新疆天山南部北轮台断裂带晚第四纪活动速率

引用本文

姚远, 宋和平, 陈建波, 李帅, 贾海梁. 新疆天山南部北轮台断裂带晚第四纪活动速率[J]. 地震地质, 2018,40(1): 71-86.
YAO Yuan, SONG He-ping, CHEN Jian-bo, LI Shuai, JIA Hai-liang. LATE QUATERNARY CRUSTAL SHORTENING RATE OF THE BEILUNTAI FAULT IN SOUTHERN TIAN SHAN, XINJIANG[J]. SEISMOLOGY AND GEOLOGY, 2018,40(1): 71-86. 复制到剪切板

DOI:10.3969/j.issn.0253-4967.2018.01.006
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新疆天山南部北轮台断裂带晚第四纪活动速率

姚远¹, 宋和平¹, 陈建波¹, 李帅¹, 贾海梁²

1新疆维吾尔自治区地震局, 乌鲁木齐 830011

2 西安科技大学建筑与土木工程学院, 西安 710000

〔作者简介〕姚远, 男, 1988年生, 2012年于中国地质大学(武汉)工程学院获得硕士学位, 工程师, 主要从事第四纪地质、构造地质方面的研究工作, 电话: 0991-3853817, E-mail: yy8096658@126.com。

收稿日期: 2017-11-15

基金项目: 地震科技星火计划(XH17042Y)、北轮台断裂东段 1︰5万地质填图项目与国家自然科学基金(41702334)共同资助

摘要

北轮台断裂是1条全新世活动断裂, 为南天山与塔里木盆地的分界断裂。晚第四纪以来, 北轮台断裂的持续活动使得多期洪积地貌面发生了断错变形与褶皱隆升。利用高精度差分GPS, 对北轮台断裂阿克艾肯段和砖厂段内的多期地貌面的断层陡坎形态进行了测量。通过大比例尺活动断层填图发现, 阿克艾肯段以逆冲作用为主, 而砖厂段则是以褶皱隆升为主。利用光释光测年方法, 分别得到了不同期次地貌面(Fan4, Fan3b, Fan3c和Fan2)的年龄, 发现自Fan4地貌面形成以来, 阿克艾肯段的地壳缩短速率(约2.4mm/a)基本保持恒定; 同时, 晚第四纪以来砖厂段的SN向地壳缩短速率为1.43~1.81mm/a, 较阿克艾肯段有明显下降, 推测北轮台断裂带的SN向地壳缩短速率由西向东递减。综合对比南天山山前的逆断裂-褶皱带体系, 同样反映出地壳缩短速率由西向东递减的特征。

关键词: 天山; 北轮台断裂带; 逆冲变形; 褶皱变形; 晚第四纪

中图分类号:P315.2 文献标志码:A 文章编号:0253-4967(2018)01-0071-16

LATE QUATERNARY CRUSTAL SHORTENING RATE OF THE BEILUNTAI FAULT IN SOUTHERN TIAN SHAN, XINJIANG

YAO Yuan¹, SONG He-ping¹, CHEN Jian-bo¹, LI Shuai¹, JIA Hai-liang²

1 Earthquake Agency of Xinjiang Uygur Autonomous Region, Urumqi 830011, China

2 School of Architecture and Civil Engineering, Xi'an University of Science and Technology, Xi'an 710000, China

Abstract

The Beiluntai Fault is a Holocene active fault. It is the boundary between southern Tian Shan and Tarim Basin. Since the late Quaternary, steady activities of the Beiluntai fault have resulted in offsets, folds, and uplift of pluvial terraces. We used the high-resolution RTK topographic surveys to reveal that the fault scarp morphology on the Akeaiken(Ak)segment and Zhuanchang(Zc)segment of the Beiluntai fault. We found that the crustal shortening of Ak and Zc segments are dominated by thrusting and folding-uplift, respectively. We employed th optically stimulated luminescence(OSL)dating method to develop a new chronology for the different pluvial terraces, indicating that they formed at 49.14~58.51, 27±3, 13.72~14.64, 7.13±0.88, (3.32±0.43)ka, respectively. These data permitted to estimate the crustal shortening rate(about 2.4mm/a)remains largely constant on the Ak segment, while the crustal shortening rate of Zc segment was 1.43~1.81mm/a since the Fan4 pluvial terraces was abandoned. Compared with the Ak segment, the crustal shortening rate of the Zc segment declined obviously. This shows that the NS-trending crustal shortening rate of the Beituntai fault decreased gradually from west to east. A comprehensive comparison of the reverse fault-fold belt system in the front of southern Tian Shan also indicates that the crustal shortening rate drops from west to east.

Keyword: Tian Shan; Beiluntai fault; thrust; fold; late Quaternary

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0 引言

天山位于欧亚大陆腹地, 是晚新生代以来印度板块与欧亚板块剧烈碰撞的产物, 也是新生代大陆内部变形和强震活动最为强烈的地区之一, 夹持于塔里木盆地与准噶尔盆地2个构造稳定体之间。相关学者的研究成果表明(Abdrakhmatov et al., 1996; Burchfiel et al., 1999; 王琪等, 2000; 张培震等, 2013), 天山地区的构造变形主要发生在其内部和两侧山前。天山两侧山前分布了一系列的 “ 薄皮构造” , 是天山的主体沿根部的逆断裂向南北两侧逆冲, 形成了多排活动逆冲-褶皱带(Avouac et al., 1993; 邓起东等, 2000; 杨晓平等, 2012; Li et al., 2013), 如北天山山前的齐古褶皱带、霍尔果斯-玛纳斯-吐谷鲁褶皱带和安集海-独山子褶皱带(冯先岳, 1985; 1986; Hendrix et al., 1994; Yin et al., 1998; 邓起东等, 1999)以及南天山山前的秋里塔格褶皱带、喀什褶皱带、柯坪推覆构造和阿图什褶皱带(邓起东等, 2000)。相关学者对天山的构造变形的工作取得了一系列的研究成果, 对不同地区不同时间段的滑动速率和缩短量均开展了详细讨论。

新生代以来天山地区的隆升和地壳缩短等定量参数的确定是研究天山构造变形的重要数据, 对认识天山造山带的地球动力学问题有重要意义。天山两侧及内部的GPS监测数据显示(Reigber et al., 2001; 张培震等, 2003), 76° E附近(喀什一带)的天山西段地壳运动速率为20mm/a, 而87° E附近(库尔勒一带)的天山东段地壳运动速率为4mm/a(王琪等, 2000), 表明天山东西2段现今的运动速率有明显的差异。南天山山前推覆构造带的地壳缩短速率同样具有很大的差异, 如柯坪逆冲推覆构造带的地壳缩短速率为15.4~17.3mm/a(杨晓平等, 2006a)、库车逆断裂-褶皱带的地壳缩短速率为10.4~14.2mm/a(杨晓平等, 2008), 运动强度由西向东依次降低。近年来, 对西南天山GPS站点的加密以及测量精度的提升、积累, 基于更高密度、精度的GPS观测结果; Zubovich等(2010)发现天山作为典型的板内造山带, 具有连续分布式的地壳形变特征, 这使得整个天山的地壳形变速率很大一部分被天山内部和山间盆地的变形所吸收, 其GPS速度剖面(黄伟亮等, 2015; Huang et al., 2015)在横跨天山内部的一系列山间盆地时出现了陡变且连续的速度梯度带, 说明山间盆地内部的一系列断层对整体应变的调节、吸收, 例如: 昭苏盆地、伊犁盆地以及伊塞克湖盆地。而在库车坳陷以东的天山地区, GPS站点数量明显减少, 无法通过GPS速度场来判定构造变形的活动特征及习性。这一地区盆山结合处的新生代构造是何种变形方式?其滑动速率又是如何?与西南天山相比地壳缩短速率是怎样?

为了探讨上述问题, 本文对库车坳陷以东的北轮台断裂带进行了定量研究。北轮台断裂是塔里木盆地与南天山的界线断裂, 同时也是库车逆断裂-褶皱带的根部控制断裂, 全长约200km。GPS观测资料表明, 北轮台断裂向S的逆冲缩短速率为(4.7± 2.5)mm/a(杨少敏等, 2008), 但其变形量、滑动速率和变形特征都不清楚。我们近期完成了北轮台断裂带的 1︰5万活动构造地质填图, 对南天山东段山前逆断裂-褶皱带的形态和特征有了更近一步认识; 利用高精度差分GPS测量、计算逆断裂-褶皱带的地壳缩短, 讨论各段的变形速率及其在天山形成中的构造意义。

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	图 1 天山南部东段地质构造图(a)和缩略图(b) SSD 松树达坂断裂, HLS 霍拉山断裂, YQN 焉耆盆地南缘断裂, BLT 北轮台断裂, TZK 特孜阔勒断裂; ①夏尔木背斜, ②哈尔莫墩背斜, ③阿尔夏特背斜, ④库车坳陷Fig. 1 Simplified geologic map of eastern part of southern Tian Shan.

