The wedge-shaped deposit formed in front of fault scarp is called colluvial wedge. Repeated faulting by faults may produce multiple colluvial wedges, each of which represents a paleoseismic event. When there are two or more colluvial wedges, the new colluvial wedge is in sedimentary contact with the fault, while the old ones are in fault contact with the fault. The shape of colluvial wedge is usually in the form of horizontal triangle, and the sedimentary facies is usually of binary structure. The overall grain size decreases gradually from bottom to top. Soil layer generally develops on the top, and different types of soil are developed under different climate or soil environments. Another deposit in front of fault scarp is the sag pond graben. The graben in front of sag pond is generally a set of sedimentary assemblages of colluvial facies, alluvial diluvial facies and swamp facies. The area close to the fault, especially the main fault, is of colluvial facies, while the area away from the fault is of alluvial and pluvial facies and marshy facies. In an accumulative cycle, the size of the deposit decreases from bottom to top, and soil layers develop on the top or surface. Multiple pile-ups may be a marker for identifying multiple faulting events. The pile-up strata such as colluvial wedge and fault sag pond can be used as identification markers for paleoseismic events. Colluvial wedge and sag pond, as the identification markers for paleoearthquake, have been well applied to practical research. However, there is still lack of detailed research on the lithological structure and genetic evolution in the interior of colluvial wedge and sag pond sediment, meanwhile, there is still a deficiency in the analysis of the completeness and the regional characteristics of paleoearthquake by using colluvial wedge and sag pond sediment. This paper discusses the method of identifying paleoearthquake by using sag pond sediments and colluvial wedge. We discuss the lithologic combination and sedimentary evolution of sag pond and choose the surface rupture zone of the 1679 M8.0 earthquake on the Xiadian Fault as the research area. In this paper, the distribution range and filling sequence of sag pond are analyzed, using borehole exploration. Four paleoearthquake events are identified since 25ka to 12ka, based on the sag pond sediments and colluvial wedge. The in situ recurrence interval of these seismic events is 480a, 510a, 7 630a and 2 830a, respectively. The lithologic combination and sedimentary evolution law of the sag pond sediments caused by an ancient earthquake are discussed. The sag pond distribution range and filling sequence are determined by the surface elevation survey and drilling exploration. The exploratory trench exposes the sag pond filling strata sequence and lithologic combination. Based on this, we analyze the three sedimentation stages of sag pond sediments formed by a paleoearthquake event near the earthquake fault. It is believed that the filling sequence is composed from bottom to top of the colluvial wedge, the erosion surface or unconformity surface, the fine detrital sediments(containing biological debris)and paleosols. For the fault-sag ponds formed by active faults, the paleoearthquakes occurred near the unconformity or erosion surface of the sediments of the fault-plug ponds. An ancient earthquake event includes the combination of organic deposits such as sediments, clastic deposits, bioclasts, burrow, plant roots and other organic deposits on the vertical scour surface or unconformity. The time interval between two paleoseismic events is defined by two adjacent unconformities(or scour surfaces). According to the vertical facies association and chronological test results of the sediments in the Pangezhuang trough of the Xiatan Fault, four paleo-seismic events are identified since the late Pleistocene period of 25~12ka BP, with recurrence intervals of 480a, 510a, 7 630a and 2 830a, respectively.

Because of the frequent seismic activity in Songyuan in recent years, the modes of tectonic movement in this area since the Quaternary have attracted increasing consideration. This paper selects the Gudian Fault which locates between the southeast uplift and central depression of Songliao Basin as the research object. We discussed the Quaternary structural characteristics of the Gudian Fault using growth strata. Using the data of deep seismic reflection prospecting for oil, we determined the location, geometry and kinematics characteristics of the Gudian Fault. And using the shallow seismic reflection prospecting data, the combined drilling exploration data and TL data, we determined precisely the inversion tectonics feature of the fault since late Cenozoic. Based on the above data, we believe that the Gudian Fault is dominated mainly by thrust-folding since Quaternary. A set of growth strata is recognized by shallow seismic reflection exploration data. According to the overlap of growth strata and the relationship between deposition rate and uplift rate, we confirm that the uplift rate of Gudian Fault in the early of Early Pleistocene is less than 0.15mm/a. And according to the offlap of growth strata and the relationship between deposition rate and uplift rate, the uplift rate of the Gudian Fault is more than 0.091mm/a in the late of Early Pleistocene and more than 0.052mm/a in middle Pleistocene. According to the chronological data, it is determined that the uplift rate of the Gudian Fault is 0.046mm/y since 205ka.

