塑性流动网络控制下川滇菱形块体及邻区构造应力场与地震构造
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摘要
川滇地区位于中东亚塑性流动网络系统东南部 ,研究区内岩石圈下层含右向网带 6条和左向网带 16条 ,受其控制在多震层内形成相应的地震带。多震层和岩石圈下层的构造应力场在总趋势上基本一致 ,进一步证明了下层网状流动对上层的控制。沿网带以不同交角展布的发震断裂组成地震构造带 ,其中多数右向地震构造带已发育成熟 (视成熟度Λ≥ 0 .8) ,而左向带除大理 -通海和腾冲 -景洪两带接近成熟外 ,多数的Λ值显著小于 0 .8。“川滇菱形块体”因塑性流动网络的存在和块体边界的变迁 ,其现今构造和动力学涵义有待探讨。
The tectonic stress field and seismic tectonics in the Sichuan Yunnan rhombic block and its adjacent areas are investigated in terms of the "plastic flow network and multi layered tectonic deformation" model for continental dynamics (for short, called "netlike plastic flow" model or NPF model). According to the model, it is presented that in consideration of the transition of deformation regime from brittle to ductile with increasing depth, the lithosphere is divided into several tectonic deformation layers, i.e. the ductile lower lithosphere (including the lower crust and lithospheric mantle) with netlike plastic flow and the brittle upper lithosphere (including seismogenic layer and the shallow crust) with shear and tensile fractures, as well as the transitional layers (i.e. low velocity / high conductivity layers) discontinuously distributed between the two layers; the long range transmission of driving force applying at continental plate boundary is carried out mainly by the netlike plastic flow in the lower lithosphere, which controls intraplate tectonic stress field, tectonic deformation and seismic activities; the plastic flow network, which is composed of two families of plastic flow belts (i.e. ductile shear belts) intersecting each other, can be referred to as a "slip line" network developed under large deformation condition. The previous study indicates that the central eastern Asia plastic flow network system (CEAs) developed under the compression of the Himalayan driving boundary spreads over a broad area in central eastern Asia. The Sichuan Yunnan rhombic block is located in the southeastern part of CEAs and includes 6 right handed and 16 left handed plastic flow belts. Under the control of these plastic flow belts the large scale seismic belts and the seismotectonic zones consisting of seismic faults are formed within the overlying seismogenic layer. Most of the seismic faults in this region intersect the relevant seismotectonic zones at angles within the range of -15°～+30°, being longitudinal type faults. The directions of the maximum compressive stresses in the lower lithosphere can be estimated from the lines bisecting conjugate angles of the network. Comparing these directions with those in the seismogenic layer inferred using focal mechanism solutions, it is shown that both of them are identical with each other in general tendency, indicating that the stress field in the upper layer is controlled by that in the lower layer; meanwhile, the directions of the stress vectors in the seismogenic layer tend to deviate to some extent from the general tendency owing to the influences of local factors and estimation errors. The horizontal sliding angle of seismic faults (i.e. the angle included between the directions of the maximum compressive stress and the normal to fault strike) ranges from 36.0° to 78.5°, which are suitable for strike slip. Most of the right handed seismotectonic zones in this region have matured with the apparent maturities Λ ≥0.8 ( Λ is the ratio of the total length of the segments within seismic fault to that of the related seismic belt), while the Λ values of most of the left handed zones are considerably less than 0 8, called quasi seismotectonic zone, except the Dali Tonghai and Tengchong Jinghong zones which approach to maturing. It is worth noting that the previously active faults may transit to be quiescent, such as the southeastern segment of the Honghe Fault zone, since they deviate from the plastic flow belts, whereas the new seismotectonic zones may be developed along the plastic flow belts, such as the Dali Tonghai and Tengchong Jinghong seismotectonic zones. Thus, some boundaries of the rhombic block, such as the Honghe Fault zone, have been probably replaced by new boundaries associated with the plastic flow belts, and therefore the contemporary "Sichuan Yunnan rhombic block" can be considered as a tectonic unit defined by some plastic flow belts of CEAs as its boundaries.
