CENOZOIC FAULT ACTIVITY OF THE SOUTHERN SEGMENT OF THE LONGMENSHAN THRUST BELT：EVIDENCE FROM LOW-TEMPERATURE THERMOCHRONOLOGY DATA

doi:10.3969/j.issn.0253-4967.2013.03.005

Abstract

Abstract:

The Longmen Shan,located at the eastern margin of the Tibetan plateau,is a steep and high exhumation area. In recent years,the 2008 Wenchuan M_W7.9 earthquake and the 2013 Lushan M_S7.0 earthquake occurred,and researchers presented a lot of low-temperature thermochronology data of the Longmen Shan and adjacent area. In this paper,we provide 4 ZFT ages and 4 AFT ages for the southern segment of the Longmenshan Thrust Belt(LTB),where the low-temperature thermochronology data are still few. Combining with previous researches,we get the Cenozoic exhumation history of the Baoxing Massif,located at the southern segment of the LTB,and new knowledge about the Cenozoic activity of the southern segment of the LTB.The Baoxing Massif began quickly cooling in the early Cenozoic,with the cooling range exceeding 225℃,while the cooling range of the Pengguan Massif in the central segment of the Longmen Shan is between 185～225℃.The four AFT ages in the Baoxing Massif are between 2.7～5.0Ma,which are younger than that in the Pengguan Massif,and it indicates that the late-Cenozoic cooling rate of the Baoxing Massif is bigger than that of the Pengguan Massif. Under this assumption that the surface temperature is 15℃ and the paleo-geothermal gradient is 30℃/km,the average exhumation rate from 3～5Ma to present is about 0.63～1.17mm/yr. The low-temperature thermochronology data indicate that the differential exhumation is concentrated in the Beichuan-Yingxiu Fault and the Jiangyou-Guanxian Fault in the central segment of the LTB,while it is dispersed in a wider region along the two branches of the Shuangshi-Dachuan Fault and the faults and folds to the east,in the southern segment.

Key words: Lushan earthquake, Low-temperature thermochronology, eastern Tibet, Baoxing Massif, Longmen Shan

摘要：

龙门山位于青藏高原东边缘,地形陡变,剥蚀作用强烈。近年来先后经历了2008年汶川M_W7.9地震和2013年芦山M_S 7.0地震,多位学者对龙门山地区做了大量的低温热年代学研究。文中在研究程度相对薄弱的龙门山南段补充了4个锆石裂变径迹年龄和4个磷灰石裂变径迹年龄,结合前人的低温热年代学数据结果得出,宝兴杂岩从新生代早期开始快速冷却,降温幅度超过225℃,而龙门山中段的彭灌杂岩降温幅度为185～225℃。宝兴杂岩的4个裂变径迹年龄分布在2.7～5Ma,相对彭灌杂岩较年轻,表明晚新生代以来宝兴杂岩的冷却速率要高于彭灌杂岩。在地表温度为15℃和古地温梯度为30℃/km的假设下,宝兴杂岩距今3～5Ma以来的平均剥露速率为0.63 ～1.17mm/a。低温热年代学数据揭示出龙门山中段的差异剥蚀集中在北川-映秀断裂和江油-灌县断裂上,而南段的差异剥蚀分散在更宽范围内的双石-大川断裂(南、北2个分支)及其东侧的断层和褶皱。

关键词: 芦山地震, 低温热年代学, 青藏高原东缘, 宝兴杂岩, 龙门山

CLC Number:

P597

TAN Xi-bin, LEE Yuan-hsi, XU Xi-wei, CHEN Wen-yu, XU Chong, YU Gui-hua. CENOZOIC FAULT ACTIVITY OF THE SOUTHERN SEGMENT OF THE LONGMENSHAN THRUST BELT：EVIDENCE FROM LOW-TEMPERATURE THERMOCHRONOLOGY DATA[J]. SEISMOLOGY AND GEOLOGY, 2013, 35(3): 506-517.

谭锡斌, 李元希, 徐锡伟, 陈玟禹, 许冲, 于贵华. 低温热年代学数据对龙门山推覆构造带南段新生代构造活动的约束[J]. 地震地质, 2013, 35(3): 506-517.

