitoids in the Ogcheon belt of post–orogenic, intra–conti–nent type. The Jurassic granitoids in the Gyeonggi massif had been possibly generated by crustal melting during the collision of Gyeonggi massif to the northern Pyeongnam basin block. The Cretaceous granitoids in the Ogcheon belt had been emplaced at the hinterland of the continental margin during post-orogenic stage of the Honam Shear Zone. The Cretaceous granitoids in the Gyeongsang basin are often compared with Japanese Cretaceous?Paleogene granitoids in their geochemical and genetical natures. For the granitoid composition, the granitoids in the Gyeongsang basin are higher in Fe₂O₃, Fe₂O₃/FeO, Na₂O, K₂O, Na₂O+K₂O and K₂O/Na₂O, but lower in Al₂O₃, FeO, MnO, CaO and P₂O₅ than the Japanese granitoids. The contents of TiO₂, FeOT and MgO are similar in both granitoids. This geochemical contrast would imply that the Cretaceous granitoid magmas in the Gyeongsang basin had been originated at closer place to the continent side under more tensional field, and solidified under more oxidizing environment than the coeval Japanese granitoid magmas.     

Isotope Geochemistry of Granitoids in South China and Their Metallogeny

Abstract: On the basis of data of initial strontium ratios for over 300 plutons, neodymium isotopes for 240 plutons and oxygen isotopes for more than 200 plutons, the granites of South China are divided into six belts which are different from each other in petrology, geochemistry and mineralization. The similar Nd isotopic composition between the peraluminous granites and Proterozoic crust reveals that there is intermediate to felsic composition crust at mid-crustal depth throughout the South China interior. The six granitic belts mentioned above belong to different lithospheric plates with different composition basement. Differences in the extent and nature of interaction between mantle and crusts in different geodynamic setting and the different extent of differentiation of magma have all controlled the characteristics of the granites and their related mineralization.     

Isotope geochemistry of Jeongok basalts,northernmost South Korea: Implications for the enriched mantle end-member component

South Korea separates two mantle source domains for Late Cenozoic intraplate volcanism in East Asia: depleted mid-ocean-ridge basalt (MORB) mantle-enriched mantle type 1 (DMM-EM1) in the north and DMM-EM2 in the south. We determined geochemical compositions, including Sr, Nd, Pb, and Hf isotopes for the Jeongok trachybasalts (∼0.51 to 0.15 Ma K–Ar ages) from northernmost South Korea, to better constrain the origin and distribution of the enriched mantle components. The Jeongok basalts exhibit light rare earth element (LREE)-enriched patterns ([La/Yb]_N = 9.2–11.6). The (La/Yb)_N ratios are lower than that of typical oceanic island basalt (OIB). On a primitive mantle-normalized incompatible element plot, the Jeongok samples show OIB-like enrichment in highly incompatible elements. However, they are depleted in moderately incompatible elements (e.g., La, Nd, Zr, Hf, etc.) compared with the OIB and exhibit positive anomalies in K and Pb. These anomalies are also prime characteristics of the Wudalianchi basalts, extreme EM1 end-member volcanics in northeast China. We have compared the geochemistry of the Jeongok basalts with those of available Late Cenozoic intraplate volcanic rocks from East Asia (from north to south, Wudalianchi, Mt. Baekdu and Baengnyeong for DMM-EM1, and Jeju for DMM-EM2). The mantle source for the Jeongok volcanics contains an EM1 component. The contribution of the EM1 component to East Asian volcanism increases toward the north, from Baengnyeong through Jeongok to Mt. Baekdu and finally to Wudalianchi. Modeling of trace element data suggests that the Jeongok basalts may have been generated by mixing of a Wudalianchi-like melt (EM1 end-member) and a melt that originated from a depleted mantle source, with some addition of the lithospheric mantle beneath the Jeongok area. In Nd–Hf isotope space, the most enriched EM1-component-bearing Jeongok sample shows elevation of ¹⁷⁶Hf/¹⁷⁷Hf at a given ¹⁴³Nd/¹⁴⁴Nd compared with OIB. Recycled pelagic sediments may explain the EM1-end-member component of northeastern Asian volcanism, possibly from the mantle transition zone.     

