Although its origin has not yet reached a consensus so far, MTS （Molar-Tooth Structure） has been documented for more than 100 years. Current study reports a discovery of MTS from the Mesoproterozoic Wumishan Formati...Although its origin has not yet reached a consensus so far, MTS （Molar-Tooth Structure） has been documented for more than 100 years. Current study reports a discovery of MTS from the Mesoproterozoic Wumishan Formation, Lingyuan, Yanshan Region, North China, and the features and geological implications of MTS are further discussed. Here, straitigraphic horizons of MTS＇s occurrences show that it was mainly located within the top part of the Wumishan Formation, i.e., limestone unit. Four kinds of morphology of MTS, i.e., fine fusiform, debris, ribbon, ptigmatic and nodular （irregular）, were recognized and thought to be highly related to the sedimentary environments and facies. Geochemistry of MTS including oxides, trace elements and C, O and Sr isotopes indicates that the horizons of MTS-bearing is of higher Sr/Ba and Ca/Mg ratios, lower positive ~13C and highly negative 3180 values than the adjacent stratigraphic levels of rare MTS. Lithology, morphology and geochemistry of MTS in the Wumishan Formation suggest that MTS occurs mainly in shallow subtidal near the storm wave base, which is typically characterized by warm temperature, oversaturated calcium carbonate seawater and high organic productivity. Furthermore, occasional enrichment of algae bacteria here is more favorable for the calcification of calcium oozes and catalytic for MTS. C isotope composition of the Wumishan Formation and MTS of this study is well correlated with that of the Mesoproterozoic Belt Supergroup, North America and Riphean, Siberia, suggesting that MTS acts as a sedimentary record responding to global changes and is a perfect indicator in Precambrian stratigraphic correlation worldwide.展开更多
In Lingyuan region of West Liaoning Province, the Zhangjiakou Formation (J_3z) and the Yixian Formation (K_1y) display an angular unconformity. That is, the Lower Mesozoic strata of the Zhangjiakou Formation are ENE (...In Lingyuan region of West Liaoning Province, the Zhangjiakou Formation (J_3z) and the Yixian Formation (K_1y) display an angular unconformity. That is, the Lower Mesozoic strata of the Zhangjiakou Formation are ENE (near E-W) oriented, while the overlying strata of the Yixian Formation exhibit an NNE orientation. The results of LA-ICP-MS zircon U-Pb ages show the Zhangjiakou Formation formed from about 130 Ma to 132 Ma in Lingyuan and 135 Ma to 136 Ma in Luanping (North Hebei Province), respectively. Three conclusions can be drawn: (1) The Zhangjiakou Formation in Lingyuan is comparable to that in Luanping, with the volcanic rocks of the Zhangjiakou Formation from Lingyuan being younger than those from Luanping. (2) 5-6 Ma difference between the top of the Zhangjiakou Formation and the bottom of the Yixian Formation in Lingyuan proves the angular unconformity between the two formations; and it reflects that the 5-6 Ma interval period is the main period of the transition of tectonic framework in Mesozoic in North Hebei and West Liaoning. In the interval period, the magmatic action went up to high tide in Mesozoic in the northeast of China. Moreover, after the interval period, the “Rehe fauna” developed into “erupted” period. This reflects that the interval period is also an important biological interface in Northern Hebei and Western Liaoning. (3) The Dabeigou Formation in Luanping should correspond to the upper part of the Zhangjiakou Formation, but not to the lower part of the Yixian Formation.展开更多
以农用地分等成果为基础进行耕地评价与立地条件分析研究,在土地评价领域推进农用地分等成果转化应用。该文以辽宁省凌源市为例,充分利用农用地分等成果,借鉴美国LESA(land evaluation and site assessment)思想,对研究区分别进行耕地...以农用地分等成果为基础进行耕地评价与立地条件分析研究,在土地评价领域推进农用地分等成果转化应用。该文以辽宁省凌源市为例,充分利用农用地分等成果,借鉴美国LESA(land evaluation and site assessment)思想,对研究区分别进行耕地质量评价和立地条件分析,并建立凌源市耕地质量评价与立地条件分析体系。该体系评价结果将凌源市耕地分为8级,其中1和2级耕地属于自然质量条件和立地条件较优的耕地,3～5级耕地属于自然质量条件尚可,受立地条件影响差异较大的耕地,7和8级耕地属于自然质量条件较差,无任何立地条件优势的耕地。以农用地分等成果为基础建立土地评价与立地条件分析体系是切实可行的,同时在该体系中要因地制宜的选取耕地立地条件因素。展开更多
