Late Quaternary Paleoclimatic Change in the Ulleung Basin, East Sea, Korea

Paleoclimatic changes in the late Quaternary sediments deposited in the East Sea were analyzed by studying diatoms. A total of 95 species belonging to 47 genera were identified from the Core02GHP-02 of the Ulleung Basin in the East Sea, Korea. In the Core 02GHP-02, U-Oki(169–181 cm; 9.3 ka), AT(464–465.5 cm; 22 ka) and U–Ym(556–559 cm; 33 ka) tephra layers were recognized. The chronological divisions of 02GHP-02 may be correlated with the climatic changes from the glacial interval(730–620 cm; MIS3), to interstadial(620–500 cm; MIS3), to the last glacial maximum(500–390 cm; MIS 2), to the deglaciation(390–290 cm; MIS 2), to the late glacial(290–190 cm; MIS 1), and to the Holocene(190–10 cm; MIS 1). It is speculated that diatoms were rarely found during the glacial interval when the 02GHP-02 core was deposited; during the interstadial(MIS 3) and deglaciation, a mixture of warm-water and cold-water species were found. In particular, Fragilariopsis doliolus seems to have appeared in the East Sea after 8 ka BP. In the lower layers of the Holocene deposits, cold-water species such as Neodenticula seminae were frequently found, while in the upper layers, warm-water species such as Hemidiscus cuneiformis were found in relatively large abundance. Therefore, the findings indicate that the climate became warmer during the transition from the lower layer to the upper layer of the Holocene deposits.     

汶川地震区地壳上地幔三维S波速度结构初步研究

2008年5月12日汶川MW7.9地震发生在龙门山断裂带。龙门山断裂带及其邻域的地壳上地幔三维速度结构的研究对于理解汶川大地震的动力学背景具有重要的意义。2006年10月至2009年10月,在国家重大基础研究项目(973)的支持下,中国地震局地质研究所地震动力学国家重点实验室在川西地区(26°~32°N,100°~105°E)布设了由297台宽频带数字地震仪组成的流动观测台阵(简称川西台阵)。根据川西台阵记录的环境噪声和远震波形数据,利用噪声成像技术和接收函数方法,我们研究了川西地区(29°~32°N,100°~105°E)地壳上地幔100km深度范围内的三维S波速度结构。本文得到的结果为研究川西高原和四川盆地的地壳结构提供了新的高分辨率观测证据。我们的结果表明:1)观测台阵覆盖的川滇地块、松潘-甘孜地块和四川盆地的地壳上地幔S波速度结构具有显着差异,龙门山断裂和鲜水河断裂带,作为地块间的边界断裂带,对两侧地壳结构具有明显的控制作用。2)观测台阵覆盖区域的地壳厚度存在明显差异,川滇地块的地壳厚度为60~64km,松潘-甘孜地块的地壳厚度为52~56km,四川盆地前陆的地壳厚度为46~52km,沿龙门山断裂带松潘-甘孜地块和四川盆地形成镶嵌结构,汶川地震震中处南北两侧的壳幔边界存在约6km的断错。3)四川盆地前陆低速特征表明相应区域存在厚度8~10km的沉积盖层,松潘-甘孜地块和川滇地块的中下地壳具有大面积分布的S波低速区,松潘-甘孜地块地壳平均泊松比高达0.29~0.31,汶川地震余震绝大多数分布在低速区上方的高速介质区域内,而四川盆地的中下地壳呈现整体性的高速特征,以汶川地震的震中为界,龙门山断裂带北段和南段的S波速度结构显示了明显的速度分段特征,其北段的S波速度总体上高于南段。4)本文给出的研究区地壳三维S波速度结构表明,川西高原中下地壳较为软弱,而四川盆地中下地壳的强度应明显高于松潘-甘孜地块,意味着四川盆地坚硬中下地壳可以阻挡松潘-甘孜地块向东的逃逸;另一方面,川西高原和川滇地块的中下地壳虽然均存在大面积的S波低速区,但松潘-甘孜地块内的地壳速度结构相对来说较为复杂,并形成了高、低速相间的结构特征,表明在四川盆地的阻挡作用下,该地块形成了折皱变形的结构。5)与S波低速区相应,松潘-甘孜地块和川滇地块中下地壳应处于部分熔融的状态,这对该区域存在中下地壳通道流(Channelflow)的推断是一个支持;但是,松潘-甘孜地块内是否存在中下地壳通道流仍有待进一步的深入研究。6)接收函数方位各向异性的偏振分析表明,以汶川地震震中为界,龙门山断裂西南侧处于挤压状态,而其东北侧的主压应力方向与断层走向大体平行,推断先存应力场可能驱动了汶川地震逆冲破裂之后沿龙门山断裂向北东方向的走滑破裂。     