The Tashkurgan-Yarkant River,which is the upper reach of the Tarim River,originates from the Karakoram Mountains in the west syntaxis of the Tibetan Plateau.Thick terrace sediments are widespread along the Tashkurgan-Yarkant River.These deposits contain geologic fingerprints that allow identification of the environmental changes and geologic hazards.However,few geochronological data was available on these sedimentations to allow us to build an irreproachable age model.4 samples of fine grains from one terrace profile were dated by optically stimulated luminescence(OSL)dating method.In darkroom,fractions of fine grains(4～11μm)were extracted from the bulk samples.OSL signal measurements were performed on an automated Daybreak system.Identical D_e plateau in the thermal treat was observed in preheat plateau test.Tests of luminescence characteristics confirm the suitability of the material for OSL dating.Our results indicate the deposition age for these sediments is between 4.3～7.3ka.After the river terrace deposited,the river has deeply incised for 27±5m,with the incision rate 6.3±1.2mm/a.The thermochronologic data show that the magnitude of exhumation decreases from upstream(west)to downstream(east)along the Tashkurgan-Yarkand River.These data may reflect the the active uplift process of Mustagh Ata antiform.

In historical records,no earthquake of magnitude comparable with that of the Wenchuan M_S 8.0 earthquake has ever been reported in Chengdu and Longmenshan regions.The penultimate event similar to the 12 May 2008 M_S 8.0 was revealed by the surface ruptures in the vicinity of Xiaoyudong.It is important,therefore,to date accurately when the prior large earthquake happened.This paper presents 7 optically stimulated luminescence(OSL)ages from Xiaoyudong trench.We investigate the use of simplified multiple aliquot regenerative-dose(SMAR)protocol and single aliquot regenerative-dose(SAR)protocol from fine-grain quartz to date deposits associated with earthquake.The results of SMAR and SAR protocols are consistent.The behavior of quartz to different internal consistency checks of SAR protocol(preheat plateau,thermal transfer,recycling ratio,recuperation and growth curves)and of SMAR protocol(dose recovery)used for the dose estimation method was satisfactory.Various internal consistency tests of the measurement protocols indicate that the dose estimates from the fine grain quartz are accurate and the optical ages are reliable.The preliminary OSL ages indicate that the last large earthquake happened between 1.7～2.2ka and the slip rate of Xiaoyudong Fault was 1.0±0.08mm/a at least in Holocene.

The fluvial terrace has plenty of paleoclimate and paleoenviromental information which play an important role in paleoclimate and paleoenviromental researches.In this paper,we drilled a 42.85m-long core(N06S2)in 2007,which was located in the south bank of Yangtze River at Shifuqiao in Qixia district of Nanjing City.Firstly,fine quartz grains(4～11μm)were extracted from bulk samples in dark room,and the quartz purity tests were conducted.The results show that purity can satisfy the experiment.All measurements were performed on an automated Daybreak 2200 TL/OSL system with blue(470±5nm)light stimulation and U-340 luminescence detection filters.Thick source alpha counting(TSAC)was used to measure the uranium and thorium concentrations.The potassium content was determined using flame spectrophotometer.Secondly,the preheat plateau test and dose recovery test were performed on one sample using the SAR protocol.The results indicate that the fast component dominates the OSL signals.In preheat plateau test,identical D_e in the thermal treat from 160～260℃ was observed,thus we use the preheat temperature of 220℃ for 10 seconds.The recuperation ratios of zero point are below 2％and the recycling ratios lie between 0.9 and 1.1.In dose recovery test,OSL signal sensitivity changes are well corrected.Tests of luminescence characteristics confirm the suitability of the material for OSL dating.At last,samples from this drilling core were systematically dated by optically stimulated luminescence(OSL)dating method,and samples which contain organic matters were dated by AMS¹⁴ C.The results show that the D_e values from the two methods accord with each other very well.However,OSL dating results show that there is a hiatus in this core,and the hiatus,which ranges from 1.9ka to 7.9ka,may be the result of change of Yangtze River's channel or the erosion of the river.The ages of the fluvial deposition mainly range from 0.26ka to 1.9ka and 7.9ka to 9.1ka,it could be attributed to the results of paleoclimate and sea levels change.Meanwhile,study results on pollen and spores show that the paleoclimate has changed from warm wet to temperate wet during the stage of hiatus.

Some water-lain sediments samples with different ages were selected from several regions in China,and their Standardized Growth Curves(SGC)were constructed for fine-grained quartz OSL signals that were measured by sensitivity-corrected multiple aliquot regenerative-dose protocol(SMAR).The equivalent dose of each sample can be determined by plotting their standard OSL intensity((L_N/T_N)*T_D)into the SGC curve.To estimate the reliability of this method in water lain sediments,their SGC E_D values were compared to that of SMAR E_D using their own individual growth curve.It is found that the uncertainty is up to 19% for natural samples with E_D values of 12～65Gy.For the E_D values greater than 65Gy,their uncertainty is much larger.While for samples with E_D values of less than 12Gy,the maximum uncertainty is up to 25%.Using the information of E_D values estimated by SGC protocol,we can easily and accurately obtain regeneration doses for SMAR protocol and further obtain the E_D value for each sample.This will save much time in dating application.

The fine-grain quartz extracted from two burnt reworked loess samples LEDL0588H and LEDL0365 was measured by modified SAR and SMAR protocols for OSL dating.The fast component is dominant in OSL signals.The identical De in the thermal treatment from 180～260℃was showed in preheat plateau test using both protocols.As was shown in measuring the values T_X/T_N and L_N/L_N as a function of preheat temperatures,in dose recovery test in SAR and the value of L_N/L_N in SAR and SMAR protocols,OSL signal sensitivity changes were well corrected.Both methods can be used to estimate De of the two samples properly for OSL dating.Although located at different strata levels,the similar OSL ages of two samples suggest the latest time they were burnt may be at a same period of human activity.

