小流域水土资源优化配置线性规划数学模型的构建及求解——以陕南丹凤大南沟小流域为例     

任金来  李云峰  王玉喜 《江苏地质》2019,43(1):122-128

陕南地区位于秦岭山区,坡耕地面积大,降雨形成的坡面径流是当地水土流失的主导因子,通过合理配置当地土地资源,充分利用坡面径流资源,从而减少水土流失。以陕南大南沟小流域为研究对象,通过收集整理当地多年的降雨资料,借助GIS及Surfer等相关软件对不同坡度的坡地资源进行划分和统计,利用流域内水土资源之间的相互依存及彼此约束性,基于线性规划理论,通过构建、求解水土资源优化配置线性规划的数学模型,对小流域的水土资源进行优化配置,并用单纯形法对模型进行求解。通过对模型中相关参数的不断优化、调节,最终得出“以人定水田”“以水定田无旱无树”“以水定田无旱有树”3种水土资源的优化配置方案。通过优化配置即可达到水土保持的目的,同时也为后期土地规划等提  相似文献   

丹凤群斜长角闪岩中角闪石的环带及变质作用     

胡能高  安三元  杨家喜  李荣西 《地球科学与环境学报》1992,(1)

在丹凤群中,部分斜长角闪岩含有由阳起石内核和镁普通角闪石外环组成的环带角闪石。外环形成于主变质期,而内核是早期变质矿物的残余。早期变质作用属低压相系的斜长石-阳起石相环境,发生在丹凤群形成之初;而主期变质发生在加里东晚期的中压相系的角闪岩相。大约在海西—印支期后又出现了伴随韧性剪切作用的退变质现象。早期变质和主期变质作用可能分别与秦岭造山带的裂谷作用和裂谷闭合过程有关。  相似文献   

Geochronology and geochemistry of the Heihe mafic pillow lavas in the Qinling Mountains, China     

张宗清  张国伟  唐索寒  王进辉 《中国科学D辑(英文版)》2001,44(6):517-524

The Qinling Mountains in central China are the joint orogenic zone between the Sino-Korean (or North China) and the Yangtze craton blocks. The age and genesis of the Danfeng mafic volcanics in the north of the Shangzhou-Danfeng fault zone, i.e. the main suture zone in the Qinling orogenic belt, have been controverted for a long time because their age is closely related to the converged time of two blocks. The ages and the geochemical data of the Heihe pillow lavas for the Danfeng mafic volcanics in the Heihe River area in the Qinling orogen are reported in this paper. The obtained isochron age by the Sm-Nd isotopic data of the 13 whole-rock samples for the mafic pillow lavas is 963±130 (2σ) Ma, corresponding to I_Nd = 0.51173±16 (2σ),ɛ _Nd(T)= +6.6, MSWD0.57. However, the Rb-Sr isotopic analytical results for the same samples as the Sm-Nd whole-rock ones are disperse. For the Sm-Nd isotopic systems were interfered during the later geological functions, the Sm-Nd isochron age for the whole-rock sample (Q9511WR) and the mineral phenocrystal samples: amphiboles (Hb) and plagioclases (Plag) presents the better uncertainty, whereas isochron ages of 930 Ma and 437 Ma are given if the WR-Plag and WR-Hb are calculated respectively, and their Rb-Sr isochron age is 268±47(2σ) Ma, I_sr = 0.70475±11 (2σ), MSWD0.96. The major and trace elements for the lavas show that they were formed in the quasi-N-MORB setting.  相似文献   

秦岭丹凤群蛇绿岩古地磁学再研究   总被引：3，自引：0，他引：3       下载免费PDF全文

吴汉宁  陈岩 《地球物理学报》1992,35(3):361-368

本文是对秦岭丹凤县桃花铺郭家沟剖面和商县三十里铺剖面丹凤群蛇绿岩标本的古地磁学研究结果.逐步热退磁和剩磁方向主分量分析表明,60％以上的标本含有可明显区分的3个剩磁组分.另外的约30％-40％的标本,尽管它们具有很高的天然剩磁强度,在150-200℃时,其剩磁强度即衰减50％以上,且显示出不稳定的方向.两种不同的磁性表现与不同的岩石组成和结构有关,特别是与岩石的结晶程度有关.经对3个剩磁组分成因的分析及与变质变形关系的研究,表明高温剩磁组分是原生.由高温剩磁组分得到丹凤群古地磁极位置为43.0°N,274.5°E,古纬度值为12.0°S.比较丹凤群的古地磁极位置和华北扬子块体古地磁极移曲线,发现它们之间存在显著差异,这表明丹凤群在古生代不从属于华北或扬子块体,而是一个独立的地体,很可能是秦岭古洋壳的残片,从而给丹凤群蛇绿岩赋予新的大地构造含义.  相似文献   

