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1.
表碛覆盖型冰川是中国西部较为常见的冰川类型。表碛层存在于大气—冰川冰界面,强烈影响大气圈与冰冻圈之间的热交换。表碛厚度的空间异质性可极大地改变冰川的消融率和物质平衡过程,进而影响冰川径流过程和下游水资源。基于Landsat TM/TIRS数据,运用能量平衡方程反演了贡嘎山地区冰川表碛厚度,研究了贡嘎山地区冰川在1990—2019年间表碛覆盖范围及厚度变化情况,同时对比了东西坡差异。结果表明:① 贡嘎山地区冰川表碛扩张总面积达43.824 km2。其中,海螺沟冰川扩张2.606 km2、磨子沟冰川1.959 km2、燕子沟冰川1.243 km2、大贡巴冰川0.896 km2、小贡巴冰川0.509 km2、南门关沟冰川2.264 km2,年均扩张率分别为3.2%、11.1%、1.5%、0.9%、1.0%和6.5%;② 海螺沟冰川、磨子沟冰川、燕子沟冰川、大贡巴冰川、小贡巴冰川、南门关沟冰川表碛平均增厚分别为5.2 cm、3.1 cm、3.7 cm、6.8 cm、7.3 cm和13.1 cm;③ 西坡冰川表碛覆盖度高,表碛覆盖年均扩张率低,冰川末端退缩量小;东坡冰川表碛覆盖年均扩张率高,但表碛覆盖度总体低于西坡,冰川末端退缩量大。 相似文献
2.
我国东部中低山区第四纪冰川的存在与否一直存在争议,但冰川必然对山体进行冰蚀作用形成冰蚀地貌。为了分析我国东部中低山区的山体地貌是否具有冰蚀特征,该文选取了现代冰川集中发育区-喜马拉雅山脉作为冰蚀地貌的研究对象,通过宏观分析,除了由缩口、三角脊、残弧组成的冰斗系统外,还发现冰蚀作用过程存在避谷、吞脊、切壁、穿梁等特殊习性。分析认为冰蚀过程主要受制于雪线高程、积雪高程与坡向坡角三方面因素的控制。以此为基础,对我国东部的江西庐山、山东蒙山、大兴安岭主峰黄岗梁三个地区的山体地貌进行对比分析,发现这些山区的山体地貌与喜马拉雅山脉的冰蚀地貌具有一致性。文章从冰蚀过程的角度确认了我国东部中低山区存在第四纪冰川的事实。 相似文献
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4.
利用Landsat卫星影像,采用面向对象分类方法提取珠穆朗玛峰自然保护区湖泊信息,分析了湖泊动态及对区域气候变化的响应关系。结果表明:(1)2015年保护区湖泊总面积为489.07 km2,构造湖、河成湖、冰川湖分别占总面积的77.3%、2.6%、20.1%。(2)1975-2015年,保护区内各类湖泊面积变化速率不同,冰川湖最大(1.05 km2·a-1),构造湖次之(-0.85 km2·a-1),河成湖最稳定(0.013 km2·a-1);保护区南坡冰川湖面积变化速率(0.53 km2·a-1)略大于北坡(0.52 km2·a-1)。(3)北坡构造湖、河成湖对区域气候的响应呈阶段性变化规律,1975-2000年珠峰地区气候呈暖湿化趋势,2000年构造湖、河成湖面积达到峰值,两类总计增加22.8 km2;2000-2015年转变为显著的暖干气候,构造湖、河成湖面积均呈减少趋势,总共减少57.16 km2。随着区域气候的变暖,冰川湖总面积不断扩大,近40年间冰川湖面积累计增加43.06 km2。(4)灰色关联度分析显示,年极端低温对构造湖面积变化影响最显著,年均气温对冰川湖起主导作用,年均相对湿度对河成湖影响最大。较其他气候因子而言,降水量对各类湖泊面积变化的影响均最小。 相似文献
5.
