RETRACTED ARTICLE: Soil nutrient bioavailability and nutrient content of pine trees (Pinus thunbergii) in areas impacted by acid deposition in Korea     

Jae E. Yang  Wi-Young Lee  Yong Sik Ok  Jeffrey Skousen 《Geochemistry International》2008,46(9):951-957

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Timing of UHP metamorphism in the Hong’an area,western Dabie Mountains,China: evidence from zircon U–Pb age,trace element and Hf isotope composition     

Yuan-Bao Wu  Shan Gao  Hong-Fei Zhang  Sai-Hong Yang  Wen-Fang Jiao  Yong-Sheng Liu  Hong-Lin Yuan 《Contributions to Mineralogy and Petrology》2008,155(1):123-133

The Hong’an area (western Dabie Mountains) is the westernmost terrane in the Qinling-Dabie-Sulu orogen that preserves UHP eclogites. The ages of the UHP metamorphism have not been well constrained, and thus hinder our understanding of the tectonic evolution of this area. LA-ICPMS U–Pb age, trace element and Hf isotope compositions of zircons of a granitic gneiss and an eclogite from the Xinxian UHP unit in the Hong’an area were analyzed to constrain the age of the UHP metamorphism. Most zircons are unzoned or show sector zoning. They have low trace element concentrations, without significant negative Eu anomalies. These metamorphic zircons can be further subdivided into two groups according to their U–Pb ages, and trace element and Lu–Hf isotope compositions. One group with an average age of 239 ± 2 Ma show relatively high and variable HREE contents (527 ≥ Lu_N ≥ 14) and ¹⁷⁶Lu/¹⁷⁷Hf ratios (0.00008–0.000931), indicating their growth prior to a great deal of garnet growth in the late stage of continental subduction. The other group yields an average age of 227 ± 2 Ma, and shows consistent low HREE contents and ¹⁷⁶Lu/¹⁷⁷Hf ratios, suggesting their growth with concurrent garnet crystallization and/or recrystallization. These two groups of age are taken as recording the time of prograde HP to UHP and retrograde UHP–HP stages, respectively. A few cores have high Th/U ratios, high trace element contents, and a clear negative Eu anomaly. These features support a magmatic origin of these zircon cores. The upper intercept ages of 771 ± 86 and 752 ± 70 Ma for the granitic gneiss and eclogite, respectively, indicate that their protoliths probably formed as a bimodal suite in rifting zones in the northern margin of the Yangtze Block. Young Hf model ages (T _DM1) of magmatic cores indicate juvenile (mantle-derived) materials were involved in their protolith formation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Metallographic cooling rates and origin of IVA iron meteorites     

Jijin Yang  Joseph I. Goldstein 《Geochimica et cosmochimica acta》2008,72(12):3043-3061

We have determined the metallographic cooling rates for 13 IVA irons using the most recent and most accurate metallographic cooling rate model. Group IVA irons have cooling rates that vary from 6600 °C/Myr at the low-Ni end of the group to 100 °C/Myr at the high-Ni end of the group. This large cooling rate range is totally incompatible with cooling in a mantled core which should have a uniform cooling rate. Thermal and fractional crystallization models have been used to describe the cooling and solidification of the IVA asteroid. The thermal model indicates that a metallic body of 150 ± 50 km in radius with less than 1 km of silicate on the outside of the body has a range of cooling rates that match the metallographic cooling rates in IVA irons in the temperature range 700-400 °C where the Widmanstätten pattern formed. The fractional crystallization model for Ni with initial S contents between 3 and 9 wt% is consistent with the measured variation of cooling rate with bulk Ni and the thermal model. New models for impacts in the early solar system and the evolution of the primordial asteroid belt allow us to propose that the IVA irons crystallized and cooled in a metallic body that was derived from a differentiated protoplanet during a grazing impact. Other large magmatic iron groups, IIAB, IIIAB, and IVB, also show significant cooling rate ranges and are very likely to share a similar history.  相似文献   

Background concentrations of elements in surface soils and their changes as affected by agriculture use in the desert-oasis ecotone in the middle of Heihe River Basin,North-west China   总被引：1，自引：0，他引：1  