The tectonic stress field and seismic tectonics in the Sichuan Yunnan rhombic block and its adjacent areas are investigated in terms of the "plastic flow network and multi layered tectonic deformation" model for continental dynamics (for short, called "netlike plastic flow" model or NPF model). According to the model, it is presented that in consideration of the transition of deformation regime from brittle to ductile with increasing depth, the lithosphere is divided into several tectonic deformation layers, i.e. the ductile lower lithosphere (including the lower crust and lithospheric mantle) with netlike plastic flow and the brittle upper lithosphere (including seismogenic layer and the shallow crust) with shear and tensile fractures, as well as the transitional layers (i.e. low velocity / high conductivity layers) discontinuously distributed between the two layers; the long range transmission of driving force applying at continental plate boundary is carried out mainly by the netlike plastic flow in the lower lithosphere, which controls intraplate tectonic stress field, tectonic deformation and seismic activities; the plastic flow network, which is composed of two families of plastic flow belts (i.e. ductile shear belts) intersecting each other, can be referred to as a "slip line" network developed under large deformation condition. The previous study indicates that the central eastern Asia plastic flow network system (CEAs) developed under the compression of the Himalayan driving boundary spreads over a broad area in central eastern Asia. The Sichuan Yunnan rhombic block is located in the southeastern part of CEAs and includes 6 right handed and 16 left handed plastic flow belts. Under the control of these plastic flow belts the large scale seismic belts and the seismotectonic zones consisting of seismic faults are formed within the overlying seismogenic layer. Most of the seismic faults in this region intersect the relevant seismotectonic zones at angles within the range of -15°～+30°, being longitudinal type faults. The directions of the maximum compressive stresses in the lower lithosphere can be estimated from the lines bisecting conjugate angles of the network. Comparing these directions with those in the seismogenic layer inferred using focal mechanism solutions, it is shown that both of them are identical with each other in general tendency, indicating that the stress field in the upper layer is controlled by that in the lower layer; meanwhile, the directions of the stress vectors in the seismogenic layer tend to deviate to some extent from the general tendency owing to the influences of local factors and estimation errors. The horizontal sliding angle of seismic faults (i.e. the angle included between the directions of the maximum compressive stress and the normal to fault strike) ranges from 36.0° to 78.5°, which are suitable for strike slip. Most of the right handed seismotectonic zones in this region have matured with the apparent maturities Λ ≥0.8 ( Λ is the ratio of the total length of the segments within seismic fault to that of the related seismic belt), while the Λ values of most of the left handed zones are considerably less than 0 8, called quasi seismotectonic zone, except the Dali Tonghai and Tengchong Jinghong zones which approach to maturing. It is worth noting that the previously active faults may transit to be quiescent, such as the southeastern segment of the Honghe Fault zone, since they deviate from the plastic flow belts, whereas the new seismotectonic zones may be developed along the plastic flow belts, such as the Dali Tonghai and Tengchong Jinghong seismotectonic zones. Thus, some boundaries of the rhombic block, such as the Honghe Fault zone, have been probably replaced by new boundaries associated with the plastic flow belts, and therefore the contemporary "Sichuan Yunnan rhombic block" can be considered as a tectonic unit defined by some plastic flow belts of CEAs as its boundaries.
引文
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DINGGuo yu,LIYong shan.1979.SeismicityandtherecentfracturingpatternoftheearthcrustinChina〔J〕.ActaGeologicaSinica,53(1):22—34(inChinese).
丁国瑜主编.1991.中国岩石圈动力学概论〔M〕.北京:地震出版社.
DINGGuo yu(chiefed).1991.LithosphericDynamicsofChina—ExplanatoryNotesfortheAtlasofLithosphericDynamicsofChina〔M〕.SeismologicalPress,Beijing(inChinese).
杜兴信,邵辉成.1999.由震源机制解反演中国大陆现代构造应力场〔J〕.地震学报,21(4):354—360.
