Age and Origin of Paleogene Granitoids from Western Yunnan Province, China: Geochemistry, SHRIMP Zircon Ages, and Hf-in-Zircon Isotopic Compositions     

SHI Yuruo  WU Zhonghai  Alfred KR?NER  FAN Taoyuan  YANG Zhenyu 《《地质学报》英文版》2015,89(5):1601-1615

We report geochemical data, SHRIMP zircon ages and Hf-in-zircon isotopic compositions for Cenozoic granitoids from major fault systems in the Tethyan belt in western Yunnan Province, southwestern China.Four magmatic pulses occurred in the Paleogene, namely at ca.57 Ma, ca.50 Ma, 45–40 Ma, and 38–34 Ma.Early magmatism of this episode(57–50 Ma) produced S-type granites whose zircons yielded εHf(t) values of-5.0 to-0.3.In contrast, late magmatism of this episode reflects heterogeneous sources.Zircons from a granite porphyry along the Ailaoshan-Red River fault system have slightly positive εHf(t) values suggesting derivation from relatively young crust and/or a juvenile source.However, zircons from a granite along the Gaoligong fault system have strongly negative εHf(t) values and suggest derivation from a Paleoproterozoic crustal source.The composition of the granitoids varies with age(from ca.57 Ma to ca.34 Ma) from peraluminous to metaluminous and also suggests a change from syn-collisional to late-orogenic tectonic setting.A new tectonic model, impacting lithospheric wedge(ILW) is shown for the origin of Paleogene granitoids in this paper.  相似文献   

Early Palaeozoic Deep Subduction of Continental Crust in the Kyrgyz North Tianshan: Evidence from Field Relationships and Geochronology     

KR?NER A  ROJAS-AGRAMONTE Y  HERWARTZ D  CORSINI M  ALEXEIEV D.V. 《《地质学报》英文版》2015,89(Z2):36-36

<正>High-and ultrahigh-pressure(UHP)eclogite-bearing metamorphic assemblages in the North Tianshan of Kyrgyzstan contain eclogite-bearing garnet amphibolites interlayered with phengite-beearing granitoid gneisses.The mafic rocks were previously interpreted as remnants of a Precambrianm ophiolite,but field relationships clearly  相似文献   

1999年度气象条件对农作物生长的影响     

张雪芬  刘荣花 《气象与环境科学》2000,(2):27-29

1　对小麦生产的影响1 .1　小麦生长期农业气象条件概述1 999年度河南省小麦生育期间总的气候特点是 :小麦播种时 ,降水量少 ,播种基础是近几年较差的一年 ;越冬至初春的降水仍偏少 ,气温异常偏高 ,干旱持续发展 ;拔节期间气温偏低 ,有效地抑制了小麦旺长 ;灌浆期大部麦区墒情较好 ,光照充足 ,气温适宜 ,有利于小麦灌浆。冬小麦全生育期降水 68～ 354ｍｍ ,比 1 998年同期偏少 4～ 8成 ,比常年同期偏少 1～ 7成 ,1 998年 1 0月至 1 999年 2月大部麦区降水特少 ,降水主要集中在 1 999年 3月份以后。其中大部分地市从 1 998年 9月～ 1 999年 2…  相似文献   

河南气候变化对水资源的影响及对策   总被引：3，自引：0，他引：3  

刘军臣  刘荣花 《气象与环境科学》2000,(4):23-24

分析了近５０年来河南气候变化的基本特点及气候变化对地表、地下水资源和农业旱涝灾害发生频次、强度的影响,并根据多模式预测结果,对未来３０年气候情景下河南水资源的供需状况进行了展望和评估。  相似文献   

以氚作为指示剂测量威斯康星州中部地区地下水的年龄     

Brad.  KR 钟文 《地质地球化学》1992,(4):75-79

  相似文献   

氚—威斯康星州中部地下水年龄的指示剂     

Brad.  KR 王佩仪 《地质科学译丛》1993,10(1):76-82

  相似文献   

西伯利亚变质火山—沉积岩型块状Pb—Zn硫化物矿床的地质背景和成因     

Kova.  KR 白冶 《国外矿床地质》1995,(4):67-67

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干旱及灌溉对冬小麦根系和产量的影响研究   总被引：1，自引：0，他引：1  

马青荣  刘荣花  胡程达  王红振  余辉  王艳玲 《气象》2020,46(7):971-981

在郑州农业气象试验站开展不同程度干旱、灌溉试验,研究了不同水分条件对冬小麦根系活力、形态及产量的影响。结果表明,干旱条件下,冬小麦根系活力和根直径均有明显的降低,根长有明显增加,土壤下层所占根系总体积比例增大,且随着发育期的推进,下层根系所占比例呈现增大的趋势,水分利用效率有明显提高;随着干旱程度的增加,上述变化趋势更加明显。在灌溉量相同的情况下,越冬期灌溉,有利于冬小麦根系活力和根直径增加,但不利于根系的向下伸展;返青期和拔节期灌溉有利于根系向下伸展、水分利用效率提高、理论产量增加,但不利于根系活力和直径的增加;拔节期灌溉,可适当增大灌溉量,减少灌溉次数,以提高水分利用效率。综合根系形态和活力、水分利用效率及产量,在冬小麦干旱持续发生条件下,在返青期、孕穗期灌水600 m~3·hm~(-2)左右,可根据干旱程度适当增减灌水量,重旱条件下适当增加灌水次数,少量多灌缓解旱情,而重大干旱年份灌水困难条件下可只在拔节期灌水600 m~3·hm~(-2),以实现产量的减损和节水效果。  相似文献   

Identifying potential marine pests--a deductive approach applied to Australia   总被引：4，自引：0，他引：4  

Hayes KR  Sliwa C 《Marine pollution bulletin》2003,46(1):91-98

Introduced marine organisms continue to threaten coastal resources around the world. Many agencies rely on lists of potentially harmful species for risk assessment and to prioritise management responses to an incursion. This study outlines a deductive hazard assessment technique to identify potential marine pests that may arrive via ballast water and/or hull fouling. This technique is then applied in an Australian context to identify potential "next pests" for this region. An extensive literature review identified 851 introduced marine species from around the world. The following selection criteria were then applied to develop a next pest list: (a) the species has been reported in a shipping vector or has a ship-mediated invasion history; (b) the vector still exists; (c) the species is responsible for economic or environmental harm; and, (d) it is exotic to Australia or present in Australia but subject to official control. The selection criteria are transparent and consistent with other international and national biosecurity initiatives. Thirty three of the species identified in the initial literature review satisfied all four selection criteria. These species are described here together with their associated vectors and impacts.  相似文献   

Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland   总被引：1，自引：0，他引：1  

Burow KR  Constantz J  Fujii R 《Ground water》2005,43(4):545-556

Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch.  相似文献