References

谭锡斌.2012.龙门山推覆构造带新生代热演化历史研究及其对青藏高原东缘隆升机制的约束［D］:［学位论文］.北京: 中国地震局地质研究所.
TAN Xi-bin.2012.Cenozoic thermal history of the Longmenshan thrust belt: Implication for the uplift mechanism in the eastern margin of Tibetan plateau［D］.Ph D thesis. Institute of Geology, China Earthquake Administration, Beijing(in Chinese).
王卫民,郝金来,姚振兴.2013.2013年4月20日四川芦山地震震源破裂过程反演初步结果［J］.地球物理学报,56(4): 1412—1417.
WANG Wei-min,HAO Jin-lai,YAO Zhen-xing.2013.Preliminary result for rupture process of Apr.20,2013,Lushan earthquake,Sichuan,China［J］.Chines J Geophys,56(4): 1412—1417(in Chinese).
徐锡伟,韩竹军,李传友,等.2013.四川芦山7.0级强震: 一次典型的盲逆断层型地震［J］.科学通报,58: 1—1.
XU Xi-wei,HAN Zhu-jun,LI Chuan-you,et al.2013.Lushan M_S 7.0 earthquake: A blind reserve-fault earthquake［J］.Chin Sci Bull,58: 1—1(in Chinese).
Arne D,Worley B,Wilson C,et al.1997.Differential exhumation in response to episodic thrusting along the eastern margin of the Tibetan plateau［J］.Tectonophysics,280: 239—256.
Burchfiel B C.2004.2003 presidential address: New technology,new geological challenges［J］.GSA Today,14: 4—9.
Brandon M T.1996.Probability density plot for fission-track grain-age samples［J］.Nuclear Tracks and Radiation Measurements,26: 663—676.
Chen Z,Burchfiel B C,Liu Y,et al.2000.Global Positioning System measurements from eastern Tibet and their implications for India/Eurasia intercontinental deformation［J］.J Geophys Res,105: 16215—16227.doi: 10.1029/2000JB900092.
Cook K L,Royden L H,Burchfiel B C,et al.2013.Constraints on Cenozoic tectonics in the southwestern Longmen Shan from low-temperature thermochronology［J］.Lithosphere.doi: 10.1130/L263.1.
Gan W,Zhang P,Shen Z K,et al.2007.Present-day crustal motion within the Tibetan plateau［J］.J Geophys Res,112: B08416.doi: 10.1029/2005JB004120.
Godard V,Pik R,Lavé J,et al.2009.Late Cenozoic evolution of the central Longmen Shan,eastern Tibet: Insight from(U-Th)/He thermochronometry［J］.Tectonics,28.doi: 10.1029/2008TC002407.
Hubbard J,Shaw J H.2009.Uplift of the Longmen Shan and Tibetan plateau,and the 2008 Wenchuan(M_S 7.9)earthquake［J］.Nature,458(12): 194—197.
King R W,Shen F,Burchfiel B C,et al.1997.Geodetic measurements of crustal motion in southwest China［J］.Geology,25: 179—182.doi: 10.1130/0091—7613.
Kirby E,Reiners P W,Krol M A,et al.2002.Late Cenozoic evolution of the eastern margin of the Tibetan plateau: Inferences from ⁴⁰Ar/³⁹Ar and(U-Th)/He thermochronology［J］.Tectonics,21(1): 1—19.
Li Z,Liu S,Chen H,et al.2012.Spatial variation in Meso-Cenozoic exhumation history of the Longmen Shan thrust belt(eastern Tibetan plateau)and the adjacent western Sichuan basin: Constraints from fission track thermochronology［J］.Journal of Asian Earth Sciences,47: 185—203.
Liu T K,Hsieh S,Chen Y G,et al.2001.Thermo-kinematic evolution of the Taiwan oblique-collision mountain belt as revealed by zircon fission track dating［J］.Earth and Planetary Science Letters,186: 45—56.doi: 10.1016/S0012-821X(01)00232-1.
Meng Q R,Hu J M,Wang E,et al.2006.Late Cenozoic denudation by large-magnitude landslides in the eastern edge of Tibetan plateau［J］.Earth and Planetary Science Letters,243(1-2): 252—267.
Richardson N J,Densmore A L,Seward D,et al.2008.Extraordinary denudation in the Sichuan basin: Insights from low-temperature thermochronology adjacent to the eastern margin of the Tibetan plateau［J］.Journal of Geophysical Research,113: B04409.doi: 10.1029/2006JB004739.
Xu G,Kamp P J.2000.Tectonics and denudation adjacent to the Xianshuihe Fault,eastern Tibetan plateau: Constraints from fission track thermochronology［J］.J Geophys Res,105: 19231—19251.
Xu X W,Wen X Z,Yu G H,et al.2009.Coseismic reverse- and oblique-slip surface faulting generated by the 2008 Wenchuan M_W 7.9 earthquake,China［J］.Geology,37(6): 515—518.
Wang E,Kirby E,Furlong K P,et al.2012.Two-phase growth of high topography in eastern Tibet during the Cenozoic［J］.Nature Geoscience,5: 640—645.doi: 10.1038/ngeo1538.
Wilson C J L,Fowler A P.2011.Denudational response to surface uplift in east Tibet: Evidence from apatite fission-track thermochronology［J］.GSA Bulletin,123(9/10): 1966—1987.