DUXing xin,SHAOHui cheng.1999.ModerntectonicstressfieldintheChinesemainlandinversedfromfocal mechanismsolutions〔J〕.ActaGeophysicaSinica,21(4):354—360(inChinese).
国家地震局全国地震烈度区划编图组.1979.中国地震等烈度线图集〔Z〕.北京:地震出版社.
MappingGroupofSeismicIntensityZoninginChina,StateSeismologicalBureau.1979.AtlasofSeismicIntensityContoursofChina〔Z〕.SeismologicalPress,Beijing(inChinese).
何宏林,李,方仲景.1992.滇东南楔形构造区发震构造背景探讨〔J〕.地震地质,14(3):217—226.
HEHong lin,LIPing,FANGZhong jing.1992.AnalysisofseismogenicconditionsinthewedgetectonicregionofsoutheastYunnanProvince〔J〕.SeismologyandGeology,14(3):217—226(inChinese).
IGCP第206项中国工作组(丁国瑜主编).1989.中国活断层图集:全球主要活断层特性的对比(IGCP第206项)〔Z〕.北京:地震出版社,西安:西安地图出版社.
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LIPing(ed).1993.XianshuiheXiaojiangFaultZone〔M〕.SeismologicalPress,Beijing(inChinese).
马杏垣主编.1989.中国岩石圈动力学地图集〔Z〕.北京:中国地图出版社.
MAXing yuan(chiefed).1989.LithosphericDynamicsAtlasofChina〔Z〕.Beijing:ChinaCartographicPublishingHouse(inChinesewithEnglishsynopsesandcaptions).
宋方敏,汪一鹏,俞维贤,等.1998.小江活动断裂带〔M〕.北京:地震出版社.
SONGFang min,WANGYi peng,YUWei xian,etal.1998.TheActiveXiaojiangFaultZone〔M〕.Seismologi calPress,Beijing(inChinese).
王绳祖.1993.亚洲大陆岩石圈多层构造模型和塑性流动网络〔J〕.地质学报,67(1):1—18.
WANGSheng zu.1993.Multi layertectonicmodelforintraplatedeformationandplastic flownetworkintheAsiancontinentallithosphere〔J〕.ActaGeologicaSinica(Englishedition),6(3):247—271.
王绳祖,张四昌,田勤俭,等.2001.大陆动力学:网状塑性流动与多级构造变形〔M〕.北京:地震出版社.
WANGSheng zu,ZHANGSi chang,TIANQin jian,etal.2001.ContinentalDynamics:NetlikePlasticFlowandHirarchicalTectonicDeformation〔M〕.SeismologicalPress,Beijing(inChinesewithEnglishSummary).
王绳祖,张宗淳.1994.亚洲中东部“塑性流动-地震”网络系统及板内构造单元〔J〕.中国地震,10(3):238—250.
WANGSheng zu,ZHANGZong chun.1995.“Plastic flow/seismic”networksystemsandtectonicunitsincentral easternAsia〔J〕.EarthquakeResearchinChina(Englishedition),9(3):321—333.
王绳祖,张宗淳.1999.“塑性流动-地震”网络研究的新进展与中国大陆2000年度地震趋势的TP法预测.见:中国地震局地质研究所编.地震危险性预测研究(2000年度).北京:地震出版社.42—49.
WANGSheng zu,ZHANGZong chun.1999.Newprogressinstudyof”plastic flow/seismic”networksandthetendencyofseismicactivityinChinacontinentin2000 predictedusingtectonophysicalmethod〔A〕.In:Insti tuteofGeology,ChinaSeismologicalBureau(ed),ResearchonPredictionofSeismicRisk(2000).Seismologi calPress,Beijing.42—49(inChinese).
汪良谋.1982.康滇活动构造带的形成力学机制及其强震活动〔A〕.见:中国地质学会地震地质专业委员会编.中国活动断裂.北京:地震出版社.242—250.