1 北轮台断裂的构造地质背景

南天山的构造运动强烈, 各时期亦有明显差异。元古代发生了较广泛的构造运动, 使元古代地层褶皱断裂, 并伴有大量岩浆侵入活动, 构成了褶皱基底。古生代构造运动更加广泛且强烈, 使早期的褶皱断裂再次褶皱隆起, 使得天山地槽区遭受褶皱回返。中新生代新构造运动更加显著, 基底断裂继续活动, 天山快速隆升。喜马拉雅运动使得塔里木地台急剧下降, 沉积巨厚的堆积。新生代以来塔里木盆地北缘的南天山山体开始快速隆升, 使得山前发育了一系列的山前逆断裂-褶皱带。根据相关学者的研究成果(张培震等, 1996)库尔勒一带新生代地层的最大厚度为2i162m, 表明新生代以来南天山剧烈的构造活动。

北轮台断裂最新活动痕迹主要位于南天山山前1~4km的范围内, 沿断裂切割晚更新世和全新世洪积扇, 并形成高度不等的断层陡坎(邓起东等, 2001; 杨晓平等, 2004; 姚远, 2017)。本次研究集中在第四纪地貌面保存完好、活动断裂遗迹保存完整的阿克艾肯段和砖厂段(图1)。阿克艾肯段位于库尔楚西北10km处, 地表断层出露长度8km, 分布宽度约4km, 走向近EW, 属于N倾的逆冲断层, 断层倾角一般在30° ~50° ; 砖厂段位于库尔勒市西北18km, 地表出露长度6km, 分布宽度约3km, 走向近NWW。

2 北轮台断裂地貌面划分

2.1 阿克艾肯段地貌面划分

在北轮台断裂阿克艾肯段, 断裂多次活动使得山前发育了多级地貌面, 冲沟的侵蚀冲刷分隔了遭受变形断错的不同级地貌面(图2b)。

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	图 2 阿克艾肯断裂段卫星影像(b)及解译图像(a)Fig. 2 Google Earth image of Ake’ aiken segment of the Beiluntai fault(b)and the interpreted geomorphic map of the Beiluntai fault showing the spatial extent of pluvial fans as well as the locations of topographic profiles measured on the surface and structural data(a).

阿克艾肯断裂段的各级地貌面沉积结构基本相似, 表现为一定厚度的冰水堆积物或冲洪积砾石层角度不整合覆盖在早更新世的西域砾岩上; 部分地貌面上(Fan5, Fan4, Fan3a)冲沟呈辫状分布, 切割较深, 因此认为这几期地貌面为洪积台地(图2b)。根据拔河高度以及地貌面特征, 将阿克艾肯断裂段的地貌面从高到低划分为5期, 分别为Fan5、 Fan4、 Fan3、 Fan2、 Fan1(图3a)。Fan5和Fan4洪积台地是阿克艾肯断裂段中最高一级地貌面, 仅局部分布在山前, 不整合覆盖在山前花岗岩体上, 拔河高度为70~105m; 由于该地貌面时代较老, 表面冲沟发育, 已不存在现今水流的侵蚀和堆积作用。Fan3洪积扇是阿克艾肯断裂段分布面积最大、保存最完整的一级地貌面(图3a), 主要分布在阿克艾肯沟和喀拉萨喀拉阿塔木沟两侧(图3a); Fan3洪积扇又可以细分为3个次级的地貌面Fan3a、 Fan3b和Fan3c, 拔河高度依次约为40m、 31m和13m。Fan2、 Fan1洪积扇为阿克艾肯断裂段最新堆积物质, 最大拔河高度3~5m。

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	图 3 砖厂断裂段卫星影像(b)及解译图像(a)(A-A’、 B-B’见图7)Fig. 3 Google Earth image of Zhuanchang segment of the Beiluntai fault(b), and the interpreted geomorphic map of the Beiluntai fault showing the spatial extent of pluvial fans as well as the locations of topographic profiles measured on the surface and structural data(a).

各地貌面上覆盖的冲洪积堆积物质由磨圆度较好的砾石层组成, 砾石之间充填花岗岩风化颗粒及中粗砂。砾石主要以花岗岩为主, 也含有一些灰岩和变质岩, 砾石的分选性较差, 大小混杂填充, 排列无序。各洪积扇表面较平整, 由风化破碎的花岗岩和花岗岩碎屑嵌套组成, 砾石表层发育1套灰褐色的戈壁漆, 是典型的干旱地区铺石状地貌面。Fan5和Fan4洪积台地的沉积层剖面中, 砾石排列无序, 大小混杂, 包含一定数量的巨砾, 说明该沉积层为冰川堆积的冰碛物(张培震等, 1995), 其形成时代远远老于其余几期地貌面。

2.2 砖厂段地貌面划分

北轮台断裂砖厂段断层以背斜的形式活动, 背斜的持续生长发育了多级地貌面, 大、小冲沟的形成使遭到变形隆升的地貌面被切割, 形成大小不一的 “ 倒三角” 台地(图3)。由于背斜活动速率较弱、冲刷较为严重等, 砖厂段仅保留3级地貌面; 根据地貌面测年结果, 将其与阿克艾肯断裂段的地貌面进行对应分类, 分别为: Fan4, Fan3b, Fan1(图3a)。Fan4为砖厂段最高一级地貌面, 分布面积较大, 表面被冲刷较严重, 冲沟发育, 地表堆积物质以砾石为主, 成分以花岗岩和灰岩为主, 砾石粒径为十几cm到几cm不等, 均匀平铺于地表; Fan3b是保存最为完好、面积分布最大的一级地貌面, 最大拔河高度12m; Fan1为最新形成的一级洪积扇, 大面积分布于推测枢纽的南侧。

3 地貌面的年龄

3.1 采样方法和样品测试

本次采用光释光(Optically Stimulated Luminescence, OSL)测年方法对阿克艾肯段以及砖厂段地貌面的形成年龄进行了限定。光释光测年是目前较为成熟的一种针对第四纪沉积物年龄测定的方法。尤其是在干旱、半干旱的南天山山前, 洪积扇的物质主要由冲积、洪积带来, 石英、长石等矿物信号能够晒退较快、较好, 比较适宜采用光释光测年方法。在阿克艾肯段山前不同级地貌面Fan3b、 Fan3c、 Fan2以及砖厂段Fan4、 Fan3b采集了11组光释光测年样品。在带有沉积水平层理的粉砂、细砂中, 利用不锈钢套管(20~30cm长)平行于沉积层以敲击方式采集样品。套管两头用黑色塑料袋做避光处理, 外部用胶带包裹锡箔纸, 完全隔绝光线2次照射。

样品的处理在中国地震局地壳应力研究所地壳动力学重点实验室完成, 样品均为粉砂及以下粒径, 故采取4~11μ m细颗粒组分进行试验测试。

3.2 年龄结果

在阿克艾肯断裂段的不同级地貌面上采集光释光年代样品BLT1— 8(图2, 4g, 4h; 表1), 以最新的几期洪积扇地貌面为主。未能在Fan3a扇面上采集到光释光(OSL)样品, 邓起东等(2001)利用宇宙成因核素¹⁰Be测得该地貌面的废弃年龄为(27± 3)ka; 在Fan3b扇面上开挖的探槽中得到了1组年代数据, 初步认为Fan3b洪积扇面的废弃年龄为(14.64± 1.81)ka(BLT8)。在Fan3c洪积扇面上的探槽及冲沟侧壁采取了6组光释光年代样品, 为静水沉积带水平层理的粉砂或风沉积分选性好的粉土, 6组样品的平均年龄(7.13± 0.88)ka为Fan3c地貌面被废弃的年龄(图5b)。在Fan2洪积扇面上发育的冲沟侧壁上采集1组粉砂光释光年代样品, 代表Fan2地貌面被废弃的年龄为(3.32± 0.43)ka。

砖厂断裂段仅发育3级地貌面, 在Fan4洪积扇上探槽及冲沟沟壁上采集的OSL年代样品(BLT9、 10), 认为该地貌面年龄为49.14~58.51ka; 在Fan3b地貌面的冲沟侧壁采集到光释光年代样品(BLT11), 其年龄为(13.72± 1.9)ka。

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图 4 北轮台断裂野外构造活动照片
a 阿克艾肯段断裂与地貌面; b 砖厂段变形地层; c 阿克艾肯段不同地貌面上的断层陡坎; d 阿克艾肯段Fan3c地貌面断层陡坎; e 砖厂段褶皱变形; f 探槽揭露出北轮台断裂及其倾角; g 光释光BLT5样品采样点; h 光释光BLT1样品采样点; 照片位置见图2, 3Fig. 4 Photographs of the Beiluntai fault scarps(view to scarps in c, d, e and f).

