Search

The 2008 Wenchuan earthquake and associated co-seismic landslide was the most recent expression of the rapid deformation and erosion occurring in the eastern Tibetan Plateau. The erosion associated with co-seismic landslides balances the long-term tectonic uplift in the topographic evolution of the region; however, the quantitative relationship between earthquakes, uplift, and erosion is still unknown. In order to quantitatively distinguish the seismically-induced erosion in the total erosion, here, we quantify the Wenchuan earthquake-induced erosion using the digital elevation model (DEM) differential method and previously-reported landslide volumes. Our results show that the seismically-induced erosion is comparable with the pre-earthquake short-term erosion. The seismically-induced erosion rate contributes ~50% of the total erosion rate, which suggests that the local topographic evolution of the middle Longmen Shan region may be closely related to tectonic events, such as the 2008 Wenchuan earthquake. We propose that seismically-induced erosion is a very important component of the total erosion, particularly in active orogenic regions. Our results demonstrate that the remote sensing technique of differential DEM provides a powerful tool for evaluating the volume of co-seismic landslides produced in intermountain regions by strong earthquakes.

The expansion of Asian inland aridification not only resulting in the desert and Gobi development in the mid-high latitudes of the northern hemisphere, but also become the main source of the global aeolian dust, which even today profoundly affect billions of people. Consequently, understanding the origination, development and expansion history of those aeolian deposits have been a hot research topic around the world, which could provide essential information for assessing future regional and global trends of climate and environmental conditions and social-economic activities organizing in this area. However, previous studies were mainly focus on central Asia; the Northeast China as the eastmost Eurasia boundary of the aeolian dust transportation and expansion, has been rarely studied. The loess-paleosol sequences, as the typical surface aeolian deposit in late Cenozoic, have been confirmed as the classic recording archives of the Asian aridification history and contain a direct indicator of past atmospheric circulation. Especially, the loess-paleosol accumulation located at the sand-desert downwind area, has an excellent coupling relationship with the formation and evolution of Asian aridification expansion, which can well constrain the evolution process of Asian aridification expansion. Songnen Plain is located at the easternmost Eurasian arid-semi-arid zone, which is the final inland area for aeolian dust accumulation, and is sensitive to the climate fluctuations and could provide the earliest timing record of the Asian aridification eastward-expansion. After late Quaternary mammal fossils and paleolithic investigations at the 1970s, the systematic lithostratigraphic division studies of the Songnen plain are started from 1980s. Based on the magnetostratigraphy, 14C and OSL dating results, combined with excavation of Mammuthus primigenius Blumenbach and Coelodonta antiquitatis Blumenbach, Sun et al. (1982) and Wu et al. (1984) divided the stratum of Songnen plain into Huangshan formation (early Pleistocene), Dongfeng formation (middle Pleistocene), Harbin formation (late Pleistocene), and Tantu formation (Holocene) from bottom to top, respectively. However, because of the unknown of exactly location at which the fossils were found, the stratigraphic division of Songnen plain remains debate. In this study, we present an iconic ~55 sediment section (including ~29.9m loess-paleosol sequences) deposited at north Songnen Plain, Northeast China. On the basis of magnetostratigraphy, the chronostratigraphy of the 14C, OSL and ESR dating were performed on this section, which could provide a better absolute dating constrain on the evolution history of the Asian aridification expansion and climate change. [ABSTRACT FROM AUTHOR]

Carbonates, precipitated by either biogenic or chemical processes, emit luminescence signals under both thermal and optical stimulations [1,2,3]. Although these signals are promising for dating, the case studies are still sparse, which poses difficulties in targeting appropriate material for dating, with respect to the great generic diversity of carbonates. Developed geothermal activities of Western Sichuan Plateau (WSP) facilitate the formation of various carbonates closed to the fault fissures, e.g., banded carbonates along the fault surface, domed carbonates near hot springs, travertine deposits as well as carbonate dominated detrital. Besides these morphological diversity, the mineralogy and geochemical signatures of these carbonates are also different, e.g., calcite, aragonite and dolomite. Carbonate luminescence dating would allow us to constrain the tectonic activity across temporal scales of four orders of magnitude (103-106 years) with no potential systematic bias. In this study, we collected carbonate rocks and detrital from WSP to systematically investigate their luminescence characteristics and evaluate their suitability for dating accordingly. Thermoluminescence (TL and Isothermal TL in UV, blue and UV to yellow), blue light stimulated luminescence (BLSL in UV), infrared stimulated luminescence (IRSL in UV and blue) and radiofluorescence (RL in IR) signals of the aforementioned samples are measured. The kinetics of corresponding trapped electrons are constrained under sunlight bleaching, laboratory heating and laboratory storage to evaluate their optical bleachability, thermal and athermal stabilities for dating. We tentatively relate the observed diverse characteristics of these luminescence signals to the mineralogy and geochemical context of the samples. The mineral composition, crystallization index, trace and main elements concentration of these samples will be analyzed to characterize the samples in mineralogy space. Finally, the luminescence characteristics and the mineralogy features will be compared to identify the best-possible mineral for luminescence dating. [ABSTRACT FROM AUTHOR]

We used airborne light detection and ranging (LiDAR) data to reevaluate the singleevent offsets of the 1920 Haiyuan Ms 8.5 earthquake and the cumulative offsets along the western and middle segments of the coseismic surface rupture zone. Our LiDAR data indicate that the offset observations along both the western and middle segments fall into groups. The group with the minimum slip amount is associated with the 1920 Haiyuan Ms 8.5 earthquake, which ruptured both the western and middle segments. Our research highlights two new interpretations: First, the previously reported maximum displacement of the 1920 earthquake was likely due to at least two earthquakes; second, our results reveal that the cumulative offset probability density (COPD) peaks of the same offset amounts on the western and middle segments do not correspond to one another one-to-one. We suggest that any discussion of the rupture pattern of a certain fault based on the offset data should also consider fault segmentation and paleoseismological data. Therefore, the COPD peaks should be computed and analyzed on fault subsections and not entire fault zones to study the number of paleoearthquakes and their rupture patterns. [ABSTRACT FROM AUTHOR]