朝鲜平南盆地古元古界-下古生界沉积岩碎屑锆石年龄谱对比及意义   总被引：3，自引：3，他引：0  

杨正赫  彭澎  郑哲寿  朴雄  文正根  金哲贤  苟贤哲 《岩石学报》2016,32(10):3155-3179

中朝古陆(华北古陆)平南盆地面积~25000km~2,位于朝鲜半岛中部,发育从中元古界到下古生界地层,但经历了低级变质作用(绿片岩相及以下)。变质基底岩石中有一套角闪岩相-麻粒岩相的变质的古元古界地层。本文根据盆地不同时代沉积岩碎屑锆石/变质锆石U-Pb LA-ICP MS年龄数据讨论沉积源区的变化,并对区域演化进行制约。甑山群/杂岩为盆地基底岩系,变质砂岩样品中碎屑锆石出现ca.2500~2100Ma的年龄峰值。另外,36.5亿年的碎屑锆石是朝鲜迄今发现的最古老碎屑锆石;夕线榴片麻岩样品记录了~1850Ma(1859±9Ma)的变质年龄;推测甑山群沉积于ca.2100~1900Ma,变质于1850 Ma。黄海群局限分布于朝鲜半岛中部,碎屑锆石年龄谱显示~1850 Ma的峰值,可见~1250 Ma的年龄,推测对应物源为古元古代基底岩浆岩和变质岩系;结合其上覆直岘群的沉积时代,推测地层沉积于ca.1250~1000Ma。直岘群是平南盆地分布最广的地层之一,底部长峰组样品显示明显的~1850Ma的峰值,而其上第二个和第三个组则显示明显的ca.1400~1600Ma和ca.1000~1200 Ma年龄峰值,~1850 Ma年龄很少;推测直岘群开始沉积时,物源主体是盆地基底岩系,但之后出现大量中元古代物质;推测其沉积时代为ca.1000~900Ma。黄州群有~1850Ma和~2500Ma的峰值,另外,还有较少的ca.1000~1200Ma及1400~1600 Ma年龄,表明沉积物源主体仍是基底岩系,可能有中新元古代沉积岩(黄州群-直岘群)的再沉积。这些沉积岩碎屑锆石年龄峰值与辽东和山东半岛沉积地层相似,并且中新元古代地层中均有大量1000~1200Ma及1400~1600Ma的物质,推测可能来自华北古陆之外,如圣弗朗西斯科克拉通。  相似文献   

白头山火山渣锥的岩浆演化研究     

朴成哲  金东旭  赵日元  金守哲  金仁哲 《岩石学报》2016,32(10):3214-3224

火山渣锥是白头山(或长白山)火山喷发的重要产物,主要沿熔岩台地周边呈圆锥状寄生小火山锥体分布。野外特征显示,火山渣是火山渣锥的重要组成;岩石手标本显示,火山渣具有气孔构造,样品自顶部至底部,颜色从赤色、赤褐色,向褐色、灰色发生转变。地球化学特征表明,火山渣岩性包括玄武岩、粗面玄武岩、玄武岩质粗面安山岩、粗面安山岩岩,具有较高SiO_2(46.22%~55.38%),Al_2O3含量(15.28%~22.11%),低MgO(2.05%~4.94%),FeOT(6.79%~14.76%)的特征;同时具有较高的碱Na_2O/K_2O(Na_2O/K_2O1)比值,为钠质火山岩。其轻稀土(LREE)和重稀土(HREE)分异明显,具有弱的δEu正异常,并且具有富集K、Rb、Ba、Sr等大离子亲石元素(LILE)和相对亏损Nb、Ti等高场强元素(HFSE)的特征。此外,火山渣的分异指数(DI)范围为36.93~64.48,高于造盾阶段的幔源玄武岩的分异指数;其固结指数(SI)为10.73~24.09,低于早期幔源玄武岩的固结指数(SI=25~45),这些特征说明火山渣成分发生了较高程度的岩浆分异作用。同时,火山渣的Nb/La、Sm/Nd、La/Nb和Ba/Nb比值几乎全部介于幔源玄武岩和大陆地壳之间,说明具有明显的地壳混染的特征。因此,我们认为研究区火山渣的岩浆可能是由幔源基性玄武岩上升过程中发生分离结晶和地壳混染作用形成的。  相似文献   

