The Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt （CAOB）. The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfo...The Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt （CAOB）. The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfossils in the associated strata. Major and trace element data （including REE） for sandstones from the formation indicate that these rocks have a greywacke protolith and have been deposited during a strong tectonic activity. LA-ICPMS U-Pb dating of detrital zircons yield ages of 1801 to 238 Ma for four samples from the Linxi Formation. 425-585 Ma, together with the ~500 Ma age for the metamorphism event previously determined for Northeast China, indicates that their provenance is the metamorphic rocks of Pan-African age that have a tectonic affinity to NE China. A few older zircons with U-Pb ages at 1689-1801 Ma, 1307 1414 Ma, 593-978 Ma are also present, revealing the Neoproterozoic history of NE China. The youngest population shows a peak at ca. 252 Ma, suggesting that the main deposition of the Linxi Formation was at late Permain. Moreover, the ca. 250 Ma zircon grains of all four samples yield weighted mean ^206pb/^238U ages of 250 ± 3 Ma, 248 ± 3 Ma, 249 ± 3 Ma, and 250 ± 2 Ma, respectively. These ages, together with the youngest zircon age in the sample ZJB-28 （ca. 238 Ma）, suggest that the deposition of the Linxi Formation extended to the early Triassic. Combining with previous results, we suggest that the final collision of the Central Asian Orogenic Belt （CAOB） in the southern of Linxi Formation, which located in the Solonker-Xra Moron-Changchun suture, and the timing for final collision should be at early Triassic.展开更多
本文对定义北半球平流层春季最后增温事件(Stratospheric Final Warming,SFW)爆发日期的三种不同方法进行了比较分析。三种方法分别为:1)基于平流层极夜急流核心纬度带(60°--75°N)逐日纬向平均纬向风最后一次由西风转为东风...本文对定义北半球平流层春季最后增温事件(Stratospheric Final Warming,SFW)爆发日期的三种不同方法进行了比较分析。三种方法分别为:1)基于平流层极夜急流核心纬度带(60°--75°N)逐日纬向平均纬向风最后一次由西风转为东风的时间,简称为逐日风场反转法;2)将月平均纬向风场数据线性插值成逐日数据,然后基于插值后的逐日纬向平均纬向风由西风转为东风的时间,简称为月均风场插值法;3)90°N与60°N之间纬向平均温度经向梯度最后一次由负转正的日期,简称为温度梯度反转法。结果表明,由逐日风场反转法和月均风场插值法得到的SFW爆发日期基本一致,但是当平流层冬末和春初发生爆发性增温时,两种方法确定的SFW爆发日期易出现较大偏差;温度梯度反转法确定的SFW爆发日期早于逐日风场反转法确定的SFW爆发日期,在30 hPa等压面层,两种方法定义的平均日期相差16 d。由于逐日风场反转法在实际使用时更为常见,因此,以该方法为参考,对温度梯度反转法进行修订,结果表明,如果将温度梯度反转法中的阈值由0 K提高为3 K,以上利用温度和风场确定的SFW爆发日期则基本一致。展开更多
Recently, because of the importance of research into environmental change and thanks to the overlap of some branches of sciences, there has been great advance in dendrochronology. The response of ring-width growth to ...Recently, because of the importance of research into environmental change and thanks to the overlap of some branches of sciences, there has been great advance in dendrochronology. The response of ring-width growth to variation of ecological en- vironment system has become one of the major projects in earth science and ecology.展开更多
基金funded by grants from the Chinese Ministry of Science and Technology(Grant No.2013CB429802)National Natural Science Foundation of China(Grant Nos.41390441,41190075, and 41272241)the Chinese Geological Survey(Grant No. 1212011120153)
文摘The Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt （CAOB）. The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfossils in the associated strata. Major and trace element data （including REE） for sandstones from the formation indicate that these rocks have a greywacke protolith and have been deposited during a strong tectonic activity. LA-ICPMS U-Pb dating of detrital zircons yield ages of 1801 to 238 Ma for four samples from the Linxi Formation. 425-585 Ma, together with the ~500 Ma age for the metamorphism event previously determined for Northeast China, indicates that their provenance is the metamorphic rocks of Pan-African age that have a tectonic affinity to NE China. A few older zircons with U-Pb ages at 1689-1801 Ma, 1307 1414 Ma, 593-978 Ma are also present, revealing the Neoproterozoic history of NE China. The youngest population shows a peak at ca. 252 Ma, suggesting that the main deposition of the Linxi Formation was at late Permain. Moreover, the ca. 250 Ma zircon grains of all four samples yield weighted mean ^206pb/^238U ages of 250 ± 3 Ma, 248 ± 3 Ma, 249 ± 3 Ma, and 250 ± 2 Ma, respectively. These ages, together with the youngest zircon age in the sample ZJB-28 （ca. 238 Ma）, suggest that the deposition of the Linxi Formation extended to the early Triassic. Combining with previous results, we suggest that the final collision of the Central Asian Orogenic Belt （CAOB） in the southern of Linxi Formation, which located in the Solonker-Xra Moron-Changchun suture, and the timing for final collision should be at early Triassic.
基金Project supported by the National Natural Science Foundation of China
文摘Recently, because of the importance of research into environmental change and thanks to the overlap of some branches of sciences, there has been great advance in dendrochronology. The response of ring-width growth to variation of ecological en- vironment system has become one of the major projects in earth science and ecology.