[1]	LI Shu-yu, GAO Yuan, JIN Hong-lin, LIU Tong-zhen. CHARACTERISTICS OF UPPER CRUSTAL SHEAR WAVE SPLITTING IN THE NORTHEASTERN TIBETAN PLATEAU [J]. SEISMOLOGY AND GEOLOGY, 2024, 46(4): 916-933.
[2]	QIN Ke-xin, HU Gui-ming, LIU-ZENG Jing, SHEN Xu-wen, GAO Yun-peng, WANG Wen-xin, WEN Xin-yu, JIANG Shuai-yu. DEVELOPMENT AND PROSPECT OF THERMOLUMINESCENCE DATING BY USING CALCITE [J]. SEISMOLOGY AND GEOLOGY, 2024, 46(3): 699-722.
[3]	DAI Meng-yao, WANG Ping, LI An-bo, DING Lu, LIU Pin-qin, DAI Jin-gen, ZHANG Hui-ping, LIU Shao-feng. STATE OF ART AND PERSPECTIVE ON DATABASE CONSTRUCTION FOR LOW-TEMPERATURE THERMOCHRONOLOGY [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(6): 1432-1451.
[4]	CHEN Han-lin, WANG Qin-cai, ZHANG Jin-chuan, LIU Rui-feng. DISCUSSION ON SEISMOGENIC STRUCTURE OF THE JUNE 2022 M_S6.1 EARTHQUAKE AND ITS RELATIONSHIP WITH THE APRIL 2013 M_S7.0 EARTHQUAKE IN LUSHAN, SICHUAN PROVINCE [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(5): 1233-1246.
[5]	MA Si-yuan, XU Chong, CHEN Xiao-li. COMPARISON OF THE EFFECTS OF EARTHQUAKE-TRIGGERED LANDSLIDE EMERGENCY HAZARD ASSESSMENT MODELS: A CASE STUDY OF THE LUSHAN EARTHQUAKE WITH M_W5.8 ON JUNE 1, 2022 [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(4): 896-913.
[6]	LI Dan-dan, TANG Xin-gong, XIONG Zhi-tao. CRUSTAL DENSITY STRUCTURE OF THE EASTERN TIBETAN PLATEAU AND ITS GEODYNAMIC IMPLICATIONS [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(4): 936-951.
[7]	FU Ying, HU Bin, ZHAO Min, LONG Feng. PRECISE LOCATION AND SEISMOGENIC STRUCTURE OF THE 2022 LUSHAN M_S6.1 EARTHQUAKE [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(4): 987-1005.
[8]	ZHANG Wei-heng, CHEN Jie, LI Tao, DI Ning, YAO Yuan. LATE QUATERNARY SHORTENING RATE OF THE SANSUCHANG ANTICLINE, SOUTHERN LONGMEN SHAN FORELAND THRUST BELT [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(6): 1351-1364.
[9]	YE Yi-jia, TAN Xi-bin, QIAN Li. QUANTIFYING EROSION RATE AND ROCK ERODIBILITY FROM FLUVIAL SHEAR STRESS:AN EXAMPLE FROM LONGMEN SHAN [J]. SEISMOLOGY AND EGOLOGY, 2022, 44(1): 115-129.
[10]	TANG Mao-yun, LIU-ZENG Jing, LI Cui-ping, WANG Wei, ZHANG Jin-yu, XU Qiang. PROGRESS AND RESEARCH OF PALEOALTITUDE RECON-STRUCTION OF CENOZOIC BASINS IN THE SOUTHEASTERN TIBET PLATEAU [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(3): 576-599.
[11]	SONG Cheng-ke, ZHANG Hai-yang. ANALYSIS OF COSEISMIC VARIATIONS IN MAGNETIC FIELD OF THE LUSHAN M_S7.0 EARTHQUAKE IN 2013 [J]. SEISMOLOGY AND GEOLOGY, 2020, 42(6): 1301-1315.
[12]	LI Jia-yu, ZHENG Wen-jun, WANG Wei-tao, WAN Ying, ZHANG Pei-zhen, WANG Yang. THE NORTHWARD GROWTH OF THE NORTHEASTERN TIBETAN PLATEAU IN LATE CENOZOIC: IMPLICATIONS FROM APATITE (U-Th)/He AGES OF LONGSHOU SHAN [J]. SEISMOLOGY AND GEOLOGY, 2020, 42(2): 472-491.
[13]	WANG Zhen-nan, LU Ren-qi, XU Xi-wei, HE Deng-fa, CAI Ming-gang, LI Ying-qiang, LUO Jia-hong. THREE-DIMENSIONAL STRUCTURAL FEATURES OF THE PENGXIAN ACTIVE BLIND FAULT IN THE CENTRAL LONGMEN SHAN FRONT BELT [J]. SEISMOLOGY AND GEOLOGY, 2019, 41(4): 944-959.
[14]	WANG Hui, CAO Jian-ling, XU Hua-chao. PRELIMINARY APPLICATION OF FOCAL MECHANISM SOLUTIONS OF SMALL AND MEDIUM-SIZE EARTHQUAKES TO FAULT STABILITY ANALYSIS IN THE SOUTHEASTERN TIBETAN PLATEAU [J]. SEISMOLOGY AND GEOLOGY, 2019, 41(3): 633-648.
[15]	CHEN Zhao-hui, MENG Xiao-hong, ZHANG Shuang-xi, LIU Jin-zhao, WANG Tong-qing, ZHANG Pin, WEI Shao-gang. CHARACTERISTICS OF MULTI-SCALE GRAVITY FIELD VARIATION AND SEISMOGENIC MECHANISM ANALYSIS IN THE SOUTHEASTERN TIBETAN PLATEAU [J]. SEISMOLOGY AND GEOLOGY, 2019, 41(3): 690-703.