Since 1980’s Chinese geologists have organized several scientific expeditions with foreign colleagues to enter the Canyon to study its geology and geography.1\ Major petrologic units\;There are three major petrologic...Since 1980’s Chinese geologists have organized several scientific expeditions with foreign colleagues to enter the Canyon to study its geology and geography.1\ Major petrologic units\;There are three major petrologic units in this region: (1)Namche barwa formation(Pt nj ). It is situated in the center of great bend area ,representing the lower part of Indian plate wedged into Eurasia plate, which is composed of plagioclase gneiss, amphibole\|containing high\|pressure granulite lenses. (2)Gandise formation(Pt gd ).It is exposed in the outside of Namche barwa edge(Pt nj ), and is considered to be the lower part of Eurasia plate which is composed of plagioclase\|gneiss, amphibolite, marble, quartzite, etc., and were intruded by large granite batholiths (γ 2 5 to γ 6). (3)Great bend formation(Mz). It stretches along Yarlung Zangbo river and is constrained between Pt nj and Pt gd . It is composed of metamorphic basic igneous rocks , ultramafic rocks and quartzite. The whole rock assemblage is characterized by ophiolite suite. Nice ophiolitic mélange exposures exist in Pangxin, Jiaresa and between Pailong and Zhaqu.2\ Basic rock assemblage\;The present ophiolitic components are mostly metamorphic rocks after structural movements and metamorphism for long period. (1) Meta\|intermediate rocks. Amphibolite is a dominant component of ophiolitic mélange in this region . Chemical analysis and protolith recognition shows that amphibolite originated from basalt, diabase and gabbro. (2) Ultramafic rocks. This kind of rocks distributes along the northeast edge of the wedge from Pangxin to Jiaresa. Original pyroxene\|olivinite and serpentine exposures have been found . Electronic\|probe and bulk\|rock analysis suggest that original olivinite is strongly MgO\|enriched and can be named magnesian olivinite. (3) Quartzite. It is exposed along the northeast and southeast margin of the wedge forming steep cliffs and high peaks . In some places it consists of pure fine\|grained quartz and may contain muscovite, biotite, plagioclase or epidote grains in different amount, which suggest that quartzite in this area was formed in small sea basin and not deep oceanic environment as traditionally considered for standard ophiolite suite. (4) Marble blocks. Pure white marble blocks have been found near the village of Bayu and Daduka which were surrounded by amphibolite , quartzite (Mz) or plagioclase\|gneiss(Pt nj ).展开更多
为了解雅鲁藏布大峡谷区域植物的生态适应性及N、P养分利用特征,该研究在墨脱不同森林植被区选取6个采样点,对每个采样点优势植物进行了植物叶片C、N、P化学计量特征分析。结果表明,研究区植物叶片碳含量均值为452 g kg^(-1),在不同采...为了解雅鲁藏布大峡谷区域植物的生态适应性及N、P养分利用特征,该研究在墨脱不同森林植被区选取6个采样点,对每个采样点优势植物进行了植物叶片C、N、P化学计量特征分析。结果表明,研究区植物叶片碳含量均值为452 g kg^(-1),在不同采样点之间差异未达到显著水平,其余指标在部分采样点之间则存在一定的差异;从生活型看,研究区木本植物叶片碳含量要高于草本植物,氮含量差异不显著,磷含量则低于草本植物;在不同采样点之间木本植物叶片碳氮磷含量差异不显著,木本植物碳氮差异也不显著,但草本植物部分采样点之间磷差异达到显著水平;相关性分析显示,植物叶片C与N、C与P相关性均不显著,但N、P相关性达到极显著水平;墨脱常绿阔叶林区植物叶片C含量略低于我国南方其它常绿阔叶林区植物叶片碳含量,氮含量略高于其他区域,但P含量显著高于其他区域的植物叶片P含量,因此C/N,C/P及N/P均较低,N/P的均值为11.4。本研究结果支持植物叶片氮磷在不同生境中均存在明显正相关关系,结合生长速率假说,墨脱常绿阔叶林区的植物生长速率可能远高于我国其他常绿阔叶林区,因此研究区森林生态系统的碳汇以及面对全球N沉降背景下的响应值得进一步研究。展开更多
