Qash Qooly valley runs parallel to Pera Magroon, Sara and Surdash anticlines, almost in SE-NW trend, and merges with the Lesser Zab River 9 km southeast to Dokan town. Before its development, it was a large basin with...Qash Qooly valley runs parallel to Pera Magroon, Sara and Surdash anticlines, almost in SE-NW trend, and merges with the Lesser Zab River 9 km southeast to Dokan town. Before its development, it was a large basin with width ranges between 2-3 km, which was filled during Pleistocene or may be Late Pliocene by different types of sediments. The presence of the calcrete on the top indicates a wet period that has lasted for a long time as indicated from the thickness of the calcrete and alluvial fan sediments. The age of Qash Qooly valley was estimated using the exposure age determination method. The type of the sediments, their thicknesses, and erosion intensity and sediments' dens dissection by rills were the main features used. This study concluded that the age of the basin is Pliocene--Late Pleistocene, whereas the valley started to be developed during uppermost Late Pleistocene and is still active in shifting its course.展开更多
The need to standardise stratigraphical subdivisions of continuous marine sedimentary successions that outcrop for hundreds metres, using clearly defined points fixed in the field is strongly felt. A proposal is prese...The need to standardise stratigraphical subdivisions of continuous marine sedimentary successions that outcrop for hundreds metres, using clearly defined points fixed in the field is strongly felt. A proposal is presented here to formalize regional stages for the Lower Pleistocene (Calabrian) and for the Middle Pleistocene (Ionian) in Italy. The sections are well exposed, carefully investigated using multiple criteria (an integrated stratigraphical approach) and located in the central part of the Mediterranean. This area is recognized worldwide as a classical region for the Neogene and the Pleistocene sequences. The terrestrial record is directly correlated with the deep-sea record, as determined from ODP Sites 653 (Tyrrhenian Sea), 963 (Sicily Channel) and 964 (Ionian Sea)from the central Mediterranean. The present formal proposal is consistent with the INQUA and ICS decision to define and correlate the Plio/Pleistocene boundary (GSSP at Vrica) within the Olduvai Subchron, at 1.81 My, the Lower/Middle Pleistocene boundary at the Matuyama/Brunhes reversal at 0. 78 My and the Middle/ Upper Pleistocene boundary with the base of MIS 5, approximately 0. 13My. The present proposal also is consistent with the call for stage unit stratotypes that emphasize both the physical content of a stage and its boundaries (Hilgen et al., 2006).展开更多
In this study, we analyzed the spatiotemporal variation of cold surges in Inner Mongolia between 1960 and 2012 and their possible driving factors using daily minimum temperature data from 121 meteorological stations i...In this study, we analyzed the spatiotemporal variation of cold surges in Inner Mongolia between 1960 and 2012 and their possible driving factors using daily minimum temperature data from 121 meteorological stations in Inner Mongolia and the surrounding areas. These data were analyzed utilizing a piecewise regression model, a Sen+Mann- Kendall model, and a correlation analysis. Results demonstrated that (1) the frequency of single-station cold surges decreased in Inner Mongolia during the study period, with a linear tendency of -0.5 times/10a (-2.4 to 1.2 times/10a). Prior to 1991, a significant decreasing trend of-1.1 times/10a (-3.3 to 2.5 times/10a) was detected, while an increasing trend of 0.45 times/10a (-4.4 to 4.2 times/10a) was found after 1991. On a seasonal scale, the trend in spring cold surges was consistent with annual values, and the most obvious change in cold surges occurred during spring. Monthly cold surge frequency displayed a bimodal structure, and November witnessed the highest incidence of cold surge. (2) Spatially, the high incidence of cold surge is mainly observed in the northern and central parts of Inner Mongolia, with a higher occurrence observed in the northern than in the central part. Inter-decadal character- istic also revealed that high frequency and low frequency regions presented decreasing and increasing trends, respectively, between 1960 and 1990. High frequency regions expanded after the 1990s, and regions exhibiting high cold surge frequency were mainly distributed in Tulihe, Xiao'ergou, and Xi Ujimqin Banner. (3) On an annual scale, the cold surge was dominated by AO, NAO, CA, APVII, and CQ. However, seasonal differences in the driving forces of cold surges were detected. Winter cold surges were significantly correlated with AO, NAO, SHI, CA, TPI, APVII, CW, and IZ, indicating they were caused by multiple factors. Au- tumn cold surges were mainly affected by CA and IM, while spring cold surges were significantly correlated with CA and APVII.展开更多
The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selectedfor studying the environmental conditions surrounding the transitio...The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selectedfor studying the environmental conditions surrounding the transition between Paleolithic foragers and Neolithic farmer/pastoral- ists. Short cores were obtained from four lake basins in the southwestern Tengger using a hand-driven piston coring device. Proxies from these cores were supplemented by ra- diocarbon ages obtained from lake sediment cores, shoreline features and spring mound deposits. Together these records provide evidence of millennial-scale climate change events from the Pleistocene-Holocene transition to the present. Lake/wetland events, representing periods of more intensive summer monsoon, occur in the records at ~12.7-11.6, ~10.1, ~9.3, ~8.0, ~5.4, ~1.5, and ~0.8 ka BP. They do suggest that century- to millennial-scale climatic cycles are characteristic of the Holocene in the southeastern Tengger Desert although the chronology must be considered extremely tentative.展开更多
文摘Qash Qooly valley runs parallel to Pera Magroon, Sara and Surdash anticlines, almost in SE-NW trend, and merges with the Lesser Zab River 9 km southeast to Dokan town. Before its development, it was a large basin with width ranges between 2-3 km, which was filled during Pleistocene or may be Late Pliocene by different types of sediments. The presence of the calcrete on the top indicates a wet period that has lasted for a long time as indicated from the thickness of the calcrete and alluvial fan sediments. The age of Qash Qooly valley was estimated using the exposure age determination method. The type of the sediments, their thicknesses, and erosion intensity and sediments' dens dissection by rills were the main features used. This study concluded that the age of the basin is Pliocene--Late Pleistocene, whereas the valley started to be developed during uppermost Late Pleistocene and is still active in shifting its course.
