Comparison of net primary productivity in karst and non-karst areas: a case study in Guizhou Province,China

Green plants play an important role in energy flows and material cycles. The net primary productivity (NPP) reflects the capability of vegetation to convert solar energy into photosynthate (fixed carbon). Understanding the factors that contribute to variations in NPP is of key importance for improving the rock-desertification environment in karst areas. In this paper, the NPP model (Light Use Efficiency model) is modified on the basis of remote sensing data [moderate resolution imaging spectroradiometer (MODIS)], climate data and observed information. Then the model is employed to estimate the spatial–temporal variations of NPP in the Guizhou Province, China. Finally, the NPP differences between karst area and non-karst area, and the relationships between NPP and climate factors are analyzed. The results show that the NPP estimated using MODIS data are reasonable. The mean NPP of territorial vegetation is 421.46 gC m⁻² year⁻¹; the NPP in the non-karst area is 13.3% higher than that in the karst area; the correlation degree between NPP and precipitation is better in southeastern and western districts.     

贵州省喀斯特地区植被净第一性生产力的估算

在构建光能利用率模型的基础上,依托遥感手段,利用MODI S数据和气象资料,完成了贵州省喀斯特地区2001年植被净第一性生产力( N PP )的估算,并通过喀斯特地区与非喀斯特地区植被N P P 的对比,重点研究了喀斯特地区植被NP P 的时空变化特征,得到以下主要结论: ( 1)喀斯特地区与非喀斯特地区的植被N PP 在时空分布上存在明显差异,非喀斯特地区的N PP 平均值高出喀斯特地区约13. 3%。( 2)非喀斯特地区的N PP 频度分布呈似双峰型,而喀斯特地区的NP P 值似正态分布。( 3)年内植被N PP 的最高值和最低值均出现在7月和1月,但喀斯特地区比非喀斯特地区的整体波动性大。( 4)喀斯特地区植被N P P的季相空间变化显著,石漠化较为严重的地区其植被N P P 明显小于其它地区,且季间差异较明显。      

Spatial and temporal pattern of precipitation and drought in Gansu Province, Northwest China

Drought is one of the most harmful natural hazards in Gansu Province in Northwest China. The changes of precipitation affect the severity of drought. In order to recognize the trend of precipitation and understand the effect of rainfall change on water resources management and drought severity, Mann–Kendall test was used. Standardized Precipitation Index (SPI) was calculated to reconstruct the drought at different time scales and analyze the frequency of drought occurrence in the recent 50 years. The results show that the SPI is applicable in Gansu Province. The number of severe droughts differs among regions: it is more obvious as a 3-month drought in the Yellow River Basin and the Yangtze River Basin than in the Inland River Basin, and other droughts at 6-, 9-, and 12-month time scales have the same effect in the three regions. Mann–Kendall test results show that there is an upward trend in the summer periods and a downward trend in the autumn-winter-spring intervals ranging from 10.5 mm/10 years to −37.4 mm/10 years, which affect the local water resources management, droughts mitigation, and agriculture decision making. This situation poses challenges for future study.     

2000-2014年人类活动对贵州省植被净初级生产力的影响

利用MODIS实际净初级生产力数据与CASA模型估算得到的潜在净初级生产力,建立贵州省2000-2014年人类活动相对贡献指数（RCI）,并依据各县喀斯特地貌面积和等级比例探究其年际变化及空间分布特征,再通过相关分析辨析选定的人类活动因子对其的影响。结果表明：（1）贵州省RCI均小于-0.5,人类活动促进了植被净初级生产力的增加,以2007年为转折点,影响程度先增强后减弱;（2）贵州省东北部、中部及西部地区的RCI多大于0,人类活动对生态环境有负面干扰作用;东南部及北部边缘地带的RCI多小于-1,人类活动的正面影响较强;（3）贵州省中部、北部大部分地区的RCI缓慢下降,人类活动对植被的正面影响增强;东南部部分区域的RCI由负转正,人类活动负面干扰作用增强;西南边界地区的RCI呈上升趋势却仍为负值,人类干预程度呈减弱趋势;（4）贵州省农业活动在人类活动的负面影响中有重要作用;城镇化与经济发展对生态环境既有正面影响,也有不可避免的负面干扰。     