Optical dating of fine-grained fluvial sediments remains a complex endeavour. Five fluvial sediments have been collected from the Kalanggouluke He,Mingyaole anticline,in the Southwestern Tian Shan. We employ both ‘Double-SAR' and ‘Double-SMAR' procedure in which aliquots are subjected to both infrared (λ=860nm) and blue (λ=470nm) stimulation and two sets of De determinations are produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively. There are significant differences between the equivalent doses for the IRSL and (post-IR) OSL measurements. We extracted fine-grained quartz via etching in fluorosilicic acid for sample LEDL03-87q,LEDL03-86q and LEDL04-54q. SMAR procedure (Wang et al.,2005) and SAR procedure were used to determine their equivalent dose (De). Our data indicate a significant IRSL De underestimate due to anomalous fading of the natural IRSL from feldspathic fine grains for all the samples. Caution should be taken when using the post-IR OSL De for fluvial sediments. BLSL De distribution analysis indicates that samples LEDL03-87q,LEDL03-86q and LEDL04-54q were partially bleached. We suggest using the minimum component of De to estimate their ages.

The preservation of multiple,clearly deformed Late Quaternary fluvial terraces and nearly continuous exposure of underlying Neogene sediments make the Mingyaole anticline detachment fold system particularly favorable for unraveling the geomorphic and structural history of underlying fold growth within the southwestern Chinese Tian Shan Foreland Basin. We mapped the Neogene structure and Pleistocene terrace surfaces along the south-flowing Kalanggouluke He within water gap across the anticline using 1∶50000 scale stereo air photographs and topographic maps. The anticline has steep (58°～70°) limbs and is box-like,characterized by broad north vergent core that rises above gently dipping outer flanks,suggestive of detachment folding. Since the growth strata are not sufficiently exposed to allow us to discern the kinematic style of fold growth,we profiled all sets of progressively deformed Pleistocene fluvial terraces plus the present rivers across the of the anticline using a laser ranging theodolite (total station) aiming to use the terrace flights as kinematic markers for the recent evolution of the folds. The terrace profiles are preserved across the steeply dipping cores and show several common features: (1) Where long profiles of terraces could be surveyed,the terraces show increased tilts with age. (2) The greatest tilts are preserved in the north limb towards the core of the fold. (3) Nearly all of the observed terrace heights are attributable to differential uplift. (4) The pre-growth strata and the terrace treads are discordant everywhere. (5) Part of the terraces are not folded across previously active axial surfaces that are now passive,and younger axial surfaces that remain active as evidenced by fold scarps. In combination with structural data,growth strata,and deformed terraces,we infer that the width of the Mingyale anticline is established early and is subsequently amplified throughout the history of the fold,but not in a purely self-similar style. Continued shortening is accommodated by vertical growth of the fold via a combination of limb rotation in the center and hinge migration on the flanks. Planar,rotated terraces indicate more recent folding is accommodated by block rotation of the limbs. In combination with paleomagnetic study and OSL dating,we infer the fold growth initiated ~1.6Ma and shortening rate and differential uplift rate decreased since then. Uplift is always greater than shortening which indicates limb rotation dominates.

Fluvial terraces,like growth strata,provide geomorphic markers that can record progressive deformation and mechanisms on underlying fault-related folds. Because terraces are generally preserved within the pre-growth strata,they record the deformation mechanism in the core of the fold. To explore the fold evolution and subsequent geometry of deformed terraces,we present ideal kinematic models for successively emplaced horizontal unconformities (terraces) across pre-growth strata in three types of growing fault-related fold. Three common mechanisms for fold growth are considered: hinge migration (Limb-lengthening),limb rotation,and a combination of the two. Both angular-hinge and curved-hinge zone migration are considered. Each model predicts distinct terrace architecture,fold scarps,and different angular relationships between the terraces and the pre-growth strata.Limb-lengthening fault-bend fold results in self-similar growth,marked by parallel pre-growth and terrace strath orientations across much of the fold,and steeply dipping asymmetric fold scarps along the fold's flanks.Limb-lengthening fault-propagation fold models result in self-similar growth parallel terraces,and step fold scarps in the back limb. Deformation by limb rotation detachment fold is marked by progressively less tilted terraces across the limbs and symmetric fold scarps along the fold's flanks.Migration of an angular hinge of detachment fold results in parallel,uplifted terraces in the core and steeply dipping symmetric fold scarps along the fold's flanks. When limb rotation and hinge migration are combined,the terrace architecture is consistent with the kinematics of each kink panel.The result of limb lengthening by migration of a curved hinge is dependent on the width of the curved hinge.If the hinge is wide and terrace abandonment is frequent compared to the migration rate,fanning terraces and fold scarps result. In additional,changes in base level have significant effects on the final terrace geometry. Uniform incision along the river profile results in an apparent uplift of the older terraces,while aggradation will cause older terraces to truncate into the less tilted,younger terraces.