贡嘎山快速隆升的磷灰石裂变径迹证据及其隆升机制讨论

鲜水河断裂是青藏高原东南缘的一条北西向大型左旋走滑断裂,其南东段逐渐向南偏转,并与近南北向的安宁河断裂相接,在两个断裂相接处西侧耸立着海拔7556 m高的贡嘎山.磷灰石裂变径迹(AFT)测试可知,贡嘎山及其邻区12个样品的年龄分布在0.2±0.1 Ma~2.7±0.7 Ma之间,平均径迹长度在13.64~15.19 μm之间,表明贡嘎山及其邻区第四纪时期一直处于快速剥蚀状态.结合前人在此地区的低温热年代研究成果,揭示出两个现象:(1)贡嘎山岩体及鲜水河断裂与龙门山断裂所夹的三角区域为快速隆升区域,而其西侧、北侧的高原腹地的隆升速率远低于这两个区域;(2)贡嘎山岩体从北向南隆升速率逐渐变大,其最南端1 Ma以来的隆升速率超过3.3±0.8 mm/a.这些现象表明青藏高原在整体横向挤出、缓慢隆升的基础上,还存在着一些特殊的局部快速隆升区域.通过对川滇地块水平运动的矢量分解,我们认为贡嘎山花岗岩体是鲜水河断裂至安宁河断裂间挤压弯曲段吸收、转换川滇地块南东向水平运动导致局部快速隆升的产物,在这一过程中,由于垂直于断裂的挤压分量从北到南逐渐增大,导致了岩体从北往南的隆升速率逐渐增大.     

Observational Study of Surface Wind along a Sloping Surface over Mountainous Terrain during Winter

The 2018 Winter Olympic and Paralympic Games will be held in Pyeongchang, Korea, during February and March. We examined the near surface winds and wind gusts along the sloping surface at two outdoor venues in Pyeongchang during February and March using surface wind data. The outdoor venues are located in a complex, mountainous terrain, and hence the near-surface winds form intricate patterns due to the interplay between large-scale and locally forced winds. During February and March, the dominant wind at the ridge level is westerly; however, a significant wind direction change is observed along the sloping surface at the venues. The winds on the sloping surface are also influenced by thermal forcing,showing increased upslope flow during daytime. When neutral air flows over the hill, the windward and leeward flows show a significantly different behavior. A higher correlation of the wind speed between upper-and lower-level stations is shown in the windward region compared with the leeward region. The strong synoptic wind, small width of the ridge, and steep leeward ridge slope angle provide favorable conditions for flow separation at the leeward foot of the ridge. The gust factor increases with decreasing surface elevation and is larger during daytime than nighttime. A significantly large gust factor is also observed in the leeward region.     

Effects of an Urban Park and Residential Area on the Atmospheric CO2 Concentration and Flux in Seoul, Korea

The CO₂ concentrations and fluxes over an urban forest site (Namsan) and an urban residential region (Boramae) in Seoul, Korea, during the non-growing season (2–4 March 2011), the growing season (10–12 June 2011), and the late-growing season (22–24 September 2011) were analyzed. The CO₂ concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season (early spring) and a minimum value during the growing season (summer). The CO₂ flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO₂ flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600–1000 LST and 1800–2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.     

