Study on rain-runoff process in the peripheral mountainous area of the Sichuan Basin

Studies on rain-runoff process in the peripheral mountainous area of the Sichuan Basin, which is regarded as a key ecological shelter, will contribute to flood control and environmental protection for the Upper Yangtze River Basin. In two typical catchments--the Fujiang River Catchment and the Wujiang River Catchment, rainfall simulations have been conducted to study the rain-runoff processes of yellow soil and limestone soil in three types of land use--forestland, farmland and grassland. Results showed that （1） within the same rainfall process, overland flow occurs first on farmland, then on grassland, and finally on forestland; （2） soil surface coverage has a great impact on the occurrence and amount of overland flow. The runoff amount can increase 2-4 times after the coverage is removed; （3） the infiltration before the occurrence of overland flow will decrease because of higher gravel contents of soil, but it takes no effect on infiltration once overland flow becomes stable; （4） the runoff coefficient of the limestone soil forestland is greater than that of the yellow soil forest land, but less than that of the farmland; （5） three empirical infiltration models, including Horton＇ model, Kostiakov＇ model, and modified Kostiakov＇ model, were compared by using the observed results under rainfall simulation. The results showed that the Kostiakov＇ model performed better than both the Horton＇ model and modified Kostiakov model. According to the results of this research, the Kostiakov＇s model can be used to simulate rainfall infiltration when water erosion is modeled in the peripheral mountainous area of the Sichuan Basin.     

Occurrence and evolution of the Xiaotangshan hot spring in Beijing, China

Thermal groundwater occurs in bedrock aquifers consisting of the dolomite of the Wumishan Group of the Jixianin System and the Cambrian carbonate in the Xiaotangshan geothermal field near the northern margin of the North China Plain, China. The hot water in the geothermal field of basin-type discharges partly in the form of the Xiaotangshan hot spring under natural conditions. The hot water has TDS of less than 600 mg/L and is of Na·Ca-HCO₃ type. The geothermal water receives recharge from precipitation in the mountain area with elevation of about 500 m above sea level to the north of the spring. Thermal groundwater flows slowly south and southeast through a deep circulation with a residence time of 224 years estimated with the Ra–Rn method. The Xiaotangshan hot spring dried up in the middle of the 1980s owing to the increasing withdrawal of the hot water in the geothermal field in the past decades. The water level of the geothermal system still falls continually at an annual average rate of about 2 m, although water temperature changes very little, indicating that the recharge of such a geothermal system of basin-type is limited. Over-exploitation has a dramatic impact on the geothermal system, and reduction in exploitation and reinjection are required for the sustainable usage of the hot water.     

区域化探资料在提高农作物产量上的应用成果

1991年,利用冀东地区已有1:20万区域化探资料,进行了在农业中的开发应用研究,在此基础上,选择区内微量营养元素和有益元素缺乏区,开展了增施微量元素Zn、Mn、Mo、B和Co肥料提高水稻、玉米、花生和苹果产量的应用研究。试验结果表明,增施微肥后,水稻、玉米、花生产量提高,平均增产10%以上,亩增收入平均40元以上,苹果增产30%以上,亩增收入大于1000元,增产效果和经济效益是明显的。这项成果如在整个冀东地区推广,其经济效益将是巨大的。     

豫西崤山后河岩体LA-ICP-MS锆石U-Pb定年及其地质意义

与豫西小秦岭和熊耳山地区相类似,崤山北部也出露一系列中酸性小岩体,但与之相关的成矿作用明显较弱,因此长期未获得应有的关注。崤山北部小岩体的形成时代与区域成岩成矿时代之间的匹配关系对其深部构造演化研究及成矿潜力评价具有重要意义,鉴于此,作者对后河岩体进行了LA-ICP-MS锆石U-Pb定年。后河岩体定年样品HH01的岩性为中-细粒黑云母二长花岗岩,30个锆石测点中有27个测点的测定值位于207Pb/235U-206Pb/238U一致线上,相应的206Pb/238U年龄介于124~134 Ma之间,加权平均年龄为128±1Ma(MSWD=1.02),属早白垩世。后河岩体是岩石圈拆沉作用的产物,其形成时代处在东秦岭地区广泛而强烈的成岩成矿作用时限内,且显示了Au、Ag、Cu、Mo、W等元素的异常富集,具有较大的内生金属成矿潜力。     

Petrochemistry,Age and Petrogenesis of the Shexian Pluton in Southern Anhui

The Shexian gneissic granodiorite in southern Anhui trends NE 55° from Shexian in the west to Guitoujian in the east with a length of 22 km and an outcrop area of 32 km. It was considered formerly to be Caledonian on the basis of a biotite K-Ar age of 474 Ma (1982). However, new evidence indicates that it may be Early Jinning in age as shown by: (1) it is found intruding into the Mid-Proterozoic Shangxi Group and is unconformably overlain by the Sinian Xiuning Formation, and (2) a zircon U-Th-Pb age of 928 Ma is obtained for the pluton. The pluton is composed of plagioclase (An=27.37%), K-feldspar(14%), biotite(16%) and quartz(32%). Accessory minerals are ilmenite (150g/T), xenotime (15g/T). garnet(25g/T), monazite(10g/T), zircon (20g/T) and apatite (104g/T). Petrochemical characteristics of the intrusion are:(l) Al-enrichment (A/NKC=1.30); (2) H₂O enrichment (H₂O= 1.74%); and (3) low oxidation index (f ’=0.10). It belongs to the continental crust transformation type as evidenced by: (1) MF and Mg/Y values of biotite are 0.41 and 0.31 respectively; (2) (⁸⁷Sr/⁸⁶Sr)=0.71119; (3) δ Eu=0.52; and (4) A/NKC=130. The Shexian pluton is therefore considered as a product of melting of phyllite at depth in the light of similarities in trace element and REE contents with the phyllite of the Banxi Group. Calculations of REE batch partial melting indicate that it may have resulted from 75% melting of the Banxi phyllite.     

