帕隆藏布江中游地壳剥露特征

涂继耀; 季建清; 钟大赉; 周晶

doi:10.19509/j.cnki.dzkq.2021.0260

帕隆藏布江中游地壳剥露特征

doi: 10.19509/j.cnki.dzkq.2021.0260

涂继耀^{1, 2,},
季建清¹,
钟大赉³,
周晶¹

1.
北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室, 北京 100871
2.
中国地震局地球物理研究所, 北京 100081
3.
中国科学院地质与地球物理研究所岩石圈演化国家重点实验室, 北京 100029

基金项目:

中国地震局地球物理研究所基本科研业务费专项 DQJB20K37

国家自然科学基金项目 41603055

详细信息

作者简介:
涂继耀(1988-), 男, 助理研究员, 主要从事构造地质学与同位素年代学研究工作。E-mail: 406962923@qq.com

中图分类号: P542;P597.3
计量
- 文章访问数: 515
- PDF下载量: 47
- 被引次数: 0
出版历程
- 收稿日期: 2021-05-12
- 网络出版日期: 2022-09-07

Crust erosion characteristics in the middle reach of the Purlung Tsangpo River

1.
Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China
2.
Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
3.
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China

摘要

摘要:
为揭示东喜马拉雅构造结演化过程, 也为未来可能重大工程建设提供基础地质资料, 对帕隆藏布江中游9块基岩样品进行了黑云母⁴⁰Ar/³⁹Ar测年, 并利用"Pecube"软件对该地区的地壳剥露速率进行半定量计算。样品黑云母⁴⁰Ar/³⁹Ar年龄范围为103~12.5 Ma, 对应地壳剥露速率范围为0.068~0.50 km/Ma。帕隆藏布江流域地壳剥露速率具有明显的东西差异特征, 下游(西段)地壳剥露速率显著高于中游(东段)。年龄数据及其模拟计算结果表明, 相对于东喜马拉雅构造结内部, 帕隆藏布江中游流域地壳剥露活动较弱且较稳定。雅鲁藏布江对帕隆藏布江的袭夺, 使得帕隆藏布下游(西段)重新进入河流演化幼年阶段, 河流快速下切剥蚀可能是导致该地区地壳剥露速率东西差异的原因。
- 东喜马拉雅构造结 /
- 帕隆藏布江 /
- 黑云母⁴⁰Ar/³⁹Ar /
- 地壳剥露 /
- 河流演化
Abstract:
To reveal the tectonic evolution process of the eastern Himalayan syntaxis and provide basic geological data for probable significant engineering construction, this study reports 9 biotite ⁴⁰Ar/³⁹Ar ages in the middle reach of the Purlung Tsangpo River and semiquantitatively calculates the rock erosion rates represented by these ages using the modeling code "Pecube". The measured biotite ⁴⁰Ar/³⁹Ar ages range from 103-12.5 Ma, corresponding to erosion rates ranging from 0.068-0.5 km/Ma. The rock erosion rates of the Purlung Tsangpo River have obvious differences between the western and eastern sections, which are characterized by the downstream section (western section) being significantly higher than that of the middle section (eastern section). Ages and simulation results show that in contrast to the eastern Himalayan syntaxis, the crust erosion rate in the middle reach of the Purlung Tsangpo River is lower and stable. The Purlung Tsangpo River was captured by the Yarlung Tsangpo River, which allowed the Purlung Tsangpo River downstream (western section) to change into a youth stage of fluvial geomorphological evolution again.The rapid river incised likely resulted in the erosion rate differences between the western and eastern sections.
- the eastern Himalayan syntaxis /
- Purlung Tsangpo River /
- biotite ⁴⁰Ar/³⁹Ar /
- crust erosion /
- river evolution

HTML全文

图 1 青藏高原印度板块大地构造框架图(a)以及东喜马拉雅构造结地质简图(b)

Figure 1. Generalized tectonic map of Indian Plate and Tibetan Plateau (a), Simplified geologic map of eastern Himalayan syntaxis (b)

下载: 全尺寸图片幻灯片

图 2 帕隆藏布江流域数字地貌及采样位置图

Figure 2. Digital geomorphological map of Purlung Tsangpo river basin and sample locations

下载: 全尺寸图片幻灯片

图 3 各样品黑云母⁴⁰Ar/³⁹Ar坪年龄图

Figure 3. ⁴⁰Ar/³⁹Ar plateau ages of biotite concentrates

下载: 全尺寸图片幻灯片

图 4 黑云母⁴⁰Ar/³⁹Ar年龄高程关系

Figure 4. Relationship between biotite ⁴⁰Ar/³⁹Ar ages and elevations

下载: 全尺寸图片幻灯片

图 5 河流地貌形态样品年龄对比图

a.样品实测年龄、最吻合剥露速率对比图；b.帕隆藏布江河流纵剖面图；c.帕隆藏布江不同位置河流横剖面图

Figure 5. River morphology and age contrast

下载: 全尺寸图片幻灯片

表 1 样品信息及年龄值

Table 1. Sample information and chronology data

样品名	经度	纬度	海拔/m	岩性	黑云母⁴⁰Ar/³⁹Ar坪年龄/Ma	2σ误差/Ma	MSWD值
11318-01	E96.053°	N29.735°	3 067	闪长岩	100.14	0.82	0.32
11318-02	E96.046°	N29.731°	3 090	闪长岩	102.57	0.63	0.38
11318-03	E95.985°	N29.753°	2 962	闪长岩	76.23	0.40	0.91
11318-04	E95.916°	N29.784°	2 896	闪长岩	47.65	0.40	0.17
11318-05	E95.835°	N29.811°	2 820	闪长岩	36.61	0.60	0.61
11318-06	E95.788°	N29.837°	2 752	闪长岩	20.87	0.22	0.16
11318-07	E95.679°	N29.898°	2 716	闪长岩	22.19	0.27	0.82
11318-10	E95.617°	N29.907°	2 680	闪长岩	23.25	0.92	1.03
11318-11	E95.401°	N29.937°	2 558	片麻岩	12.49	0.69	0.19

下载: 导出CSV

表 2 各模拟系列信息及计算结果

Table 2. Information of several simulation series and calculate results

模拟系列	经度范围	纬度范围	对应样品编号	模拟起始时间/Ma	最吻合剥露速率/(km·Ma^-1)	最吻合计算年龄/Ma	实测年龄/Ma
1	E96.02°~96.08°	N29.6°~29.9°	11318-01, 02	110	0.068	101	100.14，102.57
2	E95.95°~96.02°	N29.6°~29.9°	11318-03	90	0.09	76	76.23
3	E95.88°~95.95°	N29.6°~29.9°	11318-04	60	0.14	48	47.65
4	E95.81°~95.88°	N29.6°~29.9°	11318-05	50	0.18	37	36.61
5	E95.50°~95.81°	N29.7°~30.0°	11318-06, 07, 10	30	0.30	22	20.87，22.19，23.25
6	E95.30°~95.50°	N29.8°~30.1°	11318-11	20	0.50	12	12.49

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