新疆科克苏湿地植被生物量时空分布特征及与水文连通的关系

区域植被生物量及其与水文连通之间的定量关系对于湿地保护和管理具有重要意义。基于多期Landsat-8遥感影像和野外实地调查数据,提取了新疆科克苏湿地生长季不同月份的湿地水体斑块,反演并分析了湿地植被地上生物量及时空分布特征,量化了水文连通与科克苏湿地植被地上生物量和植被碳库的关系。结果表明:6月新疆科克苏湿地水体斑块面积最大,占保护区面积的63.12%,之后湿地水体斑块面积逐渐减少,8月水体斑块面积仅占保护区面积的6.27%,水体斑块分布具有明显的季节性特征。科克苏湿地植被生物量呈现聚集分布的空间分布模式,额尔齐斯河及克兰河河道两侧以及支流两侧湿地为高生物量区域,北部阿热勒齐及阔克苏村和东南部萨尔胡松乡为低生物量区域。7月地上生物量达到生长季最高值,该时段科克苏湿地的植被总生物量为1.09×10^(9)kg,最大总生物量为4832 g/m^(2),地上生物量较高区域分布在西部的阿克铁热克村及东部的巴勒喀木斯村。水文连通与植被地上生物量及植被碳库呈现抛物线关系,水文连通度为0.6左右时,植被地上生物量及植被总碳库最大,植被总碳库达到4.5×10^(11)kg C。研究揭示了科克苏湿地植被生物量的时空分布特征,建立了科克苏湿地水文连通度与植被地上生物量及植被碳库的量化关系,明确了适宜的水文连通度对植被生物量积累存在促进作用,可为湿地水文连通调控和植被碳储存功能提升提供有效参考。

Phase Equilibrium Modeling of Retrograded Eclogite at the Kekesu Valley, Eastern Segment of SW Tianshan Orogen and Tectonic Implications

In this study, we report newly found strongly retrograded eclogite blocks in the Kekesu Valley, eastern segment of southwestern Tianshan, northwestern China. Based on detailed petrographi- cal studies and mineral chemistry analyses, we constrain P-T evolution of two representative samples via phase equilibrium modeling method using THERMOCALC software. The peak stage is evidenced by the primary inclusions of omphacite＋glaucophane＋lawsonite （inferred）＋chlorite＋white mica in garnet. Using grossular and pyrope isopleth thermobarometry in garnet, the P peak conditions for this stage were con- strained to be -23 kbar, 480-500℃ and the T peak conditions were constrained to be 19-20 kbar, 500-520℃. Subsequent exhumation led to the transformation of lawsonite to epidote. Using Si-in- phengite barometry, the P was constrained to be 16-20 kbar at T of 500-520 ℃ for this stage. Further retrograde stage was evidenced by the mineral assemblages of glaucophane＋garnet＋epidote＋paragonite＋ chlorite＋white mica＋quartz. Later stage retrogression is evidenced by glaucophane＋epidote＋chlorite＋ quartz＋white mica＋albite＋aetinolite with P of 5-9 kbar when T〈490 ~C, indicating the eclogite may have been exhumed to the middle crust level and overprinted by blueschist-greenschist facies metamorphism. The results show that eclogite at the eastern segment of SW Tianshan shares similar P-T path to the HP rocks from the western segment, implying a similar P-T evolution for these rocks.

Petrology and phase equilibrium of newly found eclogites from Kekesu Valley in eastern part of southwest Tianshan HP-UHP metamorphic belt,China,and its tectonic significance

Eclogites and omphacite-bearing blueschists have been newly found in the eastern segment of the southwest Tianshan orogenic belt, Xinjiang, northwest China. After detailed petrological study, three samples including one fresh eclogite TK003, one blueschist sample TK026-8 and one retrograded eclogite TK027, were selected for phase equilibrium modeling under NC（K）MnFMASHO （N20-CaO-K20-MnO-FeO-MgO-A1203-SiO2-H：O-O） system, by thermocalc 3.33 software. Composition analyses of garnets in these three samples show typical growth zoning with Xpy and Xgrs increasing, Xspss decreasing from core to rim. Pseudosection modeling of the garnet zonation reflects that the eclogites and blueschist experienced a similar P-T evo- lution trajectory, with a near iso-baric heating in the early stage, and reached eclogite facies metamorphic field with peak P-T regime of 480-515~C, 2.00-2.30 GPa. Subsequently the rocks experienced an early iso-thermal decompression retrograde stage with P-T conditions of 515-519~C, 1.78-1.93 GPa. Variations of mineralogy and modes of these rocks are probably due to different retrograde paths as a consequence of different bulk-rock composition, as well as a variation in fluid activity during exhumation. P-T calculation and a peak geothermal gradient of 6-7~C/km indicate HP rocks in the Kekesu Valley experienced cold subducted eclogite facies metamorphism. Thus a huge oceanic subduction eclogite facies metamorphic belt in southwest Tianshan has been recognized, extending from the Kekesu Valley in the east to the Muzhaerte Valley in the west for nearly 200 kin. However, UHP evidence has not been found in the Kekesu terrane, perhaps because the slab in east part of southwest Tianshan did not subduct into such a great depth.