Petrogenesis of Indosinian Granitoids in Middle-Segment of South Qinling Tectonic Belt: Constraints from Sr-Nd Isotopic Systematics

South Qinling Tectonic Belt (SQTB) is located between the Shangzhou-Danfeng and Mianxian-Lueyang sutures. There are a lot of early Mesozoic granitoid plutons in its middle segment, comprising the Dongjiangkou-Zhashui granitoid plutons at the northeast, Huayang-Wulong-Laocheng granitoid plutons at the central part, Xiba granitoid pluton at the northwest and Guangtoushan-Liuba granitoid plutons at the southwest. These Indonisian granitoids contain a mass of various scale mafic enclaves, which show sometimes clear boundaries and sometimes transitional boundaries with their host granitoids. These granitoids also exhibit metaluminous to peraluminous series, commonly higher Mg# and a wide range of petrochemistry from low-K tholeiite series, through mid-K and high-K calc-alkaline series to shoshonite series and predominated samples are attributed to mid-K and high-K calc-alkaline series. Detailed analyses in Sr-Nd isotopic systematics and petrochemistry reveal that there may be regionally initial granitoid magma of the Indonisian granitoid plutons, comprising Dongjiangkou-Zhashui, Huayang-Wulong-Laocheng, Xiba, and Guangtoushan-Liuba granitoid plutons, which were produced by hybrids of magmas in various degrees, and the initial magmas were derived from both the mantle and the lower continental crust (LCC) sources in the SQTB. The initial granitoid magma further did the magma hybrid with the magmas from the LCC, crystallization fractionation, and assimilation with upper crustal materials during their emplacement to produce these granitoid plutons in the SQTB. These magmatism processes are most likely to occur under continent marginal arc and syn-collision to post-collision tectonic backgrounds.     

苏鲁造山带五莲新元古代花岗岩类成因的Sr-Nd同位素证据

五莲新元古代花岗岩类分布于五莲断裂以北, 动力变形强, 但变质程度弱, 仅达到绿片岩相.岩性以黑云正长花岗质为主, 少数为石英正长质.岩石中Sr同位素初始值的变化范围很广, 从0.697 306~0.753 765, 除了部分是由于源区的不均一或多源不同比例混合外, 岩浆侵位过程中或固结后的次生扰动可能也起着一定的作用.而它们的ε_Nd (750 Ma) 均为负值且变化范围广(-3.1~-24.3), Nd同位素二阶段模式年龄从1.7~3.4 Ga, 均显示它们的源区以古老的地壳为主, 但具有多源混合的特征.推测五莲新元古代花岗岩类最可能的成因是太古代的TTG片麻岩(主要是其中的英云闪长质组分) 在压力约0.8 Gpa (相当于~25 km的中下地壳) 条件下发生部分熔融, 并混入了不同比例的年轻地幔来源物质.地幔来源物质的加入对于五莲新元古代花岗岩类的成因有重要的影响.      

阿尔金山西南段花岗岩类的时空变化与构造作用——来自钾钠含量变化的证据

探讨阿尔金山花岗岩浆作用与构造作用的相互关系有助于全面认识其构造性质和演化特点。系统收集阿尔金山西南段花岗岩类岩石化学数据,统一采用Collins et al.(1982)提出的K2O-Na2O分类图解法,获得各个地史时期花岗岩类的成因类型。五台期均为I型,岩体规模较大,呈近东西向集中成片分布。吕梁期为A型,岩体规模较小,呈北西西向条带状分布于五台期岩体的东北边缘。四堡-晋宁期以S型为主,岩体规模大、分布广、呈北东东向展布。加里东期总体以A型为主,边界断裂带附近I型增多,岩体规模最大、范围最广,总体呈北东东向(北东向)展布。海西期以I型为主,规模小,断续分布于南缘断裂和西北缘断裂的西南端。燕山-喜马拉雅期以A型为主,规模最小,分布零星。五台期至晋宁期岩体主要分布于阿尔金山三条边界断裂所围限的隆起区内,并且在同一时期岩石成因类型具有相对一致性;加里东期隆起区内主体岩石类型与边界断裂带附近及其外侧存在明显差异;海西至喜马拉雅期仅分布于边界断裂带内或东南邻区。上述情况说明,自五台期至喜马拉雅期阿尔金山地区花岗岩类的成因类型、岩体发育规模、展布方向都呈现出有规律的反复交替变化的特点,这是花岗岩浆作用受构造发展演化的不同阶段和不同方向构造作用的交替变化控制的结果。     

Determining the condition of groundwater in evaluating the need for corrective measures: a case for the national groundwater-monitoring network in South Korea

Groundwater data (water level, electrical conductivity (EC) and temperature) have been collected since 1995 from the national groundwater-monitoring stations in South Korea. Recently, substantial groundwater-level decline and deterioration of groundwater quality were reported at several stations. Relevant authorities undertook to investigate the groundwater hazards and to devise mitigation measures for selected monitoring stations. However, there were no criteria to determine the status of the groundwater level and EC, compared with historic data. A methodology is presented, which defines the groundwater condition. Using the suggested criteria, water level and EC data are classified into normal, watch and warning levels, leading to different administrative measures and technical investigations. The primary criterion compares the observed values for the evaluation year (e.g. 2003) and the historic values of normal years preceding the evaluation year (e.g. 1996–2002), using box plots. The secondary criterion uses variation trends of the values with the aid of parametric and non-parametric trend tests. Final decisions are dependent on scores assigned to each test. According to the criteria suggested, detailed investigations and mitigation measures for water level decline are required for seven stations and those for water quality are needed for 18 stations because they reside within the warning classification.