Geochemistry and Petrogenesis of Neoarchean Metamorphic Mafic Rocks in the Wutai Complex   总被引：1，自引：0，他引：1  

K. H. PARK 《《地质学报》英文版》2006,80(6):899-911

Neoarchean metamorphic mafic rocks in the lower and the middle Wutai Complex mainly comprise metamorphic gabbros, amphibolites and chlorite schists. They can be subdivided into three groups according to chondrite normalized REE patterns. Rocks in Group #1 are characterized by nearly flat REE patterns （Lan/Ybn=0.86-1.3）, the lowest total REEs （29-52 ppm）, and weak negative to positive Eu anomalies （Eun/Eun=0.84-1.02）, nearly flat primitive mantle normalized patterns and strong negative Zr（Hf） anomalies. Their geochemical characteristics in REEs and trace elements are similar to those of ocean plateau tholeiite, which imply that this group of rocks can represent remnants of Archean oceanic crust derived from a mantle plume. Rocks in Group #2 are characterized by moderate total REEs （34-116 ppm）, LREE-enriched （Lan/Ybn=1.76-4.34） chondrite normalized REE patterns with weak Eu anomalies （Eun/Eun=0.76-1.16）, and negative Nb, Ta, Zr（Hf）, Ti anomalies in the primitive mantle normalized spider diagram. The REE and trace element characteristics indicate that they represent arc magmas originating from a sub-arc mantle wedge metasomatized by slab-derived fluids. Rocks in Group #3 are characterized by the highest total REEs （61-192 ppm）, the strongest LREEs enrichment （Lan/Ybn=7.12-16） with slightly negative Eu anomalies （Eun/Eun=0.81-0.95） in the chondrite normalized diagram. In the primitive mantle normalized diagram, these rocks are characterized by large negative anomalies in Nb, Ta, Ti, negative to no Zr anomalies. They represent arc magmas originating from a sub-arc mantle wedge enriched in slab-derived melts. The three groups of rocks imply that the formation of the Neoarchean Wutai Complex is related to mantle plumes and island-arc interaction.  相似文献   

The Effect of the Irrigated Gudeuljang Paddy System on Biodiversity on Cheongsan-do (“island”)     

PARK Eunha  OH Choong-Hyeon 《资源与生态学报(英文版)》2016,7(3):218-222

This study has been conducted to identify the characteristics of the biodiversity promoted and maintained by gudeuljang paddy field. For this purpose, a literature review was used to identify the distribution of gudeuljang paddy field on Cheongsan-do. Based on the results of the review, a target area was selected to conduct an investigation of the flora of the vascular plants and a phytosociological examination, which included general farmlands and neighboring areas, was made for comparison. As a result of the study, we were able to identify the differences between the type of gudeuljang paddy field that uses continuous irrigation and other types of land use. We found that the unique physical structure for water passage found in gudeuljang paddy fields with continuous irrigation is more effective in promoting biodiversity than the other types of land use in this area. In conclusion, the presence of gudeuljang paddy fields on Cheongsan-do contributes more to the creation of an appropriate biohabitat than it detracts from such a creation. Also, the presence of gudeuljang paddy fields is significant in that it exercises positive influence on the promotion of biodiversity, such as propagation of species, and the connection of habitats in adjacent forest, village, and farm lands. Our result shows that the maintenance and preservation of gudeuljang paddy fields on Cheongsan-do plays a crucial part in the preservation and maintenance of the biodiversity for vegetation that grows among rocks and in adjacent forest areas.  相似文献   

Integration of the nuclease protection assay with sandwich hybridization (NPA-SH) for sensitive detection of Heterocapsa triquetra     