藏东南地区的雅鲁藏布大峡谷地区(以下简称大峡谷地区)是印度洋暖湿气流输送至青藏高原的重要通道,在高原水分与能量循环过程中具有重要地位。为了揭示不同水汽输送对陆-气间水热交换通量的影响,本文利用欧洲中期天气预报中心第五代再...藏东南地区的雅鲁藏布大峡谷地区(以下简称大峡谷地区)是印度洋暖湿气流输送至青藏高原的重要通道,在高原水分与能量循环过程中具有重要地位。为了揭示不同水汽输送对陆-气间水热交换通量的影响,本文利用欧洲中期天气预报中心第五代再分析数据产品,根据大气中总水汽含量和水汽水平输送通量将大峡谷地区2013年5月20日至7月9日的水汽强度划分为强/弱/极弱三种级别。并利用第五代公用陆面模式(Community Land Model version 5.0,CLM5.0)模拟了水汽输送对大峡谷-大气间水热交换的影响。研究表明:大峡谷地区的南(东)边界为水汽主要的输入(输出)边界,大峡谷南侧河谷存在水汽强输送带。CLM5.0模拟的大峡谷-大气间水热交换通量与实际相比误差较大,通过优选热力学粗糙度参数化方案和土壤属性替代数据集,提高了CLM5.0模拟大峡谷-大气间水热交换通量的精度。其中Zeng and Dickinson(1998)的方案(以下简称Z98方案)效果最优,较CLM5.0默认参数化方案下模拟的小麦站和草地站近地面感热通量均方根误差分别下降18.2%和10.9%。区域模拟结果显示:大峡谷地区近地面潜热通量区域模拟总体分布为东南高而西北低,近地面感热通量则相反,随水汽水平输送强度的减弱,潜热通量大值区向西北延伸面增大,而感热通量大值区则向东南延伸面增大。冰雪覆盖的高海拔地区近地面感热通量维持低值,而潜热通量则相反。整个试验阶段,大峡谷地区降水时长达59%,不同水汽输送条件下近地面有效能量主要以潜热的方式向大气输送,其中在强水汽水平输送条件下的水汽强输送带的近地面感热输送最弱,Z98方案下的感热通量日均值仅为-1.80 W·m^(-2),潜热通量则大于70.0 W·m^(-2)。对于大峡谷地区,当水汽维持高值范围时,近地面净辐射降低,但近地面净辐射主要被潜热消化,水汽保温大气的效应使得地-气温差降低,近地面感热输送抑制显著。本研究结果对认识雅鲁藏布大峡谷地区陆面过程及其对水汽水平输送的响应有一定的参考价值。展开更多
文摘Since 1980’s Chinese geologists have organized several scientific expeditions with foreign colleagues to enter the Canyon to study its geology and geography.1\ Major petrologic units\;There are three major petrologic units in this region: (1)Namche barwa formation(Pt nj ). It is situated in the center of great bend area ,representing the lower part of Indian plate wedged into Eurasia plate, which is composed of plagioclase gneiss, amphibole\|containing high\|pressure granulite lenses. (2)Gandise formation(Pt gd ).It is exposed in the outside of Namche barwa edge(Pt nj ), and is considered to be the lower part of Eurasia plate which is composed of plagioclase\|gneiss, amphibolite, marble, quartzite, etc., and were intruded by large granite batholiths (γ 2 5 to γ 6). (3)Great bend formation(Mz). It stretches along Yarlung Zangbo river and is constrained between Pt nj and Pt gd . It is composed of metamorphic basic igneous rocks , ultramafic rocks and quartzite. The whole rock assemblage is characterized by ophiolite suite. Nice ophiolitic mélange exposures exist in Pangxin, Jiaresa and between Pailong and Zhaqu.2\ Basic rock assemblage\;The present ophiolitic components are mostly metamorphic rocks after structural movements and metamorphism for long period. (1) Meta\|intermediate rocks. Amphibolite is a dominant component of ophiolitic mélange in this region . Chemical analysis and protolith recognition shows that amphibolite originated from basalt, diabase and gabbro. (2) Ultramafic rocks. This kind of rocks distributes along the northeast edge of the wedge from Pangxin to Jiaresa. Original pyroxene\|olivinite and serpentine exposures have been found . Electronic\|probe and bulk\|rock analysis suggest that original olivinite is strongly MgO\|enriched and can be named magnesian olivinite. (3) Quartzite. It is exposed along the northeast and southeast margin of the wedge forming steep cliffs and high peaks . In some places it consists of pure fine\|grained quartz and may contain muscovite, biotite, plagioclase or epidote grains in different amount, which suggest that quartzite in this area was formed in small sea basin and not deep oceanic environment as traditionally considered for standard ophiolite suite. (4) Marble blocks. Pure white marble blocks have been found near the village of Bayu and Daduka which were surrounded by amphibolite , quartzite (Mz) or plagioclase\|gneiss(Pt nj ).