Catherine Martin-Jones Christine Lane Maarten Van Daele Thijs Van Der Meeren Christian Wolff Heather Moorhouse Emma Tomlinson Dirk Verschuren 《第四纪科学杂志》2020,35(1-2):245-255
Reconstructions of the timing and frequency of past eruptions are important to assess the propensity for future volcanic activity, yet in volcanic areas such as the East African Rift only piecemeal eruption histories exist. Understanding the volcanic history of scoria-cone fields, where eruptions are often infrequent and deposits strongly weathered, is particularly challenging. Here we reconstruct a history of volcanism from scoria cones situated along the eastern shoulders of the Kenya–Tanzania Rift, using a sequence of tephra (volcanic ash) layers preserved in the ~250-ka sediment record of Lake Chala near Mount Kilimanjaro. Seven visible and two non-visible (crypto-) tephra layers in the Lake Chala sequence are attributed to activity from the Mt Kilimanjaro (northern Tanzania) and the Chyulu Hills (southern Kenya) volcanic fields, on the basis of their glass chemistry, textural characteristics and known eruption chronology. The Lake Chala record of eruptions from scoria cones in the Chyulu Hills volcanic field confirms geological and historical evidence of its recent activity, and provides first-order age estimates for seven previously unknown eruptions. Long and well-resolved sedimentary records such as that of Lake Chala have significant potential for resolving regional eruption chronologies spanning hundreds of thousands of years. 相似文献
6.
1980 - 2015年南迦巴瓦峰地区冰川变化及其对气候变化的响应 总被引:6,自引:5,他引:1
基于地形图和Landsat TM/OLI遥感影像等数据, 利用目视解译和波段比值法提取1980年、 2000年和2015年南迦巴瓦峰地区冰川空间分布数据, 分析研究区近35年冰川变化, 探讨冰川对气候变化的响应。结果表明: 1980 - 2015年, 南迦巴瓦峰地区冰川面积持续减小并呈加速退缩的趋势, 近35年共减少了(75.23±4.67) km2, 占1980年冰川总面积的(25.2±1.6)%, 年平均面积减小率为(0.73±0.05)%。研究区东南坡冰川面积变化速率大于西北坡, 在不同流域、 海拔及朝向上, 冰川变化差异较大。南迦巴瓦峰地区冰川表碛十分发育, 表碛覆盖冰川面积变化率小于裸露冰川, 表碛覆盖对冰川消融具有抑制作用。南迦巴瓦峰地区在气温显著升高的背景下, 虽然降水量有所增加, 但冰川对气温更加敏感, 因气温升高引起冰川消融所带来的物质损失超过降水增加对冰川的补给, 导致南迦巴瓦峰地区冰川普遍萎缩。 相似文献
7.
利用太白山北麓2011年12月-2013年7月共39次降水样品数据资料,定量分析了该区域降水化学的特征和时间变化规律.结果表明:太白山北麓地区降水中,除常量离子Na+、NH4+ K+、Mg2、Ca2+、F-、C1-、SO42-、NO3-外,CO32-、HCO3-、PO43-及低分子有机酸也占有相当比例.研究区降水常量离子浓度的顺序依次为:NH4+ >SO42->Ca2+ >NO3->Na+ >Cl->Mg2+ >K+ >F-,离子总浓度表现出明显的季节变化:夏季(轻度污染)<秋季(中等污染)<春季(严重污染)<冬季(极重污染).利用因子分析法得出太白山北麓地区降水组分主要有三种来源;Na+、C1-、Mg2+、Ca2+主要来自地壳源,SO42-、NO3-、NH4+主要来自人为源,K+和F-主要由海盐源和人为源共同贡献.根据Hysplit后向气流轨迹分析,得出不同路径气团降水离子组分不同:受地形等因素影响,北方路径的气团比南方路径气团离子总浓度较高;受土壤类型影响,西北方向气团降水Na+、Mg2+、Ca2+浓度较高;受人为活动影响,东北方向SO42-、NO3-、NH4+浓度较高. 相似文献
8.
