CAJ | 학술논문

断层陡坎崩积楔是断层活动的直接产物,是古地震事件的重要证据.对于崩积楔的准确定年是解决古地震事件的关键.近几年得益于释光技术与方法的发展,简单多片再生法(SMAR)已成功应用于130 ka以来黄土类型沉积物的定年.以山西忻定盆地五台山北麓南峪口探槽为例,对该探槽中的两期崩积楔(D1、D2)各个部位不同类型沉积物进行系统采样,对样品采用细颗粒石英(4～11 μm)简单多片再生法(SMAR)进行光释光(OSL)测年,根据光释光年龄,得出如下认识:(1)D1、D2崩积楔演化过程与常规的正断层崩积楔演化模式有些差别;(2)D1崩积楔古地形面由断层处向外延伸堆积而成,D2崩积楔古地形面由水平堆积形成,且较D1厚;(3)D1崩塌结束后经历较强的水流作用;(4)两次古地震事件分别发生于(42.77±2.46)～(61.72±2.82) ka、(32.80±2.87)～(47.92±0.94) ka,时间间隔为10～15 ka.
단층두감붕적설시단층활동적직접산물,시고지진사건적중요증거.대우붕적설적준학정년시해결고지진사건적관건.근궤년득익우석광기술여방법적발전,간단다편재생법(SMAR)이성공응용우130 ka이래황토류형침적물적정년.이산서흔정분지오태산북록남욕구탐조위례,대해탐조중적량기붕적설(D1、D2)각개부위불동류형침적물진행계통채양,대양품채용세과립석영(4～11 μm)간단다편재생법(SMAR)진행광석광(OSL)측년,근거광석광년령,득출여하인식:(1)D1、D2붕적설연화과정여상규적정단층붕적설연화모식유사차별;(2)D1붕적설고지형면유단층처향외연신퇴적이성,D2붕적설고지형면유수평퇴적형성,차교D1후;(3)D1붕탑결속후경력교강적수류작용;(4)량차고지진사건분별발생우(42.77±2.46)～(61.72±2.82) ka、(32.80±2.87)～(47.92±0.94) ka,시간간격위10～15 ka.
The fault scrap collapse wedge is the direct result of fault activity, it is also signification of paleoearthquake events, its accurate dating is the key to solve the problems about paleoearthquake events.Luminescence techniques are rapidly progressing in recent years.Simplified multiple aliquot regenerative-dose (SMAR) protocol is already applied successfully in loessial sediments after 130 ka.The studied samples are collected detailedly in two fault scarp collapse wedges(D1 and D2) from the schematic section of Nanyukou in north piedmont zone of Wutai Mountain in Xinding basin, Shanxi Province.The sample ages are acquired with fine grain quartz (4-11 μm) SMAR protocol.The results of the OSL dating show that evolutional models of D1 and D2 are different from general model of normal fault collapse wedge.The palaeotopography of D1 is formed by accumulating nearby the fault to stretch out far, whereas the palaeotopography of D2 is formed by accumulating horizontally and is thicker than D1.After dilapidation powerful current has rised in D1. The results indicate that the older paleoearthquake event occurred between (42.77±2.46) ka and (61.72±2.82) ka, the younger paleoearthquake event occurred between (32.80±2.87) ka and (47.92±0.94) ka.The interval of the two paleoearthquake events is between 10 ka and 15 ka.