Paleohydrology and paleochemistry of Lake Manitoba,Canada: the isotope and ostracode records

Lake Manitoba, the largest lake in the Prairie region of North America, contains a fine-grained sequence of late Pleistocene and Holocene sediment that documents a complex postglacial history. This record indicates that differential isostatic rebound and changing climate have interacted with varying drainage basin size and hydrologic budget to create significant variations in lake level and limnological conditions. During the initial depositional period in the basin, the Lake Agassiz phase (12–9 ka), ¹⁸O of ostracodes ranged from –16 to –5 (PDB), implying the lake was variously dominated by cold, dilute glacial meltwater and warm to cold, slightly saline water.Candona subtriangulata, which prefers cold, dilute water, dominates the most negative ¹⁸O intervals, when the basin was part of proglacial Lake Agassiz. At times during this early phase, the ¹⁸O of the lake abruptly shifted to higher values; euryhaline taxa such asC. rawsoni orLimnocythere ceriotuberosa, and halobiont taxa such asL. staplini orL. sappaensis are dominant in these intervals. This positive covariance of isotope and ostracode records implies that the lake level episodically fell, isolating the Lake Manitoba basin from the main glacial lake.¹⁸O values from inorganic endogenic Mg-calcite in the post-Agassiz phase of Lake Manitoba trend from –4 at 8 ka to –11 at 4.5 ka. We interpret that this trend indicates a gradually increasing influence of isotopically low (–20 SMOW) Paleozoic groundwater inflow, although periods of increased evaporation during this time may account for zones of less negative isotopic values. The ¹⁸O of this inorganic calcite abruptly shifts to higher values (–6) after 4.5 ka due to the combined effects of increased evaporative enrichment in a closed basin lake and the increased contribution of isotopically high surface water inflow on the hydrologic budget. After 2 ka, the ¹⁸O of the Mg-calcite fluctuates between –13 and –7, implying short-term variability in the lake's hydrologic budget, with values indicating the lake varied from outflow-dominated to evaporation-dominated. The ¹³C values of Mg-calcite remain nearly constant from 8 to 4.5 ka and then trend to higher values upward in the section. This pattern suggests primary productivity in the lake was initially constant but gradually increased after 4.5 ka.This is the sixth in a series of papers published in this issue on the paleolimnology of arid regions. These papers were presented at the Sixth International Palaeolimnology Symposium held 19–21 April, 1993 at the Australian National University, Canberra, Australia. Dr A. R. Chivas served as guest editor for these papers.     

江西省安福地区地热水化学特征研究

为研究江西安福地区水文地球化学特征及控制因素, 本文采集了15组样品, 采用水化学、同位素分析等方法进行研究。结果表明: 研究区地热水以Na-HCO3型水为主, 地下水以HCO3-Na·Ca型为主, 地表水由西南向东北从HCO3-Na·Ca向HCO3-Ca型水演化。水化学组分演化过程主要受岩石风化作用控制, 地层封闭性较差, 水中的Na+、HCO– 3、Sr2+来源于硅酸岩风化溶解。由稳定同位素特征可知, 研究区地热水补给来源为大气降水。研究区热储温度为49.8~101.4 ℃, 地热水循环深度为1 502.6~1 513.6 m。热水在沿断裂带上升过程中与浅层冷水发生混合, 其混合比例为76.1%~87.5%。研究成果为安福地区水循环演化提供依据, 有利于地热资源的合理开采与保护。     

基于泛珠三角的广东工业旅游探讨

基于建立泛珠三角的研究背景，通过对广州发展工业旅游的条件的分析得出结论，认为由于地缘关系和历史原因，在泛珠三角的成员中，广东最早接受香港地区的经济辐射，港澳台投资者在广东大量投资建厂，工业优势也日渐凸显，这种得天独厚的优势，为广东发展工业旅游奠定了坚实的基础。并通过对广东工业旅游示范点和其他适合发展工业旅游的企业进行调查分析和实证研究，总结了广东发展工业旅游的主要客源类型，并对广东工业旅游的发展提出了几点发展思路。工业与旅游相结合，两者完全可以达到双赢，并可以得到一定的社会效益，也是结论性认识。     

西北旅游落后现状的突破及列车旅游的新思路--兼论"西部之星"旅游列车的产品设计

近几年，西北地区的旅游业虽然取得了很大的成绩，但其发展相对于东部地区却显得落后，其主要原因之一就是西北地区的旅游资源过于分散，景点间距过大，由此导致游览行程过长，游览内容单薄，这在客观上影响了游客的选择。而与此同时，在国外，列车旅游早已作为各国旅游业的重要旅游产品为世人所熟知。文章从分析我国西北旅游业发展的现状入手，针对景点分散这一制约我国西部旅游业发展的客观不利因素，肯定了开发旅游列车产品的思路。作者以西北地区为例，结合目前我国旅游专列发展现状，提出开通“西部之星”旅游列车的构想，并进行了初步的设计。     

Geochemistry of recent hydrothermal systems of Mendeleev Volcano （Kuril Islands） and surrounding waters