表1 北轮台断裂沉积物光释光年龄测定值 Table1 Optically stimulated luminescence dating of sediments from the Beiluntai fault

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	图 5 阿克艾肯断裂段不同地貌面断层陡坎剖面各剖面位置见图2b; A 断层陡坎侵蚀变化模型, B 各地貌面年龄数据Fig. 5 Fault scarp profiles of different landform surfaces on the Ake’ aiken fault segment.

4 讨论

4.1 阿克艾肯段和砖厂段的变形机制

北轮台断裂作为南天山山前的1条主要的盆山分界断裂, 具有特殊的变形机制。根据野外实地观察, 北轮台断裂的阿克艾肯段和砖厂段各有不同的变形机制(图5, 6)。阿克艾肯断裂段被断错的洪积台地表现出了几个基本特征(图5): 1)断层断错地貌面处形成了顺坡向的断层陡坎, 断层两盘洪积台地面未发现掀斜, 上、下盘近水平(图4d); 2)各级洪积台地的地形剖面在断层下盘近水平(图4c); 3)随着拔河高度的增加, 不同期次的洪积台地的断层陡坎高度逐渐增大(图4a)。这些特征表明自最老一级洪积台地(Fan5)形成以后, 北轮台断裂阿克艾肯段以逆冲断错为主要活动方式。

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	图 6 阿克艾肯断裂段地壳缩短随时间变化曲线 a地壳缩短变形计算模型Fig. 6 Crustal shortening increments versus time of Ake’ aiken fault segment.

砖厂断裂段与阿克艾肯段不同(图7), 其中Fan4洪积台地面的掀斜方向与下伏地层的掀斜变化近似一致(图4b), 地层倾角向S逐渐增大(图4e), 在靠近断层处倾角达到最大, 表明自Fan4洪积台地形成以来, 砖厂断裂段以背斜隆升为主要模式。

4.2 阿克艾肯断裂段各级地貌面缩短速率

从整个阿克艾肯断裂段的地形剖面形态可以看出, 地层的缩短变形主要是以断层逆冲抬升为主, 缩短变形的主要吸收区应该发生在断层的两侧, 利用Lavé 等(2000)提出的地壳缩短变形计算模型(图6a)对阿克艾肯断裂段的缩短量进行了计算。

阿克艾肯断裂段共发育5期地貌面, 而最高1期地貌面(Fan5)由于时代较老, 被侵蚀冲刷严重, 仅在洪积扇根部位残留一部分, 而最新的地貌面Fan2、 Fan1断层活动变形痕迹微弱, 因此未测量其断层陡坎位错。选取Fan4、 Fan3(a, b, c)2期地貌面计算阿克艾肯断裂段地壳缩短速率。

$\begin{matrix} d = u / sinθ (1) \end{matrix}$

以阿克艾肯断裂段断层陡坎为例, 可以通过式(1), 如图6a所示, 得到阿克艾肯段各级地貌面的地壳缩短量(表2)。式(1)中θ 角为断层的倾角, 阿克艾肯段断层的倾角约为30° (图4f); u为断层陡坎的垂直位错量, 实测得到各级地貌面的垂直位错(图5), Fan4、 Fan3(a, b, c)的垂直位错分别为67m、 37m、 22m、 9m; d为计算得到的地壳缩短量, 通过式(1)计算得到缩短量分别为60m、 30m、 26m、 18m。结合各地貌面的年龄结果, 可以得到自Fan4洪积扇面被废弃以来阿克艾肯断裂段不同时间段的平均缩短速率分别为(2.31± 0.41)mm/a、 (2.45± 0.24)mm/a、 (3.52± 0.43)mm/a和(2.56± 0.31)mm/a。因此, Fan4地貌面形成以来, 通过逆断裂变形吸收的缩短速率基本相同, 约为2.4mm/a; 而Fan3b洪积扇面形成后缩短速率略有增加。通过式(1)计算得到的阿克艾肯段自58ka以来的缩短量大致保持恒定( 图6); 因此, 结合不同地貌面断层陡坎剖面(图5), 可以认为自Fan4地貌面形成以来, 各级地貌面的位错量是以线性等比例累积的。

表2 阿克艾肯断裂段洪积台地变形参数表 Table2 Deformation values of pluvial fans platforms on Ake’ aiken fault segment

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	图 7 砖厂段背斜地貌面地形剖面各剖面位置见图3b; a为背斜地壳缩短模型Fig. 7 Geomorphic and topographic profile of Zhuanchang anticline.

4.3 砖厂段背斜SN向地壳缩短

从砖厂段背斜的几何形态(图7)中可以看出, 整个背斜的缩短吸收量主要集中在背斜核部, 背斜下部的古近纪、新近纪泥岩地层产状变化很大, 因此利用Woodward等(1985)提出的盲逆断层-背斜地壳缩短模型(图7a), 计算砖厂段地壳缩短变形量。背斜顶面(Fan4)曲线A— A'(图7)的长度与其在地面的垂直投影长度B— B'的差值基本等于背斜形成以来的地壳缩短量Δ L。

$\begin{matrix} ΔL = L - L' (2) \end{matrix}$

从图7中可以看到背斜北翼Fan4地貌面坡度仅3° , 在背斜核部地貌面坡度约为5° , 利用式(3)计算得到Fan4地貌面背斜顶面曲线长度L为2i647m。

式(3)中, $\begin{matrix} x 为背斜投影水平距离 (m), y \end{matrix}$ 为背斜投影垂直距离(m)。

砖厂段背斜的投影长度可利用式(4)计算得到, L'为2i553m。

故此, 可以得到砖厂段背斜自形成以来引起的地壳缩短量为: Δ L=L-L'=94m。结合Fan4地貌面的年龄结果(表1), 可以得到砖厂段背斜自形成以来, SN向地壳缩短速率为1.43~1.81mm/a。

北轮台断裂带在南天山山前向盆地逆冲变形的过程中发育了2种形式的断裂, 在阿克艾肯段以主逆断裂模式发育, 在砖厂段背斜抬升过程中发育大量的弯矩断层(图7)(Philip et al., 1983; Yeats, 1986; 邓起东等, 2000; 李安等, 2011); 这一系列弯矩断层主要发育在砖厂段背斜的核部, 反映出背斜在形成过程中的应力状态(图8)。

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	图 8 砖厂段背斜断层样式及成因(改自Philip et al., 1983; 李安等, 2011) a 背斜核部弯矩断层形成模式; b 弯矩断层成因Fig. 8 Model of the Zhuanchang anticline and its genesis(adapted from Philip et al., 1983 and Li An et al., 2011).

现场调查发现, 砖厂段背斜具有盲逆断裂-背斜隆起特征, 同时在背斜核部伴生了一系列的弯矩断层。根据Suppe(1983)和Erslev(1991)提出的变形背斜褶皱核部的顶端处在张应力环境, 其应力释放即造成在背斜顶部地表发生拉张破裂, 形成正断层, 而破裂也多发生在地层弯曲变形最大的地段即背斜的核部(图8b)。这些弯矩断层一般为浅表破裂(图8a), 延伸深度有限; 背斜形成时间越长, 受侵蚀作用影响越大, 因此一般不易在地表出现变形。

4.4 与邻区构造变形速率的对比

北轮台断裂作为南天山与塔里木盆地的分界逆断裂, 其缩短速率可以很好地反映天山与盆地的相对运动趋势。塔里木盆地北部发育了1组逆断裂-褶皱带体系, 绵延1i200余km, 由东向西依次为北轮台断裂带、南天山中段库车坳陷、柯坪逆冲推覆构造带和喀什活动逆断裂-褶皱带。晚第四纪以来南天山中段的地壳缩短速率为4.5~14mm/a(Allen et al., 1999; 杨晓平等, 2008), 其中库车坳陷SN向的地壳缩短速率为5.0~7.0mm/a(吴传勇等, 2006)。杨晓平等(2006b)发现柯坪逆冲推覆构造带的地壳缩短量为40~45km, 得到该构造带自形成以来其地壳缩短速率为15.4~17.3mm/a。76° E附近(喀什一带)的南天山山前发育了喀什活动逆断裂-褶皱带, 该褶皱带晚第四纪以来的地壳缩短速率为10mm/a(沈军等, 2001; 陈杰等, 2011; 李涛等, 2011), 其北侧的纳伦盆地以北地区的晚第四纪地壳缩短速率为11mm/a(Thompson et al., 2002), 把两者相加得到该段天山地区的地壳缩短速率为21mm/a。而据南天山地区的GPS观测数据获得该区段的地壳缩短速率为20mm/a(王琪等, 2001), 与上述地质分析结果一致, 因此该段的地壳缩短速率为20~21mm/a。综合以上数据, 揭示出塔里木盆地北侧的一系列逆断裂-褶皱体系的地壳缩短速率由西向东呈现依次降低的现象; 结合杨少敏等(2008)的GPS研究成果, 塔里木地块相对于稳定欧亚大陆以0.520i3(° )/Ma的速度作顺时针旋转, 这一数据很好地对应了南天山山前的逆断裂-褶皱带的地壳缩短速率由西向东依次降低的特点(图9)。

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	图 9 天山南部山前逆断裂-褶皱体系SN向地壳缩短速率Fig. 9 NS-directed crustal shortening rates of of the reverse fault-fold system in southern Tian Shan.