甘肃省金矿资源预测模型及潜力评价

为了更加科学有效地部署甘肃省金矿勘查找矿工作,必须对全省金资源总量作出定量预测,对省内各成矿带的金资源潜力作出定量评价。文章对甘肃省已发现的429处金矿床(点)的资料及全省1∶20万区域化探资料进行了统计和研究,建立了甘肃省金资源总量丰度估算模型、品位-储量回归预测模型及全省各成矿带金资源潜力分布模型。通过定量预测得知,甘肃省金资源总量的上限值为3166t,金资源总量为2420.6t;西秦岭成矿带的金资源潜力最大,占全省金资源潜力的37%,祁连成矿带次之,占24%,扬子成矿带占15%,北山成矿带占13%。据甘肃省岩金资源回归预测模型,岩金矿床在甘肃省具有极大的资源潜力。     

祁连山北缘旱峡早白垩世下沟组-中沟组沉积相研究

祁连山北缘旱峡地区发育完整的下白垩统下沟组-中沟组沉积序列;以陆源碎屑岩为主,发育砾岩、砂岩、钙质粉砂岩和页岩等;其中砾石分选差、磨圆一般、成分以灰白色砂岩为主,砂岩成分、结构成熟度中等-差。岩石组合、沉积序列和综合沉积特征研究表明,下沟组和中沟组主要由湖泊、扇三角洲、河流等3种类型沉积相、亚相与微相类型组成,发育了一系列重力流成因的沉积类型;湖泊沉积主要发育在下沟组底部和中沟组,扇三角洲沉积分布在下沟组中-上部,中沟组发育河流沉积。研究区早白垩世中期古流向以EN向为主,早白垩世晚期以W向为主,表明沉积沉降中心也由早期的旱峡西移至研究区西南侧。在综合分析的基础上,建立了研究区下白垩统下沟组-中沟组沉积相模式。     

Middle Permian Seamount from Xiahe Area, Gansu Province, Northwest China: Zircon U-Pb Age, Biostratigraphy and Tectonic Implications

The well-preserved seamount buildups are documented from the northwestern Qinling (秦岭) orogenic belts, Northwest China. The study sections are located in the Ganjia (甘加) area of the Xiahe (夏河) County, Gansu (甘肃) Province. The dark basalt and overlying massive reef carbonate characterize the Xiahe seamount buildup. Basalts are dominated by the olivine type of rocks and bear distinct porphyritic textures, and fumarole and amygdaloidal structures. The basaits are dominated by SiO2(up to 48.49 wt.%-52.29 wt.%) followed by (Na2O+ K2O) (3.80 wt.%-4.96 wt.%) and TiO2 (2.04 wt.%-2.52 wt.%). They are featured by considerably high content of Ti. The tholeilteseries rocks dominate the basalts, while calc-alkali-series rocks are also present. The REE of the basalts shows the LREE-enrichment type with distinct positive Eu abnormal. The trace elements of the basalts are characterized by the lack of P and high content of Ti. These geochemical signals suggest that the Xiahe basalts were formed in an ocean-island setting. The LA ICP-MS zircon U-Pb age of the basalts is 267.6±5 Ma, which is reinforced by the presnce of the fusuHnid Neoschwagerina Zone of the Wordian (Middle Permian) in the limestone interbeds of the basalts. Integration of petrological and geochemical studies of seamount basaits and lateral correlation of seamount buildups reveals that the Qinling-qilian-Kunlun orogenic belts were probably the archipelagtc oceans during the Permian.     