In 2006, the United States Geological Survey (USGS) completed a detailed analysis and interpretation of available 2-D and 3-D seismic data, along with seismic modeling and correlation with specially processed downhole well log data for identifying potential gas hydrate accumulations on the North Slope of Alaska. A methodology was developed for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area. The study revealed a total of 14 gas hydrate prospects in this area.In order to validate the gas hydrate prospecting protocol of the USGS and to acquire critical reservoir data needed to develop a longer-term production testing program, a stratigraphic test well was drilled at the Mount Elbert prospect in the Milne Point area in early 2007. The drilling confirmed the presence of two prominent gas-hydrate-bearing units in the Mount Elbert prospect, and high quality well logs and core data were acquired. The post-drill results indicate pre-drill predictions of the reservoir thickness and the gas-hydrate saturations based on seismic and existing well data were 90% accurate for the upper unit (hydrate unit D) and 70% accurate for the lower unit (hydrate unit C), confirming the validity of the USGS approach to gas hydrate prospecting. The Mount Elbert prospect is the first gas hydrate accumulation on the North Slope of Alaska identified primarily on the basis of seismic attribute analysis and specially processed downhole log data. Post-drill well log data enabled a better constraint of the elastic model and the development of an improved approach to the gas hydrate prospecting using seismic attributes. 相似文献
9.
山东蒙山八字峪(亦有人称为瑶池)砾石堆积堤不连续对称分布于出山沟口,沿流向延伸,具有弧形或舌状沉积的典型特征。2020年10月在蒙山八字峪砾石堆积堤测量了56块砾石组构,并在叠置砾石隙间采集到4个树干~(14)C测年样品。研究结果如下:(1)八字峪堆积垄岗砾石组构、沉积构造、地貌组合等标志,均指向其为山洪泥石流堆积物;(2)缺少扇形地、表泥层与底泥层,具有砂砾透镜体的砾石层,揭示八字峪砾石堤为暴发频率极低、发展周期较长的泥石流堆积;(3)根据已有测年结果和乔木定居期,八字峪砾石堤在距今50年前曾发生山洪灾害,这与文献记载具有一致性;(4)八字峪砾石堤成因属于暴雨直接类特大型历史泥石流,可能是一次性、短历时快速地貌灾害过程,且被后期洪流有所改造;(5)八字峪砾石堤形成原因与冰川作用无关,也不是"典型的石河"。已报道的蒙山"冰川遗迹",不仅缺少可靠的三要素地貌组合证据,而且缺少年代学和沉积学依据。总之,本文从证据链上进一步增强了蒙山山麓碎屑堆积为山洪泥石流成因判别的确定性。 相似文献
10.
Precipitation runoff is a critical hillslope hydrological process for downslope streamflow and piedmont/floodplain recharge. Shimen hillslope micro‐catchment is strategically located in the central foothill region of Taihang Mountains, where runoff is crucial for water availability in the piedmont corridors and floodplains of north China. This study analyzes precipitation‐runoff processes in the Shimen hillslope micro‐catchment for 2006–2008 using locally designed runoff collection systems. The study shows that slope length is a critical factor, next only to precipitation, in terms of runoff yield. Regression analysis also shows that runoff is related positively to precipitation, and negatively to slope length. Soil mantle in the study area is generally thin and is therefore not as critical a runoff factor as slope length. The study shows a significant difference between overland and subsurface runoff. However, that between the 0–10 and 10–20 cm subsurfaces is insignificant. Runoff hardly occurs under light rains (<10 mm), but is clearly noticeable under moderate‐to‐rainstorm events. In the hillslope catchment, vertical infiltration (accounting for 42–84% of the precipitation) dominates runoff processes in subsurface soils and weathered granite gneiss bedrock. A weak lateral flow (at even the soil/bedrock interface) and the generally small runoff suggest strong infiltration loss via deep percolation. This is critical for groundwater recharge in the downslope piedmont corridors and floodplains. This may enhance water availability, ease water shortage, avert further environmental degradation, and reduce the risk of drought/flood in the event of extreme weather conditions in the catchment and the wider north China Plain. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献