5 结论

北轮台断裂带是南天山与塔里木盆地之间的1条分界断裂, 第四纪以来北轮台断裂带活动性明显, 位于断裂带中部的阿克艾肯段和东部的砖厂段完好地保留了多期第四纪地貌面。阿克艾肯段共保留了5期清晰的地貌面, 伴随着断裂的活动, 不同期次的地貌面上均保存了断裂的活动痕迹, 该段断裂以逆冲断错为主, 发育了一系列 “ 高大” 的断层陡坎, 最大累积高度可达67m; 晚第四纪以来砖厂段断裂活动性相对较弱, 仅保留3期地貌面, 通过对变形地貌面进行测量及下伏地层倾角的研究, 判定砖厂断裂段以背斜隆升为主要的生长模式, 并在背斜核部发育一系列的弯矩断层。

根据不同地貌面的变形量并结合各地貌面的年龄, 计算得到了阿克艾肯段和砖厂段的地壳缩短速率。结果表明, 晚更新世以来阿克艾肯段的地壳缩短速率约2.4mm/a, 基本保持恒定, 同时各级地貌面也是以线性等比例累积位错量; 晚更新世以来砖厂段SN向的地壳缩短量为94m, 缩短速率为1.43~1.81mm/a, 比阿克艾肯段有明显的降低, 说明北轮台断裂的缩短速率由西向东递减。综合对比南天山山前的一系列逆断裂-褶皱带体系, 其SN向的地壳缩短速率也表现出明显的由西向东递减的特征, 这一特征也与现今所观测的GPS数据有很好的一致性。

致谢巴音郭楞蒙古自治州地震局对于本次活断层填图工作给予了大力支持, 审稿专家对本文提出的意见和建议完善了文章内容, 在此一并致谢。

The authors have declared that no competing interests exist.