中东亚地区表土碳酸盐含量和pH值的空间变化及其气候代用指标意义

黄土-古土壤以及湖泊沉积物的碳酸盐含量作为常用的气候指标,被人们广泛地应用于干旱、半干旱地区的古气候研究,然而碳酸盐含量的气候意义却缺乏足够的验证.中东亚干旱、半干旱区覆盖我国西北部和蒙古国全境,区域内温度和降水等具有显著的空间分布特征,这为验证包括碳酸盐矿物含量在内的地球化学代用指标的气候意义提供了理想的研究场所.为此,选取了一条横跨该区不同气候带的采样线,对采样线上表土碳酸盐含量、pH值以及气象站的记录资料行了分析和对比.研究发现:(1)表土碳酸盐含量的分布特征沿着纬度呈现出南高北低的总体趋势,在北纬34.50°～42.50°的广大黄土、类黄土地区,碳酸盐含量较高,而北纬42.5°以北地区碳酸盐含量则相对较少,局部地区由于土壤母质为碳酸盐岩而具有较高的碳酸盐含量;(2)表土碳酸盐含量与pH值的非线性拟合特征反映出土壤碳酸盐矿物含量与pH值之间的化学平衡,两者在0.01水平上呈显著的正相关关系(r=0.51).酸性土壤地区的碳酸盐体系难处于饱和状态,碳酸盐易于淋失含量低,此时,碳酸盐矿物含量不宜作为气候指标,而碱性土壤地区的碳酸盐矿物含量变化与气候变化关系密切;(3)高温、干燥的气候环境使降水被迅速蒸发,加剧了碳酸盐类物质的表聚作用,使黄土、类黄土地区表土碳酸盐含量与降水量、温度都呈现出了一定的正相关关系;(4)黄土、类黄土地区表土pH值与多年平均降水量关系密切(PH>7,R2=0.90),可以作为我国黄土高原地区过去大气降水量变化的代用指标.     

澳大利亚南极科学数据管理综述

系统概述了澳大利亚国家南极数据政策、组织机构、管理模式、实施策略与未来发展所面临的问题。在此基础上分析澳大利亚南极数据工作的发展与实效,并回顾了中国的极地数据管理工作,初步表明建立一个有效的组织框架是顺利开展数据管理与共享工作的基础,完全基于Web的数据管理与服务对科学项目的管理与研究成果的产出具有较大的促进作用。同时可以看出,国家层面的数据管理工作首先必须有明确的国家数据政策作引导;需要建立各种相应的数据标准与规范以及基于Web的数据管理、共享与服务平台;当然更离不开一支进行数据管理、服务与技术支持的专业队伍,并通过工作绩效评价系统对各个环节进行评价和考核。其中,为数据（集）编写完整、准确的元数据始终是数据管理中最重要的基础工作。     

安徽铜陵地区中酸性侵入岩及其岩石包体中的矿物包裹体研究

铜陵地区是长江中、下游铁、铜、硫、金成矿带的重要组成部分。笔者对铜陵地区中酸性侵入岩及其岩石包体中的包裹体进行了较系统的岩相学、显微测温和激光拉曼光谱研究。通过岩相学观察发现了 3类包裹体 ,即晶质熔融包裹体、流体熔融包裹体和流体包裹体。显微测温资料表明 ,本区的岩浆流体成矿演化可分为 3个阶段 :岩浆阶段 ( >12 5 0～ 90 0℃± )、过渡岩浆阶段 ( 90 0～ 75 0℃± )和岩浆期后热液阶段 ( <75 0℃ )。部分熔浆的温度之高 (可达 12 5 0℃ ) ,表明其可能是底侵幔源岩浆同熔下地壳形成的。在老庙基岩体、小铜官山岩体、鸡冠石岩体和小陶家岩体中产有晶质熔融包裹体、流体熔融包裹体和流体包裹体这 3种包裹体 ,表明相应的岩浆流体演化具有连续性、继承性和阶段性 ,其对应的成矿溶液以岩浆热液为主 ;与此不同的是 ,在鸡冠山岩体和白芒山岩体中仅产有晶质熔融包裹体和流体包裹体两种类型的包裹体 ,表明相应的岩浆流体演化不具连续性 ,其对应的成矿溶液以天水热液为主。此外 ,在小铜官山岩体和鸡冠石岩体的中酸性侵入岩中 ,发现了不混溶包裹体 ,其可能是在压力释放条件下形成的。     