文摘为了解雅鲁藏布大峡谷区域植物的生态适应性及N、P养分利用特征,该研究在墨脱不同森林植被区选取6个采样点,对每个采样点优势植物进行了植物叶片C、N、P化学计量特征分析。结果表明,研究区植物叶片碳含量均值为452 g kg^(-1),在不同采样点之间差异未达到显著水平,其余指标在部分采样点之间则存在一定的差异;从生活型看,研究区木本植物叶片碳含量要高于草本植物,氮含量差异不显著,磷含量则低于草本植物;在不同采样点之间木本植物叶片碳氮磷含量差异不显著,木本植物碳氮差异也不显著,但草本植物部分采样点之间磷差异达到显著水平;相关性分析显示,植物叶片C与N、C与P相关性均不显著,但N、P相关性达到极显著水平;墨脱常绿阔叶林区植物叶片C含量略低于我国南方其它常绿阔叶林区植物叶片碳含量,氮含量略高于其他区域,但P含量显著高于其他区域的植物叶片P含量,因此C/N,C/P及N/P均较低,N/P的均值为11.4。本研究结果支持植物叶片氮磷在不同生境中均存在明显正相关关系,结合生长速率假说,墨脱常绿阔叶林区的植物生长速率可能远高于我国其他常绿阔叶林区,因此研究区森林生态系统的碳汇以及面对全球N沉降背景下的响应值得进一步研究。
文摘藏东南地区的雅鲁藏布大峡谷地区(以下简称大峡谷地区)是印度洋暖湿气流输送至青藏高原的重要通道,在高原水分与能量循环过程中具有重要地位。为了揭示不同水汽输送对陆-气间水热交换通量的影响,本文利用欧洲中期天气预报中心第五代再分析数据产品,根据大气中总水汽含量和水汽水平输送通量将大峡谷地区2013年5月20日至7月9日的水汽强度划分为强/弱/极弱三种级别。并利用第五代公用陆面模式(Community Land Model version 5.0,CLM5.0)模拟了水汽输送对大峡谷-大气间水热交换的影响。研究表明:大峡谷地区的南(东)边界为水汽主要的输入(输出)边界,大峡谷南侧河谷存在水汽强输送带。CLM5.0模拟的大峡谷-大气间水热交换通量与实际相比误差较大,通过优选热力学粗糙度参数化方案和土壤属性替代数据集,提高了CLM5.0模拟大峡谷-大气间水热交换通量的精度。其中Zeng and Dickinson(1998)的方案(以下简称Z98方案)效果最优,较CLM5.0默认参数化方案下模拟的小麦站和草地站近地面感热通量均方根误差分别下降18.2%和10.9%。区域模拟结果显示:大峡谷地区近地面潜热通量区域模拟总体分布为东南高而西北低,近地面感热通量则相反,随水汽水平输送强度的减弱,潜热通量大值区向西北延伸面增大,而感热通量大值区则向东南延伸面增大。冰雪覆盖的高海拔地区近地面感热通量维持低值,而潜热通量则相反。整个试验阶段,大峡谷地区降水时长达59%,不同水汽输送条件下近地面有效能量主要以潜热的方式向大气输送,其中在强水汽水平输送条件下的水汽强输送带的近地面感热输送最弱,Z98方案下的感热通量日均值仅为-1.80 W·m^(-2),潜热通量则大于70.0 W·m^(-2)。对于大峡谷地区,当水汽维持高值范围时,近地面净辐射降低,但近地面净辐射主要被潜热消化,水汽保温大气的效应使得地-气温差降低,近地面感热输送抑制显著。本研究结果对认识雅鲁藏布大峡谷地区陆面过程及其对水汽水平输送的响应有一定的参考价值。