参考文献

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[1]	陈杰, 李涛, 李文巧, 等. 2011. 帕米尔构造结及邻区的晚新生代构造与现今变形[J]. 地震地质, 33(2): 241—259. doi: DOI: 103969/j. issn. 0253-4967. 2011. 02. 001. CHEN Jie, LI Tao, LI Wen-qiao, et al. 2011. Late Cenozoic and present tectonic deformation in the Pamir salient, northwestern China[J]. Seismology and Geology, 33(2): 241—259(in Chinese). [本文引用:1]
[2]	邓起东, 冯先岳, 张培震, 等. 1999. 乌鲁木齐山前坳陷逆断裂-褶皱带及其形成机制[J]. 地学前缘, 6(4): 191—201. DENG Qi-dong, FENG Xian-yue, ZHANG Pei-zhen, et al. 1999. Reverse Fault and fold zone in the Urumqi range-front depression of the northern Tianshan and its genetic mechanism[J]. Earth Science Frontiers, 6(4): 191—201(in Chinese). [本文引用:1]
[3]	邓起东, 冯先岳, 张培震, 等. 2000. 天山活动构造 [M]. 北京: 地震出版社: 42—60. DENG Qi-dong, FENG Xian-yue, ZHANG Pei-zhen, et al. 2000. Active Tectonics of the Chinese Tianshan Mountains [M]. Seismological Press, Beijing: 42—60(in Chinese). [本文引用:1]
[4]	邓起东, Molnar P, Brown E T, 等. 2001. 天山南缘北轮台断裂库尔楚段晚第四纪的最新活动和滑动速率[J]. 内陆地震, 15(4): 289—298. DENG Qi-dong, Molnar P, Brown E T, et al. 2001. Latest activity and slip rate of Kuerchu segment of Beiluntai Fault in south edge of Tianshan, China since late Pleistocene[J]. Inland Earthquake, 15(4): 289—298(in Chinese). [本文引用:1]
[5]	冯先岳. 1985. 论新疆地震地质特征[J]. 地震地质, 7(2): 35—44. FENG Xian-yue. 1985. Seismogeological characteristics of the Xinjiang area[J]. Seismology and Geology, 7(2): 35—44(in Chinese). [本文引用:1]
[6]	冯先岳. 1986. 天山的活动断层[J]. 中国地震, 2(2): 84—89. FENG Xian-yue. 1986. The active faults in Tianshan Mountains[J]. Earthquake Research in China, 2(2): 84—89(in Chinese). [本文引用:1]
[7]	黄伟亮, 杨晓平, 李安, 等. 2015. 焉耆盆地北缘和静逆断裂-褶皱带中晚第四纪变形速率[J]. 地震地质, 37(3): 675—696. doi: DOI: 103969/j. issn. 0253-4967. 2015. 03. 002. HUANG Wei-liang, YANG Xiao-ping, LI An, et al. 2015. Late Pleistocene shortening rate on the northern margin of Yanqi Basin, southeastern Tian Shan, NW China[J]. Seismology and Geology, 37(3): 675—696(in Chinese). [本文引用:1]
[8]	李安, 杨晓平, 黄伟亮, 等. 2011. 焉耆盆地北缘哈尔莫敦背斜区的活动断裂及其形成机制[J]. 地震地质, 33(4): 789—803. doi: DOI: 103969/j. issn. 0253-4967. 2011. 04. 005. LI An, YANG Xiao-ping, HUANG Wei-liang, et al. 2011. Active faults of the Haermodun anticline and their formation mechanism in the north margin of the Yanqi Basin[J]. Seismology and Geology, 33(4): 789—803(in Chinese). [本文引用:1]
[9]	李涛, 陈杰, 肖伟鹏, 等. 2011. 利用变形河流阶地限定帕米尔北缘木什背斜的缩短、隆升和侧向扩展[J]. 地震地质, 33(2): 308—322. doi: DOI: 103969/j. issn. 0253-4967. 2011. 02. 005. LI Tao, CHEN Jie, XIAO Wei-peng, et al. 2011. Using deformation terraces to confine the shortening, uplift and lateral propagation of the Mushi anticline, northern margin of the Pamir[J]. Seismology and Geology, 33(2): 308—322(in Chinese). [本文引用:1]
[10]	沈军, 赵瑞斌, 李军, 等. 2001. 塔里木盆地西北缘河流阶地变形测量与地壳缩短速率[J]. 科学通报, 46(4): 334—338. SHEN Jun, ZHAO Rui-bin, LI Jun, et al. 2001. Surveying of the deformed terraces and crust shortening rate in the northwestern Tarim Basin[J]. Chinese Science Bulletin, 46(12): 1043—1046. [本文引用:1]
[11]	王琪, 丁国瑜, 乔学军, 等. 2000. 天山现今地壳快速缩短与南北地块的相对运动[J]. 科学通报, 45(14): 1543—1547. WANG Qi, DING Guo-yu, QIAO Xue-jun, et al. 2000. Recent rapid shortening of crust across the Tianshan Mts. and relative motion of tectonic blocks in the north and south[J]. Chinese Science Bulletin, 45(21): 1995—1999. [本文引用:1]
[12]	王琪, 张培震, 牛之俊, 等. 2001. 中国大陆现今地壳运动和构造变形[J]. 中国科学(D辑), 31(7): 529—536. WANG Qi, ZHANG Pei-zhen, NIU Zhi-jun, et al. 2002. Present-day crustal movement and tectonic deformation in China continent[J]. Science in China(Ser D), 45(10): 865—874. [本文引用:1]
[13]	吴传勇, 沈军, 陈建波, 等. 2006. 新疆南天山库车坳陷晚第四纪以来地壳缩短速率的初步研究[J]. 地震地质, 28(2): 279—288. doi: DOI: 103969/j. issn. 0253-4967. 2006. 02. 011. WU Chuan-yong, SHEN Jun, CHEN Jian-bo, et al. 2006. Preliminary study of late quaternary crustal shortening rate along Kuqa depression in south Tianshan, Xinjiang[J]. Seismology and Geology, 28(2): 279—288(in Chinese). [本文引用:1]
[14]	杨少敏, 李杰, 王琪. 2008. GPS研究天山现今变形与断层活动[J]. 中国科学(D辑), 38(7): 872—880. YANG Shao-min, LI Jie, WANG Qi. 2008. The deformation pattern and fault rate in the Tianshan Mountains inferred from GPS observations[J]. Science in China(Ser D), 51(8): 1064—1080. [本文引用:1]
[15]	杨晓平, 邓起东, Molnar P, 等. 2004. 新疆天山南麓库尔楚西北冲洪积扇面的¹⁰Be年代[J]. 核技术, 27(2): 125—129. YANG Xiao-ping, DENG Qi-dong, Molnar P, et al. 2004. The¹⁰Be dating for surface of alluvium-diluvium fans in southern Tianshan piedmont[J]. Nuclear Techniques, 27(2): 125—129(in Chinese). [本文引用:1]
[16]	杨晓平, 邓起东, 张培震, 等. 2008. 天山山前主要推覆构造区的地壳缩短[J]. 地震地质, 30(1): 111—131. YANG Xiao-ping, DENG Qi-dong, ZHANG Pei-zhen, et al. 2008. Crustal shortening of major nappe structures on the front margins of the Tianshan[J]. Seismology and Geology, 30(1): 111—131(in Chinese). [本文引用:1]
[17]	杨晓平, 李安, 黄伟亮. 2012. 天山北麓活动褶皱带晚第四纪时期隆升的差异性[J]. 中国科学(D辑), 42(12): 1877—1888. YANG Xiao-ping, LI An, HUANG Wei-liang. 2013. Uplift differential of active fold zones during the late Quaternary, northern piedmonts of the Tianshan Mountains, China[J]. Science in China(Ser D), 56(5): 794—805. [本文引用:1]
[18]	杨晓平, 冉勇康, 程建武, 等. 2006 a. 柯坪推覆构造中的几个新生褶皱带阶地变形测量与地壳缩短[J]. 中国科学(D辑), 36(10): 905—913. YANG Xiao-ping, RAN Yong-kang, CHENG Jian-wu, et al. 2007. Measurement of terrace deformation and crustal shortening of some renascent fold zones within Kalpin nappe structure[J]. Science in China(Ser D), 50(1): 33—42. [本文引用:1]
[19]	杨晓平, 冉勇康, 宋方敏, 等. 2006 b. 西南天山柯坪逆冲推覆构造带的地壳缩短分析[J]. 地震地质, 28(2): 194—204. doi: DOI: 103969/j. issn. 0253-4967. 2006. 02. 003. YANG Xiao-ping, RAN Yong-kang, SONG Fang-min, et al. 2006 b. The analysis for crust shortening of Kalpin thrust tectonic zone, South-western Tianshan, Xinjiang, China[J]. Seismology and Geology, 28(2): 194—204(in Chinese). [本文引用:1]
[20]	姚远, 陈建波, 李帅, 等. 2017. 新疆天山北轮台断裂阿克艾肯段晚第四纪活动特征[J]. 第四纪研究, 37(3): 645—653. YAO Yuan, CHEN Jian-bo, LI Shuai, et al. 2017. Late-Quaternary activity characteristics of Akeaiken segment of Beiluntai fault belt at south of Tianshan, in Xinjiang[J]. Quaternary Sciences, 37(3): 645—653(in Chinese). [本文引用:1]
[21]	张培震, 邓起东, 杨晓平, 等. 1995. 天山北麓的冰水冲洪积地貌与新构造运动 [G]∥国家地震局地质研究所编. 活动断裂研究(4). 北京: 地震出版社: 63—78. ZHANG Pei-zhen, DENG Qi-dong, YANG Xiao-ping, et al. 1995. The ice alluvial geomorphology and neotectonic movement in northern slope of Tianshan[G]∥Institute of Geology, SSB. Research of Active Fault (4). Seismological Press, Beijing: 63—78(in Chinese). [本文引用:1]
[22]	张培震, 邓起东, 杨晓平, 等. 1996. 天山的晚新生代构造变形及其地球动力学问题[J]. 中国地震, 12(2): 127—140. ZHANG Pei-zhen, DENG Qi-dong, YANG Xiao-ping, et al. 1996. Late Cenozoic tectonic deformation and mechanism along the Tianshan Mountains, Northwestern China[J]. Earthquake Research in China, 12(2): 127—140(in Chinese). [本文引用:1]
[23]	张培震, 邓起东, 张竹琪, 等. 2013. 中国大陆的活动断裂、地震灾害及其动力过程[J]. 中国科学(D辑), 43(10): 1607—1620. ZHANG Pei-zhen, DENG Qi-dong, ZHANG Zhu-qi, et al. 2013. Active faults, earthquake hazards and associated geodynamic processes in continental China[J]. Science in China(Ser D), 43(10): 1607—1620(in Chinese). [本文引用:1]
[24]	张培震, 王敏, 甘卫军, 等. 2003. GPS观测的活动断裂滑动速率及其对现今大陆动力作用的制约[J]. 地学前缘, 10(S): 81—92. ZHANG Pei-zhen, WANG Min, GAN Wei-jun, et al. 2003. Slip rates along major active faults from GPS measurements and constraints on contemporary continental tectonics[J]. Earth Science Frontiers, 10(S): 81—92(in Chinese). [本文引用:1]
[25]	Abdrakhmatov K Y, Aldazhanov S A, Hager B H, et al. 1996. Relatively recent construction of the TienShan inferred from GPS measurements of present-day crustal deformation rates[J]. Nature, 384(6608): 450—453. [本文引用:1]
[26]	Allen M B, Vincent S J, Wheeler P T. 1999. Late Cenozoic tectonics of the Kepingtage thrust zone: interactions of the Tien Shan and Tarim Basin, Northwest China[J]. Tectonics, 18(4): 639—654. [本文引用:1]
[27]	Avouac J P, Tapponnier P, Bai M, et al. 1993. Active thrusting and folding along the northern Tien Shanand late Cenozoic rotation of the Tarim relative to Dzungaria and Kazakhstan[J]. Journal of Geophysical Research: Solid Earth, 98(B4): 6755—6804. [本文引用:1]
[28]	Burchfiel B C, Brown E T, Deng Q D, et al. 1999. Crustal shortening on the margins of the Tien Shan, Xinjiang, China[J]. International Geology Review, 41(8): 665—700. [本文引用:1]
[29]	Erslev E A. 1991. Trishear Fault-propagation folding[J]. Geology, 19(6): 617—620. [本文引用:1]
[30]	Hendrix M S, Dumitru T A, Graham S A. 1994. Late Oligocene-early Miocene unroofing in the Chinese Tian Shan: An early effect of the India-Asia collision[J]. Geology, 22(6): 487—490. [本文引用:1]
[31]	Huang W L, Yang X P, Li A, et al. 2015. Late Pleistocene shortening rate on the northern margin of the Yanqi Basin, southeastern Tian Shan, NW China[J]. Journal of Asian Earth Sciences, 112: 11—24. [本文引用:1]
[32]	Lavé J, Avouac J P. 2000. Active folding of fluvial terraces across the Siwaliks Hills, Himalayas of central Nepal[J]. Journal of Geophysical Research: Solid Earth, 105(B3): 5735—5770. [本文引用:1]
[33]	Li T, Chen J, Thompson J A, et al. 2013. Quantification of three-dimensional folding using fluvial terraces: A case study from the Mushi anticline, northern margin of the Chinese Pamir[J]. Journal of Geophysical Research: Solid Earth, 118(8): 4628—4647. [本文引用:1]
[34]	Philip H, Meghraoui M. 1983. Structural analysis and interpretation of the surface deformations of the ElAsnam Earthquake of October 101980[J]. Tectonics, 2(1): 17—49. [本文引用:1]
[35]	Reigber C, Michel G W, Galas R, et al. 2001. New space geodetic constraints on the distribution of deformation in Central Asia[J]. Earth and Planetary Science Letters, 191(1-2): 157—165. [本文引用:1]
[36]	Suppe J. 1983. Geometry and kinematics of fault-bend folding[J]. American Journal of Science, 283(7): 684—721. [本文引用:1]
[37]	Thompson S C, Weldon R J, Rubin C M, et al. 2002. Late Quaternary slip rates across the central TienShan, Kyrgyzstan, central Asia[J]. Journal of Geophysical Research: Solid Earth, 107(B9): ETG 7-1—ETG7—32. [本文引用:1]
[38]	Woodward N B, Boyer S E, Suppe J. 1985. An Outline of Balanced Cross—Section[M]. 2nd ed. University of Tennessee, Knoxville, 11: 170. [本文引用:1]
[39]	Yeats R S. 1986. Active faults related to folding [M]∥Wallace R E. Active Tectonics. National Academy Press, Washington D. C. [本文引用:1]
[40]	Yin A, Nie S, Craig P, et al. 1998. Late Cenozoic tectonic evolution of the southern Chinese Tian Shan[J]. Tectonics, 17(1): 1—17. [本文引用:1]
[41]	Zubovich A V, Wang X Q, Scherba Y G, et al. 2010. GPS velocity field for the Tien Shan and surrounding regions[J]. Tectonics, 29(6): TC6014. [本文引用:1]

2011

0.0

陈杰, 李涛, 李文巧, 等. 2011. 帕米尔构造结及邻区的晚新生代构造与现今变形[J]. 地震地质, 33(2): 241—259. doi: DOI: 103969/j. issn. 0253-4967. 2011. 02. 001.

CHEN

Jie

, LI

Tao

, LI

Wen-qiao

, et al. 2011. Late Cenozoic and present tectonic deformation in the Pamir salient, northwestern China[J]. Seismology and Geology, 33(2): 241—259(in Chinese).

1999

0.0

邓起东, 冯先岳, 张培震, 等. 1999. 乌鲁木齐山前坳陷逆断裂-褶皱带及其形成机制[J]. 地学前缘, 6(4): 191—201.