Melt Enrichment of Shallow Depleted Mantle: a Detailed Petrological, Trace Element and Isotopic Study of Mantle-Derived Xenoliths and Megacrysts from the Cameroon Line

Major element, trace element and Sr–Nd–Pb isotopiccompositions of ultramafic xenoliths and megacrysts from thecontinental Cameroon line provide evidence for metasomatismof the upper most lithospheric mantle by enriched melts duringthe Mesozoic The megacrysts probably crystallized within thelower continental crust from melts similar to the host magmas.All the xenoliths originated as depleted residues after theextraction of basaltic melts, but some indicate evidence ofinteraction with enriched partial melts before entrainment.The U–Pb isotopic data on garnet are consistent with coolingthrough >900C at >300 Ma. The Sm–Nd isotope systematicsin constituent phases appear to have been in equilibrium ona xenolith scale at the time of entrainment, indicating derivationfrom mantle that remained at temperatures >600C until eruption.Spinel therzolies that show simple light rare earth element(LREE) depletions are characterized by isotopic compositionsthat are comparable with, but slightly more depleted than AtlanticN-MORB, suggesting that the unmetasomatized sub-continentallithosphere of the Cameroon line may be isotopically similarto that of sub-oceanic lithosphere. The Nd-depleted mantle modelages of these xenoliths are consistent with late Proterozoicdepletion, similar in age to much of the overlying continentalcrust. In contrast, samples that have LREE-enriched clinopyr-oxenes(La/Yb =4.7–9.4) contain trace amounts of amphibole, areenriched in U and have more radiogenic Pb and Sr. These xenolithsyield U–Pb and Sm–Nd model ages consistent withMesozoic enrichment, in agreement with the age of enrichmentof the source regions of the basalts, as deduced from Pb isotopiccompositions. Clinopyroxenes record three orders of magnitudeenrichment in U and LREE accompanied by progressive K depletionassociated with the growth of trace amphibole, with K/U ratiosthat range from 12000 to 1. The ratios of the trace elementsthought to have similar bulk D in mantle melting, Ce/Pb, Ba/Rband Nd/Sr ratios, display regional variations related to thetime integrated history of enrichments indicated by Nd isotopiccompositions. Mass balance calculations suggest that the meltsresponsible for the most recent enrichment of the lithospherehad higher La/Yb and U/Pb than Cameroon line host magmas, andwere probably the product of small degrees of partial meltingassociated with the earliest stages of the breakup of Pangea. KEY WORDS: Cameroon line; mantle xenoliths; megacrysts; REE; isotopic composition; trace element     

二氧化碳储存环境对油井水泥性质影响之研究

二氧化碳存入地下以地质封存方式进行减量是一项可行的工程手段。干燥情况下二氧化碳基本没有危害。然而在进行地质封存时,气井通常在地下水层、盐水层等潮湿的环境下操作,二氧化碳与水结合会形成碳酸,形成一个酸性的环境。实验室将API G级油井水泥添加包括飞灰、膨润土、重晶石与硅粉,在潮湿(100%)、饱和二氧化碳（常压,70 ℃）环境条件下养护28 d,研究其力学性能、化学成分及微观结构之间的关系。试验项目包括抗压强度、微观结构分析、X射线衍射及EDS扫描电镜。观察其养护样品发现,API G级添加飞灰的水泥呈现出最佳抗压强度及最深的碳化深度。而API G级添加膨润土的水泥现出最低抗压强度及最浅的碳化深度