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931.
932.
农用地自然质量等级划分是农用地分等的前提和基础,其划分合理与否直接关系到农用地分等能否川页利进行,但现有研究方法难以全面反映农用地自然质量的差异性及其性质的可变性。依据浙江省的地形地貌等自然条件差异,将其划分为六大区域,并选择性地构建了不同的农用地自然质量等级划分的因素指标(基础肥力、土壤质地、有机质、耕层厚度、灌溉、排涝、pH、地下水位、坡度等)和评分标准,在此基础上基于可拓理论建立了农用地自然质量等级划分的可拓评价模型,并运用模型对水稻、小麦和油菜作物分别进行可拓评价及多作物综合分等,最终得到浙江省农用地自然质量分等结果。研究表明,可拓评价方法能反映农用地自然质量等级的动态性和可变性,使评价更为精细化和客观化,结果更符合浙江省农用地实际情况。 相似文献
933.
934.
References: 《东北亚地学研究》2007,10(1):110-112
This study utilizes ANSYS to establish FEM's model of metamorphic core complex, and used thermal-structure analysis to simulate metamorphic core complex's temperature field and stress field. The meta- morphic core complex formation mechanism is discussed. The simulation results show that the temperature field change appearing as the earth surface' s temperature is the lowest, and the temperature of metamorphic core complex' s nucleus is the highest. The temperature field is higher along with depth increase, and the stress field change appearing as the biggest stress occurs in the nucleus. The next stress field occurs at the top of the cover. 相似文献
935.
FENG Yipeng WANG Genhou WANG Shulai LI Dian WANG Huan LU Yang LIU Han ZHANG Peilie 《《地质学报》英文版》2024,98(1):32-49
The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural-lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro- and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast. The presence of various deformation features and quartz C-axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (?) ranging from 9.77×10?14 s?1 to 6.52×10?16 s?1. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar-39Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike-slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene. 相似文献
936.
翁泉沟硼铁矿床赋存于早元古宙辽河群里尔峪组。原岩为一套在裂谷环境下形成的中酸性火山岩及碳酸盐岩。矿体的容矿岩石是镁质大理岩。矿体厚度与容矿岩石厚度呈正相关关系。矿石矿物有硼镁石、硼镁铁矿、遂安石等,伴生矿物达64种。根据矿石所含的矿物种类,翁泉沟硼铁矿床矿石类型可分为磁铁矿型、硼镁石型、硼镁石—磁铁矿型、含硼镁铁矿—硼镁石—磁铁矿型等4种类型。硼镁铁矿是在火山喷气和深海沉积作用下形成的层控火山沉积变质矿床。 相似文献
937.
C. E. JACOBSON 《Journal of Metamorphic Geology》1995,13(1):79-92
Abstract The Rand and Pelona Schists consist of eugeoclinal rock types overlain by continental basement along the Vincent-Chocolate Mountains (VCM) faults. Both schists display inverted metamorphic zonation, defined in part by a systematic variation in composition of calcic to sodic-calcic amphibole in mafic schist structurally upward. The compositional progressions include increase of total A1, A1IV and Ti, but decrease in the ratios of Na/(Na + Ca) to A1/(A1 + Si), and NaM4 to (A1VI + Fe3+ + Ti). These variations imply that structurally high rocks belong to a lower-pressure metamorphic fades series than those at depth. This result is consistent with previous views that the inverted metamorphic zonations represent intact structural sequences.
Amphibole composition is dependent not only on structural position (i.e. P-T ), but also upon bulk-rock composition. The important controls are whole-rock Mg/(Mg + Fe2+ + Mn) and Fe3+ /Fe2+ . The greatest impact of these factors, however, is on the absolute values of Na and Al, rather than their ratio. Thus, interpretation of facies series is not seriously hindered by compositional variability.
Sodic amphibole in epidote blueschists from the Rand Schist is extensively replaced by sodic-calcic amphibole. Sodic-calcic amphibole in the Rand Schist and Pelona Schist is, itself, rimmed by actinolitic amphibole. Similar blueschist to greenschist transitions in other metamorphic terranes are typically attributed to exhumation. In the Rand and Pelona Schists, the sequence probably formed during burial. 相似文献
Amphibole composition is dependent not only on structural position (i.e. P-T ), but also upon bulk-rock composition. The important controls are whole-rock Mg/(Mg + Fe
Sodic amphibole in epidote blueschists from the Rand Schist is extensively replaced by sodic-calcic amphibole. Sodic-calcic amphibole in the Rand Schist and Pelona Schist is, itself, rimmed by actinolitic amphibole. Similar blueschist to greenschist transitions in other metamorphic terranes are typically attributed to exhumation. In the Rand and Pelona Schists, the sequence probably formed during burial. 相似文献
938.
超高压变质岩中微粒金刚石的发现及其动力学意义 总被引:1,自引:0,他引:1
概述了目前仅有的几个发现微粒金刚石的地区如哈萨克斯坦,挪威西部和我国中等部地的超高压变质岩的最新研究成果,并指出这些变质岩中微粒金刚石为变质成因,变质流体对微粒金刚石的形成具有十分重要的意义。 相似文献
939.
利用国家气象站和区域自动气象站的降水观测资料以及暴雨洪涝灾害情况资料,分析了2007—2019年大连地区暴雨气候特征时空分布,并进行了灾害评估和敏感区域识别。结果表明:1) 大连地区年平均暴雨和大暴雨日数在空间分布上东北部多于西南部,大暴雨出现的概率为0—40%。年平均暴雨量和大暴雨量的极大值区域主要集中于庄河地区,年均暴雨强度也呈现从西到东逐渐递增趋势。暴雨变异系数的高值中心出现在瓦房店西部地区,低值区出现在庄河地区。2) 大连市的暴雨灾害近80%为较严重灾害,最严重和严重暴雨灾害各占9%—10%。3) 普兰店西南部、庄河西部与大连市区为大连地区暴雨洪涝灾害相对敏感区域。 相似文献
940.