DENG

Qi-dong

, FENG

Xian-yue

, ZHANG

Pei-zhen

, et al. 1999. Reverse Fault and fold zone in the Urumqi range-front depression of the northern Tianshan and its genetic mechanism[J]. Earth Science Frontiers, 6(4): 191—201(in Chinese).

0.0

2001

0.0

邓起东, Molnar

, Brown E

, 等. 2001. 天山南缘北轮台断裂库尔楚段晚第四纪的最新活动和滑动速率[J]. 内陆地震, 15(4): 289—298.

DENG

Qi-dong

, Molnar

, Brown E

, et al. 2001. Latest activity and slip rate of Kuerchu segment of Beiluntai Fault in south edge of Tianshan, China since late Pleistocene[J]. Inland Earthquake, 15(4): 289—298(in Chinese).

1985

0.0

冯先岳. 1985. 论新疆地震地质特征[J]. 地震地质, 7(2): 35—44.

FENG

Xian-yue

. 1985. Seismogeological characteristics of the Xinjiang area[J]. Seismology and Geology, 7(2): 35—44(in Chinese).

1986

0.0

2015

0.0

黄伟亮, 杨晓平, 李安, 等. 2015. 焉耆盆地北缘和静逆断裂-褶皱带中晚第四纪变形速率[J]. 地震地质, 37(3): 675—696. doi: DOI: 103969/j. issn. 0253-4967. 2015. 03. 002.

HUANG

Wei-liang

, YANG

Xiao-ping

, LI

, et al. 2015. Late Pleistocene shortening rate on the northern margin of Yanqi Basin, southeastern Tian Shan, NW China[J]. Seismology and Geology, 37(3): 675—696(in Chinese).

How strain is distributed and partitioned on individual faults and folds on the margins of intermontane basins remains poorly understood. The Haermodun(Ha) anticline, located along the northern margin of the Yanqi Basin on the southeastern flank of the Tian Shan, preserves flights of passively deformed alluvial terraces. These terraces cross the active anticline and can be used to constrain local crustal shortening and uplift rates. Geologic and geomorphic mapping, in conjunction with high-resolution dGPS topographic surveys, reveal that the terrace surfaces are perpendicular to the fold's strike, and display increased rotation with age, implying that the anticline has grown by progressive limb rotation. We combine 10 Be terrestrial cosmogenic nuclide(TCN) depth profile dating and optically stimulated luminescence(OSL) dating to develop a new chronology for the terraces along the Huangshui He since 550ka. Our in situ 10 Be dating of fluvial gravels capping strath terraces suggests a relationship between the formation and abandonment of the terraces and glacial climate cycles since the middle-late Pleistocene. These data indicate that the formation of the four terraces occurred at ~550, ~430, ~350, and~60ka. We suggest that episodes of aggradation were facilitated by high sediment supply during glacial periods, followed by subsequent incision that led to abandonment of these terraces during deglaciation. Combining uplift and shortening distance with ages, we found the vertical uplift gradually decreased from 0.43 to 0.11mm/a, whereas the shortening rate was constant at ~0.3mm/a since the anticline began to grow. The shortening rates of the Ha anticline from geomorphology agree with current GPS measurements, and highlight the importance of determining slip rates for individual faults in order to resolve patterns of strain distribution across intermontane belts.

焉耆盆地为南天山内部的一个山间盆地, 盆地北缘发育1排第四纪新生褶皱带, 即和静逆断裂-褶皱带.中晚第四纪以来, 由于和静逆断裂-褶皱带的持续活动使得在褶皱生长过程中形成的多期洪积地貌面发生反向掀斜变形.利用高精度差分GPS, 对褶皱带中部哈尔莫敦背斜区内的多期变形地貌面的地形形态进行了测绘, 判定背斜的生长主要以翼旋转为主.利用背斜北翼不同地貌面的反向掀斜角度, 分别计算了不同期次地貌面的隆升和缩短变形量.结合原地宇宙成因核素深度剖面法和光释光测年法, 对背斜区内的F 4 , F 3b , F 2 洪积台地面和T 1 阶地面的形成年龄进行了测定, 发现背斜在距今约550ka、428.3 -47.2 +57.6 ka和354.3 -34.8 +34.2 ka不同时段的平均隆升速率从 0.31±0.24mm/a下降至 0.15±0.02mm/a, 同时背斜北翼的翼旋转速度也呈逐渐减小的趋势.但背斜自起始变形开始, 缩短速率却大致保持恒定为约 0.3mm/a.而这一恒定的缩短速率与现今横跨和静逆断裂-褶皱带所观测的GPS速率具有很好的一致性, 说明在天山内部的哈尔莫敦背斜区, 短尺度的GPS速率可以代表长尺度的地壳应变速率, 同时反映出山体内部一系列断层和褶皱构造在吸收和调节整体变形量时也起到一定的作用.

2011

0.0

李安, 杨晓平, 黄伟亮, 等. 2011. 焉耆盆地北缘哈尔莫敦背斜区的活动断裂及其形成机制[J]. 地震地质, 33(4): 789—803. doi: DOI: 103969/j. issn. 0253-4967. 2011. 04. 005.

, YANG

Xiao-ping

, HUANG

Wei-liang

, et al. 2011. Active faults of the Haermodun anticline and their formation mechanism in the north margin of the Yanqi Basin[J]. Seismology and Geology, 33(4): 789—803(in Chinese).

2011

0.0

李涛, 陈杰, 肖伟鹏, 等. 2011. 利用变形河流阶地限定帕米尔北缘木什背斜的缩短、隆升和侧向扩展[J]. 地震地质, 33(2): 308—322. doi: DOI: 103969/j. issn. 0253-4967. 2011. 02. 005.

Tao

, CHEN

Jie

, XIAO

Wei-peng

, et al. 2011. Using deformation terraces to confine the shortening, uplift and lateral propagation of the Mushi anticline, northern margin of the Pamir[J]. Seismology and Geology, 33(2): 308—322(in Chinese).

Locating at eastern end of the Pamir Front Thrust(PFT),the Mushi anticline grows initiating from early-Pleistocene till now.The anticline,with a gentle south limb and steep north limb,outcrops Pliocene Atushi formation and lower-Pleistocene Xiyu formation.Topographic profiles and drainage pattern indicate the lateral growth of the anticline from west to east.Combining mapping data and seismic profiles from the neighboring area,we find the Mushi anticline is a detachment fold,with a total shortening of ～0.7km and a total uplift up to～1.5km.Northern part of the anticline is dominated by a series of wide,flat terraces.According to OSL samples,the age of the terrace T2a,T3and T4 is 15.8±2.4ka,55.1±10.3ka and 131.4±23.9ka respectively.Correlating with Marine Isotopic stages(MIS),the formation of terraces has some relationship with global climate change.As growing of the anticline,terrace surfaces deformed obviously,which is characterized by fault scarps,surface tilting or back-tilting,folding scarps and lateral tilting.Deforming patterns of the terrace surfaces indicate the Mushi anticline grows by limb rotation in late-Pleistocene.Using calculating models,we can confine the minimum shortening rate is 1.6±0.3mm/a and the minimum uplift rate is 1.9±0.3mm/a. Longitudinal profiles of terraces indicate the Mushi anticline grows laterally through limb rotation.According to relationship between uplift and lateral propagation,we can acquire a faster eastward lateral propagation rate of the anticline during the period of 131～16ka,with a rate about 14.6±3.6mm/a; however,since 16ka,the rate reduced to 1.7±0.3mm/a,implying the anticline tip stopped propagating to the east,and growing of the anticline was mainly dominated by lateral limb rotation in late Quaternary.

位于帕米尔前缘逆冲推覆体(Pamir Front Thrust,PFT)东端的木什滑脱背斜,是帕米尔弧形推覆构造带最前缘和最新的变形带。对地形横剖面、纵剖面和水系发育特征的分析表明,木什背斜总体上具有由西向东扩展生长的特征。在背斜核部及北翼发育数级开阔平坦的沿轴向展布的河流阶地,阶地可划分为4期。利用阶地堆积细颗粒石英光释光测年获得阶地面T2a、T3和T4的形成年龄分别为(15.8±2.40)ka、(55.1±10.3)ka、(131.4±23.9)ka。伴随背斜的生长扩展,河流阶地面发生了横向和纵向掀斜,并形成断层陡坎和褶皱陡坎。木什背斜晚第四纪的缩短和隆升主要是通过褶皱翼旋转机制进行的,估算其最小缩短速率为(1.6±0.3)mm/a,最小隆升速率为(1.9±0.3)mm/a。与此同时,沿轴向背斜发生了向东的侧向迁移和旋转。根据背斜垂直隆升与侧向扩展之间的关系,估算背斜在131～16ka期间向东的侧向迁移扩展速率较快,为 (14.6±3.6)mm/a; 自16ka至今,侧向迁移扩展速率迅速减小至(1.7±0.3)mm/a,背斜向东的迁移扩展可能已基本停止,而以侧向旋转为主。

2001

0.0

沈军, 赵瑞斌, 李军, 等. 2001. 塔里木盆地西北缘河流阶地变形测量与地壳缩短速率[J]. 科学通报, 46(4): 334—338.