WANGLiang mou.1982.ThemechanicalstudyofformationmechanismoftheKangdianactivetectoniczoneanditsintenseseismicity〔A〕.In:CommitteeonSeismogeology,TheSeismologicalSocietyofChina(ed).TheActiveFaultsinChina.SeismologicalPress,Beijing.242—250(inChinese).
向宏发,张晚霞,虢顺民,等.1998.滇西地区交切型断裂构造与现今地震活动时空分布〔A〕.见:中国地震局地质研究所编.地震危险性预测研究(1999年度).北京:地震出版社.100—109.
XIANGHong fa,ZHANGWan xia,GUOShun min,etal.1998.Cross typefaultstructuresandthetemporal spa tialdistributionofcontemporaryseismicactivityinthewesternYunnanregion〔A〕.In:InstituteofGeology,ChinaSeismologicalBureau(ed).ResearchonPredictionofSeismicRisk(1999).SeismologicalPress,Beijing.100—109(inChinese).
许忠淮,汪素云,黄雨蕊,等.1987.由多个小震推断的青甘和川滇地区地壳应力场的方向特征〔J〕.地球物理学报,30(5):476—486.
XUZhong huai,WANGSu yun,HUANGYu rui,etal.1987.DirectionsofmeanstressaxesinsouthwesternChi nadeducedfrommicroearthquakedata〔J〕.ActaGeophysicaSinica,30(5):476—486(inChinese).
张俊昌.1988.1970年通海地震断层的特征〔A〕.见:新疆维吾尔自治区地震局编.中国地震断层研究.乌鲁木齐:新疆人民出版社.72—79.
ZHANGJun chang.1988.Characteristicsofthe1970Tonghaiearthquakefault〔A〕.In:SeismologicalBureauofXinjiangUygurAutonomousRegion(ed).ResearchonSeismicFaultsinChina.XinjiangPeople’sPublishingHouse,Urumqi.72—79(inChinese).
周瑞琦,虢顺民,何蔚.1998.龙陵-澜沧断裂带双震型强震活动破裂模型讨论〔J〕.地震地质,20(3):261—268.
ZHOURui qi,GUOShun min,HEWei.1998.Astudyontherupturingmodelofthedouble mainshocksintheLonglinLancangfaultzone,Yunnan〔J〕.SeismologyandGeology,20(3):261—268(inChinese).
WANGSheng zu.1993.Net likeearthquakedistributionandplastic flownetworkincentralandeasternAsia〔J〕.PhysEarthPlanetInter,77:177—188.
XUJie,NiuLuan fang,WangChun hua,etal.1992.Basiccharacteristicsandresearchsignificanceoftheneo genicseismotectoniczone(NSZ)inChina〔A〕.In:Abstracts,2ndInt.Conf.onContinentalEarthquakes,1992,Beijing.240.
XUJie,HANZhu jun,WANGChun hua,etal.1996.Preliminarystudyontwonewly generatedseismotectoniczonesinNorthandSoutheastChina〔J〕.EarthquakeResearchinChina,10(4):393—402.
XUZhong huai,WANGSu yun,HUANGYu rui,etal.1989.China’stectonicstressfielddeducedfromearth quakes〔J〕.ActaGeophysicaSinica,32(4):509—520.
CUIXiao feng,XIEFu ren.1999.PreliminaryresearchtodeterminestressdistrictsfromfocalmechanismsolutioninSouthwestChinaanditsadjacentarea〔J〕.ActaSeismologicaSinica,21(5):513—522(inChinese).
丁国瑜,李永善.1979.我国地震活动与地壳现代破裂网络〔J〕.地质学报,53(1):22—34.
DINGGuo yu,LIYong shan.1979.SeismicityandtherecentfracturingpatternoftheearthcrustinChina〔J〕.ActaGeologicaSinica,53(1):22—34(inChinese).
丁国瑜主编.1991.中国岩石圈动力学概论〔M〕.北京:地震出版社.