中天山科克苏河地区隆升剥蚀历史——来自(U-Th)/He年龄的制约

天山是中亚造山带重要组成部分,其中-新生代构造热演化及隆升剥露史研究是认识中亚造山带构造变形过程与机制的关键.本文应用磷灰石(U-Th)/He技术重建中天山南缘科克苏河地区中-新生代构造热演化及隆升剥蚀过程.磷灰石(U-Th)/He数据综合解释及热演化史模拟表明该地区至少存在晚白垩世、早中新世、晚中新世3期快速隆升剥蚀事件,起始时间分别为~90Ma、~13Ma及~5Ma,且这3期隆升剥蚀事件在整个天山地区具有广泛的可对比性.相对于磷灰石裂变径迹,磷灰石(U-Th)/He年龄记录了中天山南缘地质演化史中更新和更近的热信息,即中天山在晚中新世(~5 Ma)快速隆升剥蚀,其剥蚀速率为~0.47mm·a^(-1),剥蚀厚度为~2300m.总体上,中天山科克苏地区隆升剥蚀起始时间从天山造山带向昭苏盆地(由南向北)逐渐变老,表明了中天山南缘隆升剥蚀存在不均一性,并发生了多期揭顶剥蚀事件.

基于NDVI科克苏湿地蒸散量时空变化特征分析

【目的】分析科克苏湿地蒸散量时空变化特征。【方法】采用ArcGIS10.2和ENVI4.5/ID软件平台,利用涡度相关系统实测的ET时间序列数据和MODIS MOD13Q1产品的NDVI遥感数据集估算的ET空间数据,分析2018和2019年科克苏湿地蒸散量的时空变化特征。【结果】(1)科克苏湿地蒸散量年内时序呈单峰型分布,变化特征明显,2018和2019年7月蒸散量值最高分别为313.31和302.54 mm,占全区蒸散量的27.72%和26.20%。(2)NDVI指数和蒸散量实测值之间呈现正相关关系。(3)湿地平均蒸散量空间变化呈出现东南低西北高的变化趋势,2018和2019年研究区月平均蒸散量分别为126.35和126.86 mm;变化率多位于-36~0 mm·a^(-1),其比例为27.90%。【结论】生长季科克苏湿地蒸散量时间尺度上7月最高,空间上分布受植被覆盖所控制,不同区域蒸散量的差异明显。

新疆阿勒泰科克苏湿地自然保护区生态服务价值评价

利用市场价值法和替代法,对新疆阿勒泰科克苏湿地自然保护区直接使用价值(包括提供食物和原材料、科研文化、生态旅游)进行评价;采用市场价值法、影子工程法、碳税法、恢复使用法、替代花费法和替代法,对新疆阿勒泰科克苏湿地自然保护区间接使用价值(包括供水与蓄水、涵养水源和调蓄洪水、固碳释氧、水质净化、保育土壤、物种保育和栖息地)进行了量化评价。结果表明,科克苏湿地自然保护区总使用价值为13.15×108元,直接使用价值为1.45×108元,间接使用价值为11.70×108元,间接使用价值是直接使用价值的8.07倍,单位面积提供的使用价值为42 879.97元/hm2。

西天山科克苏河一带中新元古代碳酸盐岩沉积环境

新疆特克斯县科克苏河一带中—新元古代地层碳酸盐岩极为发育,但研究程度低,长期以来以群代组。通过1∶5万区调工作对本区基本层序调查和相分析,将该套地层解体。指出中—新元古代地层碳酸盐岩形成于“构造碳酸盐台地”的沉积环境,同时对角砾状灰岩的成因进行了探讨。