SHEN

Jun

, ZHAO

Rui-bin

, LI

Jun

, et al. 2001. Surveying of the deformed terraces and crust shortening rate in the northwestern Tarim Basin[J]. Chinese Science Bulletin, 46(12): 1043—1046.

通过塔里木盆地西北缘穿越阿图什背斜的河流阶地变形测量和年代学研究,计算出该背斜带晚更新世末期以来的地壳缩短速率可达5～6mm/a,估计塔里木盆地北缘晚更新世末期以来的地壳缩短速率可达10 mm/a以上.

2000

0.0

王琪, 丁国瑜, 乔学军, 等. 2000. 天山现今地壳快速缩短与南北地块的相对运动[J]. 科学通报, 45(14): 1543—1547.

WANG

, DING

Guo-yu

, QIAO

Xue-jun

, et al. 2000. Recent rapid shortening of crust across the Tianshan Mts. and relative motion of tectonic blocks in the north and south[J]. Chinese Science Bulletin, 45(21): 1995—1999.

基于天山及塔里木地区1992~1999年间多次全球定位系统(GPS)大地测量,直接观测到跨天山西段(76° E)约20 mm/a的地壳快速缩短及天山东段(87° E)约4 mm/a的汇聚变形,且跨天山带的南北向汇聚变形从西到东递减.天山南缘GPS点所代表的现今运动方向基本与天山褶皱带走向正交,塔里木盆地整体上对天山褶皱带形成正向挤压.塔里木盆地内部变形较小或基本不变形,整体上作为刚性块体,以95.7° E, 40.3° N(甘肃省安西)为欧拉极,相对于稳定的西伯利亚地块作顺时针旋转,角速率为0.64° /Ma.哈萨克地台及准噶尔盆地间有明显相对运动,在亚洲构造运动格架上,准噶尔盆地可能是一个独立的活动地块.

2001

0.0

王琪, 张培震, 牛之俊, 等. 2001. 中国大陆现今地壳运动和构造变形[J]. 中国科学(D辑), 31(7): 529—536.

WANG

, ZHANG

Pei-zhen

, NIU

Zhi-jun

, et al. 2002. Present-day crustal movement and tectonic deformation in China continent[J]. Science in China(Ser D), 45(10): 865—874.

全球定位系统(GPS)揭示的中国大陆现今运动场清晰地表现出了以活动地块为单元的分块运动特征,不同的活动地块具有不同的运动和变形方式.GPS观测到的阿尔金断裂的左旋走滑速率仅(5.1±2.5)mm/a,龙门山断裂的挤压缩短速率为(6.7±3.0)mm/a,华南地块相对于欧亚大陆向东的运动速率是11～14 mm/a,这些结果均不支持青藏高原北部沿主要走滑断裂向东大规模挤出的假说.中国大陆以活动地块为单元的现今构造变形可能与大陆岩石圈的结构和性质有关,上地壳以脆性变形为主,下地壳和上地幔以粘塑性的流变为特征,从底部驱动着上覆脆性地块的整体运动.

2006

0.0

吴传勇, 沈军, 陈建波, 等. 2006. 新疆南天山库车坳陷晚第四纪以来地壳缩短速率的初步研究[J]. 地震地质, 28(2): 279—288. doi: DOI: 103969/j. issn. 0253-4967. 2006. 02. 011.

Chuan-yong

, SHEN

Jun

, CHEN

Jian-bo

, et al. 2006. Preliminary study of late quaternary crustal shortening rate along Kuqa depression in south Tianshan, Xinjiang[J]. Seismology and Geology, 28(2): 279—288(in Chinese).

2008

0.0

杨少敏, 李杰, 王琪. 2008. GPS研究天山现今变形与断层活动[J]. 中国科学(D辑), 38(7): 872—880.

YANG

Shao-min

, LI

Jie

, WANG

. 2008. The deformation pattern and fault rate in the Tianshan Mountains inferred from GPS observations[J]. Science in China(Ser D), 51(8): 1064—1080.

2004

0.0

杨晓平, 邓起东, Molnar

, 等. 2004. 新疆天山南麓库尔楚西北冲洪积扇面的¹⁰Be年代[J]. 核技术, 27(2): 125—129.

YANG

Xiao-ping

, DENG

Qi-dong

, Molnar

, et al. 2004. The¹⁰Be dating for surface of alluvium-diluvium fans in southern Tianshan piedmont[J]. Nuclear Techniques, 27(2): 125—129(in Chinese).

2008

0.0

杨晓平, 邓起东, 张培震, 等. 2008. 天山山前主要推覆构造区的地壳缩短[J]. 地震地质, 30(1): 111—131.

YANG

Xiao-ping

, DENG

Qi-dong

, ZHANG

Pei-zhen

, et al. 2008. Crustal shortening of major nappe structures on the front margins of the Tianshan[J]. Seismology and Geology, 30(1): 111—131(in Chinese).

We present the results of selected balanced cross-sections across four active reverse fault-fold belts at the front margins of the Chinese Tianshan,an intracontinental mountain belt formed in response to the India-Eurasia continental collision. It consists of Paleozoic,Mesozoic and Cenozoic strata in active fold-and-thrust belts at two sides of Tianshan, and the stratum in active fold belt changes younger from west fold-and-thrust belt to east. The middle part's structure is complicated in Kalpin active fold-and-fault belt,the width gradually diminishes towards east. At the west of Akesu city,the Kalpin active fold-and-thrust belt vanishes, but at the east part of Akesu city,the Kuche active fold-and-thrust belt emerges on the Tarim desert. In the middle section of the Kuche active fold-and-thrust belt near Baicheng County,the structure is most complicated,and the width is also maximal. The width of Kuche fold-and-thrust belt gradually decreases towards east,and disappears near 85° longitude line. But at the northern piedmont of Tianshan,the Manas active fold-and-thrust belt presents itself approximately at the same longitude. The longitude of the west end of Turpan centre uplift active fold-and-thrust zone is approximately the longitude of the east end of the Manas active fold-and-thrust belt. The four active fold-and-thrust belts which we studied are located at the north and south sides of Tianshan Mountains. Two balanced cross-sections traverse the Kalpin active fold-and-fault belt and one crosses the Kuche fold-and-fault belt. Two balanced cross-sections cross the Manas active fold-and-thrust belt,and one balanced cross-section crosses the Turfan centre uplift zone. The crustal shortening of Kalpin fold-and-thrust belt is 40～45km,that of Kuche fold-and-thrust belt about 27～37km,and of Manas,Turpan centre uplift active fold-and-thrust belt are 8.5～10.5km and 6～7km,respectively. The four active fold-and-thrust belts at south and north Tianshan are not superposed in longitude. So their crustal shortenings approximately represent the minimal crustal shortening of Tianshan at different segments,and also reflect the reducing trend of crustal shortening from west to east. It is very difficult to calculate the crustal shortening across entire Tianshan,owing to deficiency of data about active reverse fault and strike-slip fault within Tianshan Mountains. If the time of initial deformation is the starting time of Xiyu conglomerate deposition(since 2.5Ma),and considering the shortening component on south-north direction of Bo-A NW strike-slip fault,the minimum crustal shortening rates at four segments of Tianshan would be 15.4～17.3mm/a,12.7～16.5mm/a,3.8～4.5mm/a and 2.3～2.7mm/a,respectively.

利用平衡地质剖面方法研究天山山前主要褶皱带的地壳缩短,其中3条平衡剖面分别横跨天山南簏的柯坪逆断裂-褶皱带和库车逆断裂-褶皱带,2条剖面横跨天山北簏的玛纳斯活动逆断裂-褶皱带,其余1条剖面横跨吐鲁番中央隆起逆断裂-褶皱带。柯坪活动逆断裂-褶皱带、库车逆断裂-褶皱带、玛纳斯逆断裂-褶皱带和吐鲁番盆地的地壳缩短量分别为40～45km、27～37km、8.5～10.5km和6～7km。天山山前活动逆断裂-褶皱带在EW向上互不重叠,它们的缩短量大致代表了该经度上新生代的最小地壳缩短量,反映出天山地壳缩短由西向东减小的趋势。假定天山山前活动逆断裂-褶皱带开始形成的时间为距今2.5Ma的西域砾岩沉积期,考虑到博阿断裂、塔拉斯-费尔干纳断裂在SN向上的缩短活动分量,上述4个地段的最小缩短速率分别为15.4～17.3mm/a、12.7～16.5mm/a、3.8～4.5mm/a和2.3～2.7mm/a。活动走滑断裂在天山内部特定位置向左偏转,走向由NW转为NWW,在断裂转折的部位走滑活动量转化为天山SN向的缩短变形。

2012

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杨晓平, 李安, 黄伟亮. 2012. 天山北麓活动褶皱带晚第四纪时期隆升的差异性[J]. 中国科学(D辑), 42(12): 1877—1888.