DINGGuo yu(chiefed).1991.LithosphericDynamicsofChina—ExplanatoryNotesfortheAtlasofLithosphericDynamicsofChina〔M〕.SeismologicalPress,Beijing(inChinese).
杜兴信,邵辉成.1999.由震源机制解反演中国大陆现代构造应力场〔J〕.地震学报,21(4):354—360.
DUXing xin,SHAOHui cheng.1999.ModerntectonicstressfieldintheChinesemainlandinversedfromfocal mechanismsolutions〔J〕.ActaGeophysicaSinica,21(4):354—360(inChinese).
国家地震局全国地震烈度区划编图组.1979.中国地震等烈度线图集〔Z〕.北京:地震出版社.
MappingGroupofSeismicIntensityZoninginChina,StateSeismologicalBureau.1979.AtlasofSeismicIntensityContoursofChina〔Z〕.SeismologicalPress,Beijing(inChinese).
何宏林,李,方仲景.1992.滇东南楔形构造区发震构造背景探讨〔J〕.地震地质,14(3):217—226.
HEHong lin,LIPing,FANGZhong jing.1992.AnalysisofseismogenicconditionsinthewedgetectonicregionofsoutheastYunnanProvince〔J〕.SeismologyandGeology,14(3):217—226(inChinese).
IGCP第206项中国工作组(丁国瑜主编).1989.中国活断层图集:全球主要活断层特性的对比(IGCP第206项)〔Z〕.北京:地震出版社,西安:西安地图出版社.
ChineseWorkingGroupoftheProject206(Chiefed.DingGuo yu).1989.AtlasofActiveFaultsinChina〔Z〕.IGCPNo.206—WorldwideComparisonofCharacteristicsofMajorActiveFaults.SeismologicalPress,Beijing;Xi’anCartographicPublishingHouse,Xi’an(inChinese).
李主编.1993.鲜水河-小江断裂带〔M〕.北京:地震出版社.
LIPing(ed).1993.XianshuiheXiaojiangFaultZone〔M〕.SeismologicalPress,Beijing(inChinese).
马杏垣主编.1989.中国岩石圈动力学地图集〔Z〕.北京:中国地图出版社.
MAXing yuan(chiefed).1989.LithosphericDynamicsAtlasofChina〔Z〕.Beijing:ChinaCartographicPublishingHouse(inChinesewithEnglishsynopsesandcaptions).
宋方敏,汪一鹏,俞维贤,等.1998.小江活动断裂带〔M〕.北京:地震出版社.
SONGFang min,WANGYi peng,YUWei xian,etal.1998.TheActiveXiaojiangFaultZone〔M〕.Seismologi calPress,Beijing(inChinese).
王绳祖.1993.亚洲大陆岩石圈多层构造模型和塑性流动网络〔J〕.地质学报,67(1):1—18.
WANGSheng zu.1993.Multi layertectonicmodelforintraplatedeformationandplastic flownetworkintheAsiancontinentallithosphere〔J〕.ActaGeologicaSinica(Englishedition),6(3):247—271.
王绳祖,张四昌,田勤俭,等.2001.大陆动力学:网状塑性流动与多级构造变形〔M〕.北京:地震出版社.
WANGSheng zu,ZHANGSi chang,TIANQin jian,etal.2001.ContinentalDynamics:NetlikePlasticFlowandHirarchicalTectonicDeformation〔M〕.SeismologicalPress,Beijing(inChinesewithEnglishSummary).
王绳祖,张宗淳.1994.亚洲中东部“塑性流动-地震”网络系统及板内构造单元〔J〕.中国地震,10(3):238—250.
WANGSheng zu,ZHANGZong chun.1995.“Plastic flow/seismic”networksystemsandtectonicunitsincentral easternAsia〔J〕.EarthquakeResearchinChina(Englishedition),9(3):321—333.
王绳祖,张宗淳.1999.“塑性流动-地震”网络研究的新进展与中国大陆2000年度地震趋势的TP法预测.见:中国地震局地质研究所编.地震危险性预测研究(2000年度).北京:地震出版社.42—49.