文摘The need to standardise stratigraphical subdivisions of continuous marine sedimentary successions that outcrop for hundreds metres, using clearly defined points fixed in the field is strongly felt. A proposal is presented here to formalize regional stages for the Lower Pleistocene (Calabrian) and for the Middle Pleistocene (Ionian) in Italy. The sections are well exposed, carefully investigated using multiple criteria (an integrated stratigraphical approach) and located in the central part of the Mediterranean. This area is recognized worldwide as a classical region for the Neogene and the Pleistocene sequences. The terrestrial record is directly correlated with the deep-sea record, as determined from ODP Sites 653 (Tyrrhenian Sea), 963 (Sicily Channel) and 964 (Ionian Sea)from the central Mediterranean. The present formal proposal is consistent with the INQUA and ICS decision to define and correlate the Plio/Pleistocene boundary (GSSP at Vrica) within the Olduvai Subchron, at 1.81 My, the Lower/Middle Pleistocene boundary at the Matuyama/Brunhes reversal at 0. 78 My and the Middle/ Upper Pleistocene boundary with the base of MIS 5, approximately 0. 13My. The present proposal also is consistent with the call for stage unit stratotypes that emphasize both the physical content of a stage and its boundaries (Hilgen et al., 2006).
基金Major Project of High-resolution Earth Observation System
文摘In this study, we analyzed the spatiotemporal variation of cold surges in Inner Mongolia between 1960 and 2012 and their possible driving factors using daily minimum temperature data from 121 meteorological stations in Inner Mongolia and the surrounding areas. These data were analyzed utilizing a piecewise regression model, a Sen+Mann- Kendall model, and a correlation analysis. Results demonstrated that (1) the frequency of single-station cold surges decreased in Inner Mongolia during the study period, with a linear tendency of -0.5 times/10a (-2.4 to 1.2 times/10a). Prior to 1991, a significant decreasing trend of-1.1 times/10a (-3.3 to 2.5 times/10a) was detected, while an increasing trend of 0.45 times/10a (-4.4 to 4.2 times/10a) was found after 1991. On a seasonal scale, the trend in spring cold surges was consistent with annual values, and the most obvious change in cold surges occurred during spring. Monthly cold surge frequency displayed a bimodal structure, and November witnessed the highest incidence of cold surge. (2) Spatially, the high incidence of cold surge is mainly observed in the northern and central parts of Inner Mongolia, with a higher occurrence observed in the northern than in the central part. Inter-decadal character- istic also revealed that high frequency and low frequency regions presented decreasing and increasing trends, respectively, between 1960 and 1990. High frequency regions expanded after the 1990s, and regions exhibiting high cold surge frequency were mainly distributed in Tulihe, Xiao'ergou, and Xi Ujimqin Banner. (3) On an annual scale, the cold surge was dominated by AO, NAO, CA, APVII, and CQ. However, seasonal differences in the driving forces of cold surges were detected. Winter cold surges were significantly correlated with AO, NAO, SHI, CA, TPI, APVII, CW, and IZ, indicating they were caused by multiple factors. Au- tumn cold surges were mainly affected by CA and IM, while spring cold surges were significantly correlated with CA and APVII.
基金supported by US NSF(Grant Nos.9410923 and 9729929)National Natural Science Foundation of China(Grant No.40125001).
文摘The area along the eastern and southeastern margins of the Tengger Desert, NW China, which is sensitive to the summer monsoon variations, was selectedfor studying the environmental conditions surrounding the transition between Paleolithic foragers and Neolithic farmer/pastoral- ists. Short cores were obtained from four lake basins in the southwestern Tengger using a hand-driven piston coring device. Proxies from these cores were supplemented by ra- diocarbon ages obtained from lake sediment cores, shoreline features and spring mound deposits. Together these records provide evidence of millennial-scale climate change events from the Pleistocene-Holocene transition to the present. Lake/wetland events, representing periods of more intensive summer monsoon, occur in the records at ~12.7-11.6, ~10.1, ~9.3, ~8.0, ~5.4, ~1.5, and ~0.8 ka BP. They do suggest that century- to millennial-scale climatic cycles are characteristic of the Holocene in the southeastern Tengger Desert although the chronology must be considered extremely tentative.