On the Kuril Islands there are 85 volcanoes, 39 of which are active. Hot springs and mud pots are wide spread in this area and have significant inputs on the chemical composition of the surrounding surface waters and environment. We present results of trace elements as well as data on H, O, S, and He isotope ratios for hydrothermal systems of the Mendeleev Volcano （Kunashir Island） and surrounding surface waters. Water and gas samples were taken from springs and holes as well as creeks and the Lesnaya River. Among the thermal water types, three main groups can be distinguished. The first group includes the waters, in which SO4^- ion predominant. The water temperature on the surface reaches 97℃, and TDS varies from a few g/L to 7 g/L. These waters are acid to superacid with pH values ranging 0.6 to 2.3. The second group is sodium-chloride waters. A maximum TDS is 14.2 g/L. The waters are neutral or alkaline; pH varies from 6.9 to 8.2. The third group is the sodium-chloride-sulfate-bicarbonate water. The Stolbovskie springs, located in the periphery of the Mendeleev Volcano are representative of this type. The pH of these waters is close to neutral. TDS is 1.9 g/L. They are rather the derivatives of sodium-chloride waters arisen from dilution of them by subsurface waters. The Kuslyi Creek and Lesnaya River are located near the Mendeleev Volcano. The most acid springs discharge into the Kislyi Creek as a result pH of this creek being 2.5, and contents of most elements rather high. For example, the contents of dissolved solids of Si, Fe, Al, Mn, Zn, in waters of the Kislaya Creek are 22.1, 8.1, 6.2, 1.29, and 0.28 mg/L, and correspondently. The water of the Lesnaya River, （Before the Kislyi Creek, pH is about 8 with TDS 102 mg/L, but after the Kuslyi Creek, pH decreases and the concentrations of chemical elements increase. Debit of the Kislayi Creek in summer season is about 370 L/sec. It means that every day only this small creek inputs in the Lesnay River about 706 kg of Si;     

广东河源盆地蛋化石

河源盆地沉积了白垩系-古近系，笔者将这套地层划分为3个岩石地层单位，新建仙塘组和东源组，沿用格岭组。在河源除发现恐龙骨骼、恐龙脚印、龟鳖化石外，于白垩系东源组中还产有大量蛋化石。该组蛋化石的分布，下部以圆形蛋为主，中-上部多见长形蛋。报道了三王坝村副圆形蛋(新种)Paraspheroolithus sanwangbacunensis Fang sp．nov．、风光村树枝蛋(新种)Dendroolithus fengguangcunensis Fang sp．nov．和瑶屯巨形蛋Macroolithus yaotunensis、长形长形蛋Elongatoolithus elongates。     

广东省特色农作物标准波谱数据库框架设计与示范应用

本研究着眼于广东省典型特色农作物的波谱，建立了波谱数据库，该库分为知识库、遥感实测波谱库、模型库、波谱分析和 荔枝园示范5大部分。 在波谱分析模块设计上提供了波谱数据查询、分析等功能，通过对荔枝园种植面积应用示范，给用户提供了极 大方便。     

西昆仑地区塔木MVT型铅锌矿床成矿作用和成矿物质来源探讨

MVT型铅锌矿是西昆仑地区重要的铅锌矿床类型之一.为了探明西昆仑地区该类型矿床的成矿作用过程和成矿物质来源,本文以塔木矿床为例,在野外调研基础上,进行了光片鉴定、铅硫同位素、稀士元素和成矿元素研究,得到矿石中方铅矿的δ34SCDT为-5.04‰～+3.67‰,反映出油田卤水与深层卤水的混合特征;由铅同位素分析结果计算出表面年龄为461～481 Ma(早于泥盆纪438～410 Ma);由稀土元素分析数据得出岩(矿)石/球粒陨石标准化分配模式图表明,成矿物质主要来自地层.因而判定主要成矿物质可能来源于前泥盆系地层.喜马拉雅期逆冲推覆构造作用所引发的大规模热卤水运移、循环过程,导致矿质的进一步富集、沉淀.     

云南腾冲地块北部空树河组一个菱铁矿结核中的C、O同位素变化特征

空树河组是滇西腾冲地块北部的石碳－二叠纪冈瓦纳相沉积。菱铁矿结核见于该组顶部的黑色泥岩中。将一个结核通过中心切开，在切面上由中心向边缘用牙钻等间隔提取10个样品。同位素测试结果显示，δ^13C自中心向边缘逐渐由－8．09％减为－16．12％，最外一个样例外（－15．39‰），而δ^18O自中心向边缘逐渐由－10．64‰增加为0‰左右。δ^13C的变化情况表明，菱铁矿结核可能形成于硫酸盐还原带。在解释δ^18o的变化情况时，推测在结核开始生长时可能有δ^18O亏损的大气降水掺入，随着埋藏深度的逐渐加大，孔隙水的O同位素逐渐趋近正常海水的值（0‰）。     

Sm-Nd ISOTOPIC AGE OF LAMPROPHYRES IN THE GEZHEN GOLD-BEARING SHEAR ZONE ON HAINAN ISLAND AND ITS GEOLOGICAL IMPLICATIONS

Sm-Nd isotopic compositions of eight lamprophyre samples, which come from the Gezhen gold-bearing shear zone on western Hainan Island, are measured. The Sm-Nd isochron age is 495.98±13.14 Ma, (143Nd/144Nd) 0=0.512094, εNd(t) ranges from +1.80 to +2.00 and TDM from 982 Ma to 1196 Ma (average: 1060 Ma). The authors point out that the whole-rock Sm-Nd isochron age (495.98 ± 13.14 Ma) really represents the petrogenetic age of lamprophyre and the time of magmatism during subsequent subduction.