初始主应力方向对钙质砂动力特性影响的试验研究

利用大连理工大学的土工静力-动力液压三轴-扭转动多能剪切仪对相对密度为30 %的钙质砂进行了扭转和竖向循环耦合试验,探讨了初始主应力方向角 对钙质砂动强度和残余应变发展的影响。试验结果表明： 对钙质砂的动强度、残余应变发展的影响非常明显,随着 的增大,钙质砂的动强度显著减小,而残余应变的发展速度则明显加快。     

Generation and Development of Structures and Their Controls on Ore Mineralization in the Lehong Zinc-lead Deposit,Northeastern YunnanEI北大核心CSCD

The Lehong zinc-lead deposit is one of the new-found large Zn-Pb deposits in the Sichuan- Yunnan-Guizhou Zn-Pb poly-metallic mineralization area. The ore-bodies of the Lehong deposit are strictly controlled by structures, and the fault tectonites can be divided into four groups which include morbruk rock, cataclastic rock and tectonic breccia. The mechanical properties of the faults suggest that there are five tectonic systems formed in the Caledonian-early Hercynian, Indosinian-early Yanshanian, mid-Yanshanian, late Yanshanian and Himalayan periods, respectively. The Lehong fault and the Qiaojia-Lianfeng fault are two important ore-controlling structures which might have acted as channel ways of the ore fluids. The ores are hosted in the subordinary fracture zone, joint fracture zone and interlayer fault zones in trailing folds of the Lehong fault and the Baobaoshang syncline and Jinjiagou anticline. Hence, the Lehong deposit is a tectonic -controlled ore deposit. These research do not only lay a foundation for studying deposit genesis and ore-finding direction in the Lehong deposit, but also provides important enlightenments for the ore-finding prognosis of lead-zinc deposits in northwestern Guizhou ore concentration district. © 2018, Science Press. All right reserved.     

Correction of common lead in U-Pb analyses that do not report 204 Pb

During the Early-Middle Proterozoic era, three major lithostratigraphic unit associations, namely Hekou-Dahongshan, Dongchuan, and Kunyang-Huili Groups, were established for the metamorphosed volcanic-sedimentary rocks exposed in the southwestern Yangtze Block (SWYB). The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB, in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions: 1800–1600 Ma, 1600–1300 Ma, 1300–1100 Ma, and 1100–1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages, each coinciding with the above radiometric age set, of the SWYB during the Early-Middle Mesoproterozoic. The SWYB was characterized by an east-westerly trending rift in the Hekou, Dongshan, and Dongchuan areas, and separate basin-forming events during 1800–1600 Ma and 1600–1300 Ma, respectively. In the SWYB, an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300–1100 Ma ago. During 1100–1000 Ma, the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin, collision between the Huili Blocks and Kunyang Blocks, and presence of volcanic arcs in the Tianbaoshan and Fulingpen areas. Accordingly, the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle Mesoproterozoic era.     

Estimates of groundwater discharge to a coastal wetland using multiple techniques: Taylor Slough, Everglades National Park, USA

Quantifying water exchange between a coastal wetland and the underlying groundwater is important for closing water, energy and chemical budgets. The coastal wetlands of the Florida Everglades (USA) are at the forefront of a large hydrologic restoration project, and understanding of groundwater/surface-water interactions is needed to comprehend the effects of the project. Four independent techniques were used to identify water exchange at varying spatial and temporal scales in Taylor Slough, Everglades National Park. The techniques included a water-budget study and measurements of hydraulic head gradients, geochemical tracers, and temperature. During the 18-month study, the four methods converged as to the timing of groundwater discharge, typically between June and September, contemporaneous with the wet season and increasing surface-water levels. These results were unexpected, as groundwater discharge was predicted to be greatest when surface-water levels were low, typically during the dry season. Either a time lag of 1?C5?months in the response of groundwater discharge to low surface-water levels or precipitation-induced groundwater discharge may explain the results. Groundwater discharge was a significant contributor (27?%) to the surface water in Taylor Slough with greater rates of discharge observed towards the coastline in response to seawater intrusion.     

Aluminum in the macrotidal Yalujiang estuary: Partitioning of Al along the estuarine gradients and flux

Water samples were collected from the Yalujiang estuary in both flood periods (August 1992 and August 1994) and dry season (May 1996) and were analyzed for aluminum (Al). Al behaves non-conservatively in the Yalujiang estuary, and a significant loss (70–80%) in dissolved concentration is observed in the upper estuary, in spite of seasonal variation in water discharge and sediment load. About 0.4×10⁶, tons of Al is annually transported from Yalujiang to the estuary, of which the particulate pool clearly dominates. The particulate Al flux through the Yalujiang contributes 35% of the total Al input from Chinese rivers to the Yellow Sea. The data sets from size fractionation and C-18 SPE separation demonstrate that a large fraction of dissolved Al is in colloidal (≈50%) and organically complex (≈60%) forms in the Yalujiang. The observed scavenging from solution to particulate pools in the estuary is most likely through the flocculation of colloidal and organic-complexed Al, which results in a considerable change in dissolved-particulate partitioning, shown by laboratory mixing experiments. Exchange between dissolved and particulate phases is examined by analysis of K_d, the distribution coefficient. The empirical relationship of K_d with chlorinity and suspended matter concentrations was investigated with field observations and model simulations. The model indicated that K_d values of Al are inversely related to the amount of total suspended matter, but K_d-chlorinity plots show different features between dry and flood seasons.