PARK Mirye  PARK So Yun  HWANG Jinik  JUNG Seung Won  LEE Juyun  CHANG Man  LEE Taek-Kyun 《海洋学报(英文版)》2018,37(5):107-112

Microalgae are photosynthetic microorganisms that function as primary producers in aquatic ecosystems. Some species of microalgae undergo rapid growth and cause harmful blooms in marine ecosystems. Heterocapsa triquetra is one of the most common bloom-forming species in estuarine and coastal waters worldwide. Although this species does not produce toxins, unlike some other Heterocapsa species, the high density of its blooms can cause significant ecological damage. We developed a H. triquetra species-specific nuclease protection assay sandwich hybridization (NPA-SH) probe that targets the large subunit of ribosomal RNA (LSU rRNA). We tested probe specificity and sensitivity with five other dinoflagellates that also cause red tides. Our assay detected H. triquetra at a concentration of 1.5×10⁴ cells/mL, more sensitive than required for a red-tide guidance warning by the Korea Ministry of Oceans and Fisheries in 2015 (3.0×10⁴ cells/mL). We also used the NPA-SH assay to monitor H. triquetra in the Tongyeong region of the southern sea area of Korea during 2014. This method could detect H. triquetra cells within 3 h. Our assay is useful for monitoring H. triquetra under field conditions.  相似文献   

Preliminary Results of the Ground-Based Orographic Snow Enhancement Experiment for the Easterly Cold Fog （Cloud） at Daegwallyeong during the 2006 Winter     

Myoung-Joo LEE  Ki-Ho CHANG  Gyun-Myoung PARK  Jin-Yim JEONG  Ha-Young YANG  Ki-Deok JEONG  Joo-Wan CHA  Sung-Soo YUM  Jae-Cheol NAM  Kyungsik KIM  Byung-Chul CHOI 《大气科学进展》2009,26(2):222-228

The snow enhancement experiments, carried out by injecting AgI and water vapor into orographically enhanced clouds (fog), have been conducted to confirm Li and Pitter’s forced condensation process in a natural situation. Nine ground-based experiments have been conducted at Daegwallyeong in the Taebaek Mountains for the easterly foggy days from January–February 2006. We then obtained the optimized condi- tions for the Daegwallyeong region as follows: the small seeding rate (1.04 g min-1) of AgI for the easte...  相似文献   

Statistical Downscaling for Multi-Model Ensemble Prediction of Summer Monsoon Rainfall in the Asia-Pacific Region Using Geopotential Height Field   总被引：16，自引：1，他引：15  

ZHU Congwen  Chung-Kyu PARK  Woo-Sung LEE  Won-Tae YUN 《大气科学进展》2008,25(5):867-884

The 21-yr ensemble predictions of model precipitation and circulation in the East Asian and western North Pacific （Asia-Pacific） summer monsoon region （0°-50°N, 100° 150°E） were evaluated in nine different AGCM, used in the Asia-Pacific Economic Cooperation Climate Center （APCC） multi-model ensemble seasonal prediction system. The analysis indicates that the precipitation anomaly patterns of model ensemble predictions are substantially different from the observed counterparts in this region, but the summer monsoon circulations are reasonably predicted. For example, all models can well produce the interannual variability of the western North Pacific monsoon index （WNPMI） defined by 850 hPa winds, but they failed to predict the relationship between WNPMI and precipitation anomalies. The interannual variability of the 500 hPa geopotential height （GPH） can be well predicted by the models in contrast to precipitation anomalies. On the basis of such model performances and the relationship between the interannual variations of 500 hPa GPH and precipitation anomalies, we developed a statistical scheme used to downscale the summer monsoon precipitation anomaly on the basis of EOF and singular value decomposition （SVD）. In this scheme, the three leading EOF modes of 500 hPa GPH anomaly fields predicted by the models are firstly corrected by the linear regression between the principal components in each model and observation, respectively. Then, the corrected model GPH is chosen as the predictor to downscale the precipitation anomaly field, which is assembled by the forecasted expansion coefficients of model 500 hPa GPH and the three leading SVD modes of observed precipitation anomaly corresponding to the prediction of model 500 hPa GPH during a 19-year training period. The cross-validated forecasts suggest that this downscaling scheme may have a potential to improve the forecast skill of the precipitation anomaly in the South China Sea, western North Pacific and the East Asia Pacific regions, wh  相似文献   