WANGSheng zu,ZHANGZong chun.1999.Newprogressinstudyof”plastic flow/seismic”networksandthetendencyofseismicactivityinChinacontinentin2000 predictedusingtectonophysicalmethod〔A〕.In:Insti tuteofGeology,ChinaSeismologicalBureau(ed),ResearchonPredictionofSeismicRisk(2000).Seismologi calPress,Beijing.42—49(inChinese).
汪良谋.1982.康滇活动构造带的形成力学机制及其强震活动〔A〕.见:中国地质学会地震地质专业委员会编.中国活动断裂.北京:地震出版社.242—250.
WANGLiang mou.1982.ThemechanicalstudyofformationmechanismoftheKangdianactivetectoniczoneanditsintenseseismicity〔A〕.In:CommitteeonSeismogeology,TheSeismologicalSocietyofChina(ed).TheActiveFaultsinChina.SeismologicalPress,Beijing.242—250(inChinese).
向宏发,张晚霞,虢顺民,等.1998.滇西地区交切型断裂构造与现今地震活动时空分布〔A〕.见:中国地震局地质研究所编.地震危险性预测研究(1999年度).北京:地震出版社.100—109.
XIANGHong fa,ZHANGWan xia,GUOShun min,etal.1998.Cross typefaultstructuresandthetemporal spa tialdistributionofcontemporaryseismicactivityinthewesternYunnanregion〔A〕.In:InstituteofGeology,ChinaSeismologicalBureau(ed).ResearchonPredictionofSeismicRisk(1999).SeismologicalPress,Beijing.100—109(inChinese).
许忠淮,汪素云,黄雨蕊,等.1987.由多个小震推断的青甘和川滇地区地壳应力场的方向特征〔J〕.地球物理学报,30(5):476—486.
XUZhong huai,WANGSu yun,HUANGYu rui,etal.1987.DirectionsofmeanstressaxesinsouthwesternChi nadeducedfrommicroearthquakedata〔J〕.ActaGeophysicaSinica,30(5):476—486(inChinese).
张俊昌.1988.1970年通海地震断层的特征〔A〕.见:新疆维吾尔自治区地震局编.中国地震断层研究.乌鲁木齐:新疆人民出版社.72—79.
ZHANGJun chang.1988.Characteristicsofthe1970Tonghaiearthquakefault〔A〕.In:SeismologicalBureauofXinjiangUygurAutonomousRegion(ed).ResearchonSeismicFaultsinChina.XinjiangPeople’sPublishingHouse,Urumqi.72—79(inChinese).
周瑞琦,虢顺民,何蔚.1998.龙陵-澜沧断裂带双震型强震活动破裂模型讨论〔J〕.地震地质,20(3):261—268.
ZHOURui qi,GUOShun min,HEWei.1998.Astudyontherupturingmodelofthedouble mainshocksintheLonglinLancangfaultzone,Yunnan〔J〕.SeismologyandGeology,20(3):261—268(inChinese).
WANGSheng zu.1993.Net likeearthquakedistributionandplastic flownetworkincentralandeasternAsia〔J〕.PhysEarthPlanetInter,77:177—188.
XUJie,NiuLuan fang,WangChun hua,etal.1992.Basiccharacteristicsandresearchsignificanceoftheneo genicseismotectoniczone(NSZ)inChina〔A〕.In:Abstracts,2ndInt.Conf.onContinentalEarthquakes,1992,Beijing.240.
XUJie,HANZhu jun,WANGChun hua,etal.1996.Preliminarystudyontwonewly generatedseismotectoniczonesinNorthandSoutheastChina〔J〕.EarthquakeResearchinChina,10(4):393—402.
XUZhong huai,WANGSu yun,HUANGYu rui,etal.1989.China’stectonicstressfielddeducedfromearth quakes〔J〕.ActaGeophysicaSinica,32(4):509—520.
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