YANG

Xiao-ping

, LI

, HUANG

Wei-liang

. 2013. Uplift differential of active fold zones during the late Quaternary, northern piedmonts of the Tianshan Mountains, China[J]. Science in China(Ser D), 56(5): 794—805.

奎屯河和玛纳斯河横切天山北麓的独山子背斜和玛纳斯背斜,在背斜区分别形成7级和6级基座阶地,为晚第四纪以来独山子背斜和玛纳斯背斜褶皱隆起的构造地貌标志.在各阶地堆积物中系统采集了测年样品,用细颗粒光释光简单多片再生法(SMAR)测年.奎屯河T1阶地堆积物中采集到14C测年样品并测年.测年结果显示,它们均为晚更新世晚期以来的堆积物.阶地堆积物测年结果和西北地区距今200ka以来气候变化对比认为:玛纳斯河T1,T2,T3,T4和T5阶地的形成年代分别为距今6,8.5,10,14和32ka,奎屯河T1,T2,T3,T4,T5,T6和T7阶地的形成年代分别为距今1.7,14,20,25,32,50和100ka.玛纳斯河T4阶地和奎屯河T2阶地形成于距今14ka的晚更新世晚期.距今14ka以来玛纳斯河下切形成了3级基座阶地,而奎屯河下切只形成了1级基座阶地.独山子背斜最新一次褶皱隆升事件发生在距今1.7ka,玛纳斯背斜最新一次褶皱隆升发生在距今5ka.距今14ka以来的晚更新世晚期以来,独山子背斜、玛纳斯背斜的隆升量分别为40和95m,隆升速率分别为2.7和6.8mm/a.

2006

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杨晓平, 冉勇康, 程建武, 等. 2006 a. 柯坪推覆构造中的几个新生褶皱带阶地变形测量与地壳缩短[J]. 中国科学(D辑), 36(10): 905—913.

YANG

Xiao-ping

, RAN

Yong-kang

, CHENG

Jian-wu

, et al. 2007. Measurement of terrace deformation and crustal shortening of some renascent fold zones within Kalpin nappe structure[J]. Science in China(Ser D), 50(1): 33—42.

柯坪推覆构造是天山山前新生代以来逆冲和褶皱变形最强烈地段,构造变形不仅发生在醒目的5～6排中新生代褶皱带上,而且在褶皱山前现今冲洪积扇上形成几个新生褶皱.在野外用全站仪(TotalStation)测量了新生褶皱带内冲沟阶地地形纵剖面,同时采集了阶地堆积物中的测年样本.根据变形阶地的形成年代和缩短量,计算出4个新生褶皱的缩短速率分别为(0.1±0.03),(0.12±0.04),(0.59±0.18)和(0.26±0.08).新生褶皱的形成时代略晚于青藏高原0.14Ma的重大构造隆升事件,可能是天山山前褶皱带对这次构造事件远程效应.

2006

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杨晓平, 冉勇康, 宋方敏, 等. 2006 b. 西南天山柯坪逆冲推覆构造带的地壳缩短分析[J]. 地震地质, 28(2): 194—204. doi: DOI: 103969/j. issn. 0253-4967. 2006. 02. 003.

YANG

Xiao-ping

, RAN

Yong-kang

, SONG

Fang-min

, et al. 2006 b. The analysis for crust shortening of Kalpin thrust tectonic zone, South-western Tianshan, Xinjiang, China[J]. Seismology and Geology, 28(2): 194—204(in Chinese).

2017

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姚远, 陈建波, 李帅, 等. 2017. 新疆天山北轮台断裂阿克艾肯段晚第四纪活动特征[J]. 第四纪研究, 37(3): 645—653.

YAO

Yuan

, CHEN

Jian-bo

, LI

Shuai

, et al. 2017. Late-Quaternary activity characteristics of Akeaiken segment of Beiluntai fault belt at south of Tianshan, in Xinjiang[J]. Quaternary Sciences, 37(3): 645—653(in Chinese).

Large-scale thrust nappe system is distributed in the front of Tianshan. All of this thrust tectonic system are controlled by the reverse fault, such as the southern margin of the Junggar Fault in the north of Tianshan and the Beiluntai Fault in the south of Tianshan.The Beiluntai fault zone is the boundary between the Tarim Basin and the south Tianshan, and is a micro plate boundary polymerization, with a length of ca.120km, the latest deformation located in the proluvial fan and made different fault scarp. In order to accurately evaluate the fracture characteristics of Late Quaternary activity, the activities paragraph length, fault slip rate, the maximum total displacement and the latest activity of the era and a series of important quantitative data must be clarified. We carried out field geological investigation and measurement, excavated 2 large palaeoearthquake trench and collected some OSL samples in the Akeaiken Fault segment of Beiluntai Fault. Based on this data we have a new understanding of the characteristics of activities to provide the basic data for the judge with the regional seismic hazard analysis. The Akeaiken Fault segment is located in the piedmont alluvial fan of south of Tianshan, and the surface deformation traces is 8km. The strike of fault is EW, and the tendency is N and dip is 40~50 degrees. Since the Holocene, the activity of Akeaiken Fault segment is still strong, and it has formed a series of geological phenomena. There has been developed multi periods alluvial fan, and its major material source is intrusive granite in Cenozoic. The alluvial fan of most widely distributed is F3, and the fault scarps are mainly distributed in this alluvial fan. According to the result of OSL samples, the age of F3 alluvial fan is divided into two small periods(F3a and F3b)about 14.64卤1.81ka and 9.55卤1.48ka. The average vertical dislocations of the two fans are 29.0m and 10.7m. So, the average vertical slip rate since the Late Quaternary of F3a is 1.71~2.07mm/a and F3b is 0.97~1.32mm/a.We have evaluated the stratigraphic relationship of trench, and found two paleoseismic event occurred in the Akeaiken Fault segment since the Middle Holocene, and the event 鈪 is dating from 6.60ka to 7.15ka and the other event is after 4.05ka. The coseismic displacement of the event 鈪 is 2.5~3.5m. According to the sliding rate method(T=D/V), the characteristic earthquake recurrence period is 2.7ka.

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1996

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张培震, 邓起东, 杨晓平, 等. 1996. 天山的晚新生代构造变形及其地球动力学问题[J]. 中国地震, 12(2): 127—140.

ZHANG

Pei-zhen

, DENG

Qi-dong

, YANG

Xiao-ping

, et al. 1996. Late Cenozoic tectonic deformation and mechanism along the Tianshan Mountains, Northwestern China[J]. Earthquake Research in China, 12(2): 127—140(in Chinese).

2013

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张培震, 邓起东, 张竹琪, 等. 2013. 中国大陆的活动断裂、地震灾害及其动力过程[J]. 中国科学(D辑), 43(10): 1607—1620.

ZHANG

Pei-zhen

, DENG

Qi-dong

, ZHANG

Zhu-qi

, et al. 2013. Active faults, earthquake hazards and associated geodynamic processes in continental China[J]. Science in China(Ser D), 43(10): 1607—1620(in Chinese).

2003

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张培震, 王敏, 甘卫军, 等. 2003. GPS观测的活动断裂滑动速率及其对现今大陆动力作用的制约[J]. 地学前缘, 10(S): 81—92.

ZHANG

Pei-zhen

, WANG

Min

, GAN

Wei-jun

, et al. 2003. Slip rates along major active faults from GPS measurements and constraints on contemporary continental tectonics[J]. Earth Science Frontiers, 10(S): 81—92(in Chinese).

活动断裂的滑动速率是晚第四纪构造变形的定量描述,是制约和研究现今大陆动力过程的重要基础数据.地震地质学研究给出主要活动断裂的长期和平均运动水平,横跨断裂的GPS观测能够提供断裂的现今滑动速率.文中利用重大科学工程"中国地壳运动观测网络"的1 000多个GPS观测站的复测数据,计算中国大陆主要活动断裂的现今滑动速率.发现主要活动断裂的GPS滑动速率与晚第四纪滑动速率在运动方式和运动量上是大体一致的.从GPS观测到的断层滑动速率来看,中国大陆的大多数活动断裂的速率都在10 mm/a之下,而没有类似于板块边界的大于20～30 mm/a的滑动速率.这种现象意味着整个中国大陆的构造变形可能是分布式的,而不是仅仅集中在少数几条大型活动构造带上,沿主要活动断裂的刚性块体滑移可能不是构造变形的主要方式.现今构造变形的分块运动图像可能只是脆性上地壳的变形方式,中下地壳和上地幔的运动则以连续变形为特征,从下部驱动脆性上地壳的变形和运动,使得上部地壳的变形既表现出分块特征,又发生块内的变形."连续变形"理论模型能够更好地描述大陆内部的构造变形.

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1983

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