2000-2013年浑善达克沙地植被净初级生产力变化研究

利用卫星遥感资料和地面气象观测资料,基于CASA模型及其他数理方法估算了浑善达克沙地2000-2013年生长季（4-10月）植被净初级生产力（NPP）,并对其时空变化特征进行了分析,讨论了气候因子和人类活动对植被净初级生产力的影响。结果表明： 14年间,研究区生长季的植被净初级生产力呈波动中增加趋势,多年平均NPP为239.8 gC·m^-2·a^-1。整个研究区表现为高NPP值（大于150 gC·m^-2·a^-1）的植被面积在增加,低NPP值（小于150 gC·m^-2·a^-1）的植被面积在减少。在空间分布上,研究区的北部、中部和南部边缘区域的植被NPP增加趋势较明显,而东部和西部部分区域未发生明显的趋势性变化。总体而言,研究区植被净初级生产力变化趋势与降水量的关系更密切,其相关系数达到0.86,是驱动植被NPP年际波动的最直接因素。而与温度呈负相关,相关系数为-0.42。综合考虑气候因素和人类活动对沙地NPP的影响发现,温度降低、种饲料面积、年末牲畜存栏头数和羊的数量的减少是NPP值提高的关键因素。     

Exploring the effects of water on vegetation change and net primary productivity along the IGBP Northeast China Transect

To understand the mechanisms underlying the effects of climate variation, especially the effects of water on vegetation, vegetation type and distribution as well as climate data and soil type were used to simulate present vegetation distributions and net primary productivity (NPP) under present and future climate scenarios SRES-A2 and SRES-B2. A natural vegetation NPP model was also applied to calculate future vegetation NPP. The results showed that water played a dominant role not only in the distribution of vegetation, but also in the rate of change in the vegetation area. Analysis of NPP showed that precipitation had more effects on the amount of biome NPP than temperature did. Different effects were observed for the rate of change in NPP. In cases where biomes remain unaltered, the variation in annual precipitation could account for 39% of the variation in NPP. In cases where biomes changed, 45% of NPP was caused by temperature variation. Regarding the variation in transect production, −2.85% resulted from the change in vegetation structure when compared with present NPP, and 7.69% from the climate change under scenario SRES-B2; these values were −7.4 and 19.56%, respectively, under scenario SRES-A2. The results showed water served as a dominant factor controlling the vegetation distributions and NPP. However, temperature became determinant where the biomes changed, impacting the rate of change in vegetation NPP when the climate changed. The results also showed that water would have a positive effect on transect production, and the structure of vegetation had a negative effect under the projected future climate.     

甘肃某含锑金矿浮选尾矿工艺矿物学研究

甘肃某金矿石平均含Au 4.3 g/t,为典型的含锑、砷难处理金矿,现场采用"重选-浮选-浮尾氰化"工艺回收Au,但Au的总回收率仅82%左右,浸渣中Au含量高达1.0~1.2 g/t,损失严重。为查明Au损失原因,提高Au回收率,采用矿物解离度分析仪(MLA),并结合传统的光学显微镜分析,对现场的浮选尾矿(氰化浸出给矿)进行了工艺矿物学研究。结果表明,浮选尾矿含Au 2.8 g/t,但Au赋存状态较为复杂,其中仅29.2%的Au以显微金-明金(粒度≥0.1 mm)形式存在,18.8%和48.2%的Au以超次显微金(粒度0.001 mm)形式赋存于辉锑矿、黄铁矿、毒砂等硫化矿物和石英、白云石、高岭石等硅酸盐矿物中,金嵌布粒度较细和包裹金所占比例较高,难以回收,是Au损失的主要原因。根据工艺矿物学研究结果,对可行的回收方案进行了初步研究。     

西北地区水资源可利用量与承载能力估算

界定了水资源可利用量和径流口径生态需水的概念。对西北地区的径流口径生态需水和水资源可利用量进行估算。西北地区水资源总量为1638 5×108m3,但需净出境水量为411 9×108m3,实有水资源总量为1226 6×108m3,径流口径生态需水量为454 4×108m3,除去保留给生态的生态需水、偏远封闭流域难以利用的水量,人类可以消耗利用的可利用量有742×108m3,其中黄河流域可利用量为187×108m3,西北内流区当地可利用量为555×108m3。建立了水资源承载能力优化计算模型,估算西北地区的水资源承载能力,并建议用水资源承载能力图谱表示水资源承载能力。在人均GDP每10年翻一番、水资源利用效率每年提高7%的条件下,西北地区水资源承载能力2010年为11310万人,2020年为12019万人,2030年为12733万人。     