Experiment on Dust Flux During Duststorm Periods over Desert Area          下载免费PDF全文

ZHANG Hongsheng  ZHU Hao  PENG Yan  KANG Ling  CHEN Jiayi  Soon-Ung PARK 《Acta Meteorologica Sinica》2008,22(2):239-247

The present study investigates the characteristics of turbulent transfer and the conditions for dust emission and transport using the dust concentration and micrometeorological data obtained during dust events occurring in the spring of 2004 over the Hunshandake desert area. The turbulent exchange coefficients and turbulent fluxes of momentum and heat are calculated. The relationships between dust flux, friction velocity, and wind speed are also explored. The results show that thermal turbulence is dominant during daytime of non-dusty days. The dynamic turbulence increases obviously and the sensible heat flux reduces by different degrees during dust events. There is an efficient downward transfer of momentum before duststorm occurrence, and both the dynamic turbulence and the thermal turbulence are important in the surface layer. The dynamic turbulence even exceeds the thermal turbulence during severe duststorm events. The values of dust flux vary in the range of -5 5, -30 30, and -200-300 μg m^-2 s^-1 during non-dusty days, blowing dust, and duststorm events, respectively. A slight upward transport of dust is observed during non-dusty days. The dust flux gradually varies from positive to negative during duststorm periods, which indicates the time evolution of dust events from dust rising to stably suspending and then deposition. The dust flux is found to be proportional to u＊^3. The threshold values of wind speed and friction velocity are about 6 and 0.4 m s^-1, respectively.  相似文献   

Orbital‐ and millennial‐scale climate and vegetation changes between 32.5 and 6.9k cal a BP from Hanon Maar paleolake on Jeju Island,South Korea          下载免费PDF全文

JUNGJAE PARK  HYOUN SOO LIM  JAESOO LIM  KEUN BAE YU  JINMU CHOI 《第四纪科学杂志》2014,29(6):570-580

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Geochemistry of peridotite xenoliths in alkali basalts from Jeju Island, Korea   总被引：1，自引：0，他引：1  

SEONG HEE  CHOI  JONG IK  LEE  CHUNG-HWA  PARK  JACQUES  MOUTTE 《Island Arc》2002,11(4):221-235

Abstract   Ultramafic xenoliths in alkali basalts from Jeju Island, Korea, are mostly spinel lherzolites with subordinate amounts of spinel harzburgites and pyroxenites. The compositions of major oxides and compatible to moderately incompatible elements of the Jeju peridotite xenoliths suggest that they are residues after various extents of melting. The estimated degrees of partial melting from compositionally homogeneous and unfractionated mantle to form the residual xenoliths reach 30%. However, their complex patterns of chondrite-normalized rare earth element, from light rare earth element (LREE)-depleted through spoon-shaped to LREE-enriched, reflect an additional process. Metasomatism by a small amount of melt/fluid enriched in LREE followed the former melt removal, which resulted in the enrichment of the incompatible trace elements. Sr and Nd isotopic ratios of the Jeju xenoliths display a wide scatter from depleted mid-oceanic ridge basalt (MORB)-like to near bulk-earth estimates along the MORB–oceanic island basalt (OIB) mantle array. The varieties in modal proportions of minerals, (La/Yb)_N ratio and Sr-Nd isotopes for the xenoliths demonstrate that the lithospheric mantle beneath Jeju Island is heterogeneous. The heterogeneity is a probable result of its long-term growth and enrichment history.  相似文献