柞水北部秦岭群中丹凤岩群和龙潭子序列的确立   总被引：5，自引：1，他引：4  

崔建堂  赵长缨  计文化 《陕西地质》1999,(1)

通过对柞水地区北部秦岭群分布区进行1：．5万区调填图,从前人划分的古元古代秦岭群中解体出丹凤岩群和一套中酸性侵入体,并从岩石化学、地球化学、稀土元素、同位素等方面进行了初步研究。同时在丹凤岩群中获得Rb－Sr同位素等时线年龄为444±29Ma,在中酸性侵入岩体中获得错石U－Pb同位素等时线年龄为407±19Ma。为研究丹凤岩群时代归属提供了新的资料。  相似文献   

甘肃天水地区丹凤群变质火山岩地质地球化学特征及其构造环境研究   总被引：2，自引：0，他引：2  

梁自兴 《甘肃地质》1994,3(1):71-78

丹凤群是分布在北奏岭南侧重要的早古生代地层。其火山岩以基性玄武岩为主，另有部分中性安山岩及少量酸性流纹岩。岩石组合、岩石化学及地球化学特征指示其为早古生代不成熟的初始岛弧环境。  相似文献   

Zircon U-Pb and geochemical analyses for leucocratic intrusive rocks in pillow lavas in the Danfeng Group,north Qinling Mountains,China   总被引：1，自引：0，他引：1  

Yan QuanRen  Chen JunLu  Wang ZongQi  Yan Zhen  Wang Tao  Li QiuGen  Zhang ZongQing  Jiang ChunFa 《中国科学D辑(英文版)》2008,51(2):249-262

Field observation showed that there are many irregular leucocratic intrusive rocks in pillow lavas in the Danfeng Group in the Xiaowangjian area, north Qinling orogenic belt. Photomicrographs indicated that the protoliths of those altered leucocratic intrusive rocks are dioritic rocks. Geochemical analyses showed that pillow lavas have a range of SiO2 from 47.35% to 51.20%, low abundance of TiO2 from 0.97% to 1.72%, and percentages of MgO (MgO#=41―49). Chondrite-normalized REE patterns of pillow lavas are even, indicative of a weak differentiation between LREE and HREE (La/YbN=1.52―0.99). N-MORB-normalized trace element abundances showed that pillow lavas are enriched in incompatible elements (e.g., K, Rb, and Ba). Leucocratic intrusive rocks in pillow lavas have a wide range of SiO2 from 53.85%―67.20%, low abundances of TiO2 from 0.51%―1.10%, and MgO (MgO#=40―51), and higher percentages of Al2O3 (13.32%―16.62%) and concentration of Sr (342-539 μg/g), ratios of Na2O/K2O (2―7) and Sr/Y (17―28). Chondrite-normalized REE patterns of leucocratic intrusive rocks showed highly differentiation between LREE and HREE (La/YbN=12.26―19.41). N-MORB-normalized trace element abundances showed that leucocratic intrusive rocks are enriched in incompatible elements (e.g., K, Rb, and Ba), and significantly depleted in HFSE (e.g., Nb, Ta, Zr and Ti), indicative of a relationship to subduction. Isotopically, leucocratic intrusive rocks have a similar εNd(t) ( 7.45― 13.14) to that of MORB ( 8.8― 9.7), which indicates that those leucocratic intrusive rocks sourced from depleted mantle most likely. SHRIMP U-Pb analyses for zircon showed that those leucocratic intrusive rocks were formed at 442±7 Ma, yielding an age of subduction in the early Paleozoic in the north Qinling orogenic belt.  相似文献