甘肃阳山金矿带构造岩浆演化与金矿成矿

甘肃阳山金矿带位于西秦岭南部,结合同位素测年资料发现阳山金矿区在侏罗纪早期、白垩纪早期及第三纪早期曾发生3期岩浆活动;稳定同位素分析结果显示,矿石中石英的流体包裹体δD值为-75‰～-56‰,δ¹⁸O_H2O为3.7‰～12.2‰,矿脉中黄铁矿及辉锑矿的δ³⁴S为-2.2‰～-0.7‰,表明阳山金矿成矿热液及成矿物质主要来自于岩浆作用;构造变形分析显示该区在三叠纪曾发生韧性变形,在侏罗纪早期产生韧-脆性变形;侏罗纪晚期以后区内构造转为脆性,早期以逆冲推覆构造为主,晚期主要为脆性伸展活动。结合该区地质构造演化史认为本区的3期岩浆活动与区域伸展作用有关,而与岩浆侵入有关的多期岩浆热液活动是促成阳山金矿床形成的主要因素。     

甘肃黑石山埃达克岩金矿床成矿模式初析

甘肃黑石山埃达克岩属O型埃达克岩,其岩石类型为奥长花岗岩。岩体位于黑石山穹隆南缘,西湾-苏家湾断裂北部上盘。在该埃达克岩体中发育有金矿床,矿床类型为含金石英脉型及蚀变花岗岩型。研究认为该矿床的形成主要经历了3个阶段：Ⅰ．次生洋板片俯冲并发生部分熔融形成埃达克质熔体;Ⅱ．熔体与地幔楔橄榄岩及幔源熔体的相互作用（金属的萃取）使熔体富集成矿元素;Ⅲ．熔体向上侵入成岩,后期构造运动及热液成矿作用使成矿元素活化迁移并最终富集成矿。     

甘肃省玛曲县大水金矿原生金矿石的发现及意义

甘肃玛曲县大水金矿是西秦岭地区规模最大、类型独特的金矿床之一,多年的矿床勘探和开发过程中,在400m以上从未发现过原生金矿体或金矿石,因而对该矿床的成因认识一直存在着争论。本文利用矿山在89线竖井开拓过程中发现的原生金矿石,通过岩矿鉴定、微量元素和稀土元素分析,发现矿区存在英安质凝灰岩,是金矿石寄主岩石之一。原生金矿石具块状、条带状和角砾状构造,凝灰岩矿石或角砾具海底喷流沉积特征。新发现的原生金矿石与花岗闪长斑岩、黑云石英闪长玢岩型金矿石具有不同的微量元素、稀土元素变化趋势和硫同位素值,指示原生金矿石可能经历了喷流和后期岩浆热液改造两个阶段的成矿,这些发现对认识大水金矿床成因和今后找矿方向具有重要指导意义。     

甘肃酒泉盆地早白垩世植物化石及其古气候意义

首次较系统报道了产于甘肃酒泉盆地下白垩统的植物化石,分为两个植物组合。Athrotaxites-Solenites组合产于赤金堡组上段,有Solenites luanpingensis Wang,Pityocladus cf.i waianus(ishi)Chow,Pityocladus sp.,Athrotaxites berryi Bell等,时代大致为早白垩世早期,反映潮湿或半干旱半潮湿气候。Brachyphyllum-Pseudofrenelopsis组合见于中沟组上部,包括Sphenopterissp.,Pseudofrenelopsis dalatzensis(Chowet Tsao)Cao ex Zhou,Cupressinocladus elegans(Chow)Chow,Cupressinocladus sp.,Pagiophyllumyumenense sp.nov.,Pagiophyllumcompressum sp.nov.,Pagiophyllum sp.,Brachyphyllumningshiaense Chow et Tsao,Brachyphyllumobtusum Chow et Tsao,Elatocladus sp.,Podozamites sp.,Carpolithus sp.等12种,时代为Aptian-Albian期,反映干旱型气候。     

Mineralogy of primary carbonate-bearing hypabyssal kimberlite, Lac de Gras, Slave Province, Northwest Territories, Canada