Yong-zhong Su  Rong Yang 《Journal of Geochemical Exploration》2008

The concentrations of twenty four chemical elements in the surface layer of natural desert soils and the cultivated farmland soils were measured at a desert-oasis ecotone in the middle of Heihe river basin, north-west China. Background values were estimated for (a) major elements (Si 335.3 g kg^− 1, Al 49.4 g kg^− 1, Fe 19.1 g kg^− 1, Ca 29.4 g kg^− 1, Mg 8.9 g kg^− 1, K 20.1 g kg^− 1, Na 17.5 g kg^− 1 and P 0.338 g kg^− 1), (b) heavy metals and non-metals (Cr 55.8 mg kg^− 1, Mn 404.8 mg kg^− 1, Ni 17.7 mg kg^− 1, Cu 5.1 mg kg^− 1, Zn 33.7 mg kg^− 1, Pb 15.5 mg kg^− 1 and As 5.2 mg kg^− 1) and (c) other trace elements (Ti 2.0 mg kg^− 1, V 55.3 mg kg^− 1, Co 5.7 mg kg^− 1, Rb 82.4 mg kg^− 1, Sr 232.9 mg kg^− 1, Y 14.7 mg kg^− 1, Zr 194.9 mg kg^− 1, Nb 7.8 mg kg^− 1 and Ba 720.6 mg kg^− 1). After natural desert soil was cultivated for agricultural use, significant changes in element concentrations occurred under tillage, irrigation and fertilisation management. Compared to natural soil, the for the levels of Si, K, Na, Sr, Zr and Ba decreased, and no changes were observed for Rb, while the values of the other 17 elements increase in agricultural soil from 1.2 to 3.5 times. However, their absolute concentrations are still low, suggesting that the arable soil in this region remains comparatively a clean soil. The increased silt, clay and organic carbon content, under long-term irrigation, enriched the fine-grained materials, and application of fertilisers and manure contributed to the accumulation of most elements in arable soil. The accumulation of elements in agricultural soil increased with increasing cultivation years and extent of soil development.  相似文献   

碳酸盐岩裂缝与岩溶作用研究   总被引：12，自引：2，他引：10  

艾合买提江·阿不都热和曼  钟建华  李阳  钟富平  高玉飞 《地质论评》2008,54(4):485-493

从构造与非构造作用角度出发,突出研究断层对裂缝的控制作用、断裂与岩溶的关系和裂缝与岩溶之间的关系,揭示碳酸盐岩裂缝与岩溶的发育规律。研究表明：构造裂缝为岩溶发育提供岩溶作用进行的有利通道,非构造裂缝则可以加速溶蚀作用的进行,促进岩溶的发育;裂缝与岩溶之间的关系始终是相辅相成、相互促进的关系。  相似文献   

牛庄洼陷沙河街组超压系统发育特征及其演化   总被引：1，自引：0，他引：1       下载免费PDF全文

李阳  王建伟  赵密福  高侠 《地质科学》2008,43(4):712-726

东营凹陷牛庄洼陷沙河街组发育有超压系统,这对油气运移和聚集过程有着重要的影响。在对超压系统现今发育特征研究的基础上,本文运用约束下数值模拟方法对牛庄洼陷超压系统的演化规律进行研究,并探讨了超压系统的主要形成机制。牛庄洼陷在沙河街组四段、沙河街组三段的下亚段和中亚段存在着超压系统,最大压力系数可以达到1.8,最大剩余压力超过了20MPa。自沙三段上亚段沉积期开始,超压系统开始发育。到东营组沉积期末,超压系统经历了大约10Ma的泄压过程。自新近系馆陶组沉积期,超压系统再次迅速增压,逐渐接近现今发育状况。上覆地层沙三段上亚段高沉积速率导致了超压系统的形成和早期剩余压力的增加,而水热增压和烃类物质大量生成联合造成超压系统晚期迅速增压。超压系统演化规律揭示出在油气主要运移期研究区古异常流体压力的分布状况,这为进一步开展牛庄洼陷油气运移和聚集过程的动力学研究提供了理论依据。  相似文献   

库车坳陷大北地区下白垩统巴什基奇克组储层成因地质分挝   总被引：6，自引：0，他引：6       下载免费PDF全文

张荣虎  张惠良  寿建峰  沈扬  李昌 《地质科学》2008,43(3)