基金supported by the National Natural Science Foundation(No.40772078)the marineoil and gases exploration progress project of SINOPIC'Petroleum Geology Research and Oil Potential Prospect of the Precambrian stratigraphy of the North China Platform(No.GB0800-06-ZS-350)Foundation of Geology Institute of CAGS(No.J0903,No.J1106)
文摘Although its origin has not yet reached a consensus so far, MTS （Molar-Tooth Structure） has been documented for more than 100 years. Current study reports a discovery of MTS from the Mesoproterozoic Wumishan Formation, Lingyuan, Yanshan Region, North China, and the features and geological implications of MTS are further discussed. Here, straitigraphic horizons of MTS＇s occurrences show that it was mainly located within the top part of the Wumishan Formation, i.e., limestone unit. Four kinds of morphology of MTS, i.e., fine fusiform, debris, ribbon, ptigmatic and nodular （irregular）, were recognized and thought to be highly related to the sedimentary environments and facies. Geochemistry of MTS including oxides, trace elements and C, O and Sr isotopes indicates that the horizons of MTS-bearing is of higher Sr/Ba and Ca/Mg ratios, lower positive ~13C and highly negative 3180 values than the adjacent stratigraphic levels of rare MTS. Lithology, morphology and geochemistry of MTS in the Wumishan Formation suggest that MTS occurs mainly in shallow subtidal near the storm wave base, which is typically characterized by warm temperature, oversaturated calcium carbonate seawater and high organic productivity. Furthermore, occasional enrichment of algae bacteria here is more favorable for the calcification of calcium oozes and catalytic for MTS. C isotope composition of the Wumishan Formation and MTS of this study is well correlated with that of the Mesoproterozoic Belt Supergroup, North America and Riphean, Siberia, suggesting that MTS acts as a sedimentary record responding to global changes and is a perfect indicator in Precambrian stratigraphic correlation worldwide.
文摘In Lingyuan region of West Liaoning Province, the Zhangjiakou Formation (J_3z) and the Yixian Formation (K_1y) display an angular unconformity. That is, the Lower Mesozoic strata of the Zhangjiakou Formation are ENE (near E-W) oriented, while the overlying strata of the Yixian Formation exhibit an NNE orientation. The results of LA-ICP-MS zircon U-Pb ages show the Zhangjiakou Formation formed from about 130 Ma to 132 Ma in Lingyuan and 135 Ma to 136 Ma in Luanping (North Hebei Province), respectively. Three conclusions can be drawn: (1) The Zhangjiakou Formation in Lingyuan is comparable to that in Luanping, with the volcanic rocks of the Zhangjiakou Formation from Lingyuan being younger than those from Luanping. (2) 5-6 Ma difference between the top of the Zhangjiakou Formation and the bottom of the Yixian Formation in Lingyuan proves the angular unconformity between the two formations; and it reflects that the 5-6 Ma interval period is the main period of the transition of tectonic framework in Mesozoic in North Hebei and West Liaoning. In the interval period, the magmatic action went up to high tide in Mesozoic in the northeast of China. Moreover, after the interval period, the “Rehe fauna” developed into “erupted” period. This reflects that the interval period is also an important biological interface in Northern Hebei and Western Liaoning. (3) The Dabeigou Formation in Luanping should correspond to the upper part of the Zhangjiakou Formation, but not to the lower part of the Yixian Formation.
文摘以农用地分等成果为基础进行耕地评价与立地条件分析研究,在土地评价领域推进农用地分等成果转化应用。该文以辽宁省凌源市为例,充分利用农用地分等成果,借鉴美国LESA(land evaluation and site assessment)思想,对研究区分别进行耕地质量评价和立地条件分析,并建立凌源市耕地质量评价与立地条件分析体系。该体系评价结果将凌源市耕地分为8级,其中1和2级耕地属于自然质量条件和立地条件较优的耕地,3～5级耕地属于自然质量条件尚可,受立地条件影响差异较大的耕地,7和8级耕地属于自然质量条件较差,无任何立地条件优势的耕地。以农用地分等成果为基础建立土地评价与立地条件分析体系是切实可行的,同时在该体系中要因地制宜的选取耕地立地条件因素。