A suite of fresh, Late Cretaceous to Eocene hypabyssal kimberlites from the Lac de Gras field were studied in order to understand better carbonate, silicate and oxide paragenesis. The samples have excellent preservation of textures and primary mineralogy and are archetypal or Group 1 kimberlite. Five kimberlite localities are identified as calcite-bearing based on the presence of high Sr–Ba calcite as phenocrysts, microphenocrysts and in segregations. Three kimberlite localities are identified as dolomite-bearing based on the presence of mixed calcite–dolomite segregations containing oscillatory and banded textures of calcite–dolomite solid solution and dolomite (±magnesite). Sr–Ba calcite are characterized by high X_Ca (>0.95) and are enriched in Sr (4900–11,100 ppm) and Ba (3200–14,200 ppm). The calcite–dolomite and dolomite–magnesite solid solution compositions span the X_Ca range from 0.42 to 0.95, and typically have Sr and Ba contents in the range of 1000–4000 ppm. The carbonate, silicate and oxide mineral compositions suggest that the origin of the calcite-bearing versus dolomite-bearing kimberlites studied is related to subtle differences in parent magma composition, in particular, the CO₂/H₂O ratio. Formation of the carbonates reflects the latter part of a protracted magmatic crystallization sequence, in which Sr–Ba calcite precipitates from an evolved kimberlite melt. Subsequently, calcite–dolomite solid solution and dolomite is precipitated from localized, Mg-rich carbonate fluids at relatively high temperatures (higher than serpentine stability).     

The seismic property of reef flat in the Changxing-Feixianguan Formation, Northwest Sichuan Province, China

The development of a carbonate reservoir is dominated by its primary sedimentary environment. Generally, a good reservoir must be the oolite of a bank or bioclastics of an organic reef in a marginal mesa, which must deposit on the slope of the mesa. Therefore, the analyses of sequence stratigraphy are the key for predicting the presence of carbonate reservoirs. A typical sequence pattern can be seen in the Puguang gas field. As an independent lithological body, the mechanical property of a reef flat is very different from the surrounding rock, causing stress to concentrate. Stress centralization will, in turn, cause a lot of fractures and faults to develop, and ultimately, result in a gas chimney, which is a seismic smear zone beneath or above the reef flat. Known gas fields, such as the puguang gas field, also possess gas chimneys. Sequence stratigraphy patterns in the marginal mesa and gas chimney near the reservoir are very obvious in all known fields in southeast and east Sichuan Province. By analyzing the seismic features of all known gas fields, a model to predict carbonate reservoirs has been set up. Using this prediction model, we have found that there is a typical reef flat of the marginal mesa in the Malubei structure of Tongnanba structural belts whose sequence stratigraphy pattern is very much like that of the Puguang gas field; and in the Cangxi-Jiulongshan structure, there is another reef flat which is symmetrical to the Malubei reef. The Cangxi reef flat possesses the largest platform edge shallow facies domestically found, and has a typical prograding sequence. Its gas chimney is very obvious too. Because the Cangxi reef flat is in the very vicinity of the hydrocarbon kitchen and the depression is much bigger than that of the Puguang gas fields, we predict that there may be a gigascopic gas field in Cangxi County. There may also be a large gas field in the Malubei structure. Translated from Oil & Gas Geology, 2006, 27(3): 332–339 [译自: 石油与天然气地质]     

甘肃河西地区内陆河流域荒漠化的水资源问题

河西地区内陆河流域荒漠化的水资源问题,根本的原因在于水资源短缺而导致的生态环境脆弱和水资源的过度开发利用.如果上、中游地区水资源的利用超过了水资源量的限度,则流到下游的径流量减沙,地下水位下降;而下游地区为了弥补水资源的不足,便大量开采地下水,致使地下水严重超采,从而导致植被退化和荒漠化.在分析上述问题的基础上,以石羊河为例,说明内陆河流域的荒漠化防治要求实行以农业节水为中心,建立节水型社会的流域综合治理,实现水资源、土地资源、经济、社会和生态环境协调和可持续发展.