塔里木盆地库车坳陷大北地区白垩系巴什基奇克组储层以细一中粒岩屑砂岩为主夹少量长石岩屑砂岩,杂基为铁泥质和泥质(2%～10%).胶结物以方解石(3%～15%)为主.粘土矿物以伊利石、绿泥石和伊/蒙混层为主,不含高岭石,伊/蒙混层中的蒙皂石含量一般为(15～20)%;主要孔隙组合为残余原生粒问孔-溶蚀孔-微孔隙,占储集空间总量的(50～90)%,其次为构造缝-溶蚀孔,主要的孔隙类型为溶蚀孔和裂缝,总体属于低孔低渗-特低孔特低渗储层.综合分析认为:阶段性的前陆构造逆冲推覆作用对沉积旋回性、水体盐度变化及物源区距离变化的控制至关重要;构造活跃期扇三角洲前缘环境中形成的差分选中-粗砂岩、近源快速堆积造成的高岩屑含量、干旱成湖导致的高碳酸盐胶结和早成岩期相对深埋-后期持续快速深埋压实作用,是特低孔特低渗储层的主要成因;而较优质储层足构造平缓期辫状河三角洲前缘环境中形成的分选好的中-细砂岩、早期表生溶蚀及弱碳酸盐胶结作用、早期构造破裂的复合作用及其叠加效应的结果.  相似文献   

北疆阿尔泰南缘泥盆系浅变质碎屑沉积岩地球化学特征及其形成环境   总被引：12，自引：4，他引：8  

龙晓平  袁超  孙敏  肖文交  林寿发  王毓婧  蔡克大 《岩石学报》2008,24(4)

对于北疆阿尔泰地区泥盆纪所处的大地构造环境,目前仍旧存在不同观点。前人基于阿尔泰南缘泥盆纪火山岩地球化学研究,分别提出了活动大陆边缘和被动大陆边缘裂谷等不同构造观点。阿尔泰造山带南缘的泥盆纪浅变质碎屑沉积岩地球化学研究表明,该套浅变质碎屑沉积岩原岩主要为泥质或砂质沉积岩。尽管不同岩性样品主量元素含量不同,但其化学蚀变指数(CIA)小于75,成分变异指数(ICV)接近或小于1.0,斜长石蚀变指数(PIA)平均70,说明其源区物质比较新鲜,成熟度相对较低,化学风化作用较弱。同样,不同岩性样品微量元素含量差别较大,但表生过程中不活泼的微量元素比值却比较一致,轻稀土(LREE)中度富集(La_N/Yb_N=2.88～9.90),重稀土(HREE)比较平坦,并伴有明显的Eu负异常(Eu/Eu~*= 0.45～0.89)。绝大多数样品具有高的La/Sc(1～3)、La/Y(0.5～1)和Ti/Zr(10～35),以及较低的Sc/Cr(0.1～0.3)比值,类似于大陆岛弧相关环境碎屑沉积物。在La-Th-Sc和Th-Sc-Zr/10构造环境判别图解中,除一千枚岩样品外,其他所有样品均落入大陆岛弧区。以上地球化学特征明显不同于大洋岛弧和被动陆缘沉积物,说明该套浅变质碎屑沉积岩可能沉积于活动大陆边缘的大陆岛弧相关环境,为认识阿尔泰造山带泥盆纪岛弧增生构造演化过程提供了一个重要证据。  相似文献   

水库库岸滑坡涌浪的传播与爬高研究   总被引：5，自引：0，他引：5  

汪洋  殷坤龙 《岩土力学》2008,29(4):1031-1034

基于流体力学明渠非恒定流的连续性方程、运动方程和沿程水头损失理论,把滑坡涌浪衰减过程分为急剧衰减和缓慢衰减两个阶段来考虑,并认为急剧衰减阶段的涌浪的衰减符合指数衰减规律,缓慢衰减阶段符合明槽水流的沿程水头损失规律,结合初始涌浪高度对涌浪沿岸的传播高度及爬坡高度进行了计算。以新滩滑坡为例对涌浪的传播及爬坡高度进行了计算,得出了滑坡涌浪衰减先快后慢以及传播3 km时的涌浪高度只有初始涌浪高度的30 %以及传播10 km时涌浪高度只有初始涌浪高度的13 %的规律。  相似文献   

大凌河流域河道生态需水量估算   总被引：1，自引：0，他引：1  

齐悦  卢文喜 《水文》2008,28(4)

本文从大凌河流域存在的环境问题出发,分别估算了各水资源分区的河道生态需水量（包括生态基流量、自净需水和输沙需水）及各区的河道生态需水贡献量。提出了使用偏枯年（75％保证率）水文数据估算河道生态需水量的方法．弥补了Tennant法、枯水季最小流量法等方法计算结果偏大或偏小的不足。结果表明,大凌河的4个河段（建凌站以上、建凌站至朝阳站、朝阳站至义县站、义县站至锦县段）的河道分区需水量分别为0．55×10^8m^3、5．21×10^8m^3、3．9×10^8m^3和1．34×10×10^8m^3。锦县水文站以上河道生态需水总量11×10^8m^3,占地表水总资源量的59．75％,因此．大凌河地表水资源取用率应在40％以下。  相似文献