断裂带尾端扩展变形与连接方式是认识断裂带生长和连接机制的关键。大凉山断裂从北向南由雁列状排列的公益海断层等6条断层组成,构成鲜水河与小江左行走滑断裂间的转换连接断裂。因此,位于最北端的公益海断层是理解鲜水河断裂尾端扩展变...断裂带尾端扩展变形与连接方式是认识断裂带生长和连接机制的关键。大凉山断裂从北向南由雁列状排列的公益海断层等6条断层组成,构成鲜水河与小江左行走滑断裂间的转换连接断裂。因此,位于最北端的公益海断层是理解鲜水河断裂尾端扩展变形,并进而分析大凉山连接断裂形成的关键。然而,由于对公益海断层的应变性质和强度缺少有效约束,导致对断裂扩展和连接机制认识的分歧。我们对公益海断层进行了详细的地质调查和构造解析,并对变形岩石的磁化率各向异性(anisotropy of magnetic susceptibility,AMS)进行了分析。结果表明:1)公益海断层的活动分为两阶段:D_(1)阶段以逆冲作用为主,兼具右行走滑分量,D_(2)阶段以左行走滑作用为主,兼具逆冲分量;2)磁化率各向异性分析显示,公益海断层两盘岩石以顺磁性矿物为主导(K_(m)=36~1330μSI);磁化率椭球呈现两期变形特征:D_(1)期为NNE—NE向缩短,特征值(P_(j)—T)显示应变强度自断层北、中和南段中部向两端递增;D_(2)期为NW向缩短,指示应变集中分布于断层尾端;3)基于前人年代学研究成果,本文提出新的构造演化模型:在鲜水河和小江断裂尾端共同作用下,D_(1)期形成多个具有逆冲性质的韧-脆性剪切带,以左列或者右列形式组合并沿剪切带向两端扩展;D_(2)期各韧-脆性剪切带以左行走滑作用为主并逐渐完成连接形成大凉山断裂,进一步则向鲜水河—大凉山—小江断裂系的完全贯通发展。展开更多
The Almus Fault Zone(AFZ)is one of the major splay faults of the North Anatolian Fault Zone(NAFZ)and is important for understanding its tectonic features and assessing regional seismic hazards.This research presents t...The Almus Fault Zone(AFZ)is one of the major splay faults of the North Anatolian Fault Zone(NAFZ)and is important for understanding its tectonic features and assessing regional seismic hazards.This research presents the integration of morphometric indices to quantitatively assess the spatial variation of tectonic activity along the AFZ.The AFZ is an active fault with both strike-slip and normal fault components and consists of two main branches,Mercimekdağı-Çamdere Fault(MÇF)and Tokat Fault(TF)segments.This study aims to assess the relative tectonic activity of the AFZ using various morphometric indices,based on a 10 m resolution DEM,with the aid of ArcGIS and MATLAB software.For this purpose,morphometric indices such as hypsometric integral(HI:0.35-0.65),mountain front sinuosity(Smf:1.3-1.44),valley floor width-height ratio(Vf:0.15-2.28),asymmetry factor(AF:23-77),drainage basin shape(Bs:1.13-6.10)and normalized steepness index(ksn:1-498)were applied to 53 drainage basins.When the Smf and mean Vf indices results were evaluated,it was calculated that the uplift ratio of the region was more than 0.5 mm/yr.The spatial distribution of the relative tectonic activity(Iat)of the area was revealed by combining the obtained morphometric indices analysis results.According to the Iat result,it was concluded that the MercimekdağıÇamdere Fault and Tokat Fault segments have high tectonic activity,but the Mercimekdağı-Çamdere Fault segment has higher tectonic activity.The results obtained were also confirmed by field observations.This research provides valuable information for the evaluation of tectonic activity in drainage systems controlled by splay faults.展开更多
文摘断裂带尾端扩展变形与连接方式是认识断裂带生长和连接机制的关键。大凉山断裂从北向南由雁列状排列的公益海断层等6条断层组成,构成鲜水河与小江左行走滑断裂间的转换连接断裂。因此,位于最北端的公益海断层是理解鲜水河断裂尾端扩展变形,并进而分析大凉山连接断裂形成的关键。然而,由于对公益海断层的应变性质和强度缺少有效约束,导致对断裂扩展和连接机制认识的分歧。我们对公益海断层进行了详细的地质调查和构造解析,并对变形岩石的磁化率各向异性(anisotropy of magnetic susceptibility,AMS)进行了分析。结果表明:1)公益海断层的活动分为两阶段:D_(1)阶段以逆冲作用为主,兼具右行走滑分量,D_(2)阶段以左行走滑作用为主,兼具逆冲分量;2)磁化率各向异性分析显示,公益海断层两盘岩石以顺磁性矿物为主导(K_(m)=36~1330μSI);磁化率椭球呈现两期变形特征:D_(1)期为NNE—NE向缩短,特征值(P_(j)—T)显示应变强度自断层北、中和南段中部向两端递增;D_(2)期为NW向缩短,指示应变集中分布于断层尾端;3)基于前人年代学研究成果,本文提出新的构造演化模型:在鲜水河和小江断裂尾端共同作用下,D_(1)期形成多个具有逆冲性质的韧-脆性剪切带,以左列或者右列形式组合并沿剪切带向两端扩展;D_(2)期各韧-脆性剪切带以左行走滑作用为主并逐渐完成连接形成大凉山断裂,进一步则向鲜水河—大凉山—小江断裂系的完全贯通发展。
文摘The Almus Fault Zone(AFZ)is one of the major splay faults of the North Anatolian Fault Zone(NAFZ)and is important for understanding its tectonic features and assessing regional seismic hazards.This research presents the integration of morphometric indices to quantitatively assess the spatial variation of tectonic activity along the AFZ.The AFZ is an active fault with both strike-slip and normal fault components and consists of two main branches,Mercimekdağı-Çamdere Fault(MÇF)and Tokat Fault(TF)segments.This study aims to assess the relative tectonic activity of the AFZ using various morphometric indices,based on a 10 m resolution DEM,with the aid of ArcGIS and MATLAB software.For this purpose,morphometric indices such as hypsometric integral(HI:0.35-0.65),mountain front sinuosity(Smf:1.3-1.44),valley floor width-height ratio(Vf:0.15-2.28),asymmetry factor(AF:23-77),drainage basin shape(Bs:1.13-6.10)and normalized steepness index(ksn:1-498)were applied to 53 drainage basins.When the Smf and mean Vf indices results were evaluated,it was calculated that the uplift ratio of the region was more than 0.5 mm/yr.The spatial distribution of the relative tectonic activity(Iat)of the area was revealed by combining the obtained morphometric indices analysis results.According to the Iat result,it was concluded that the MercimekdağıÇamdere Fault and Tokat Fault segments have high tectonic activity,but the Mercimekdağı-Çamdere Fault segment has higher tectonic activity.The results obtained were also confirmed by field observations.This research provides valuable information for the evaluation of tectonic activity in drainage systems controlled by splay faults.
