Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divide...Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divided in terms of their peak temperature of metamorphism. Medi-um-temperature eclogites (MT), as Group B, occur in the Dabie Group. They were formedfrom epidote-amphibolite facies. The metamorphism of eclogite facies has two stages: the co-esite eclogite facies stage (the peak condition: T = 600-700℃, P = 2. 7 - 3. 0 GPa) and theglaucophane eclogite facies stage (the pressure decreases, may be lower than 2. 5 GPa while thetemperature has little change). Low temperature eclogites (LT), as Group C, occur in the Qi-jiaoshan Formation. They were formed from blue schist facies (the peak condition: T = 490 -560℃, P< 1. 5 GPa). The appearance of hydrous minerals in the eclogites indicates the im-portant role of water in metamorphism. Medium-temperature eclogites are different from low-temperature ones in metamorphism. At last, the evolution of the high-pressure metamorphicbelt is discussed as well.展开更多
厘清耕地演变的驱动机制对中国耕地资源可持续利用具有重要现实意义。该研究以鄂南地区为例,利用2000-2005、2005-2010和2010-2015年3期Landsat遥感影像解译成果、15类POI(Point of Interest)空间数据等,采用主成分分析、多元Logistic...厘清耕地演变的驱动机制对中国耕地资源可持续利用具有重要现实意义。该研究以鄂南地区为例,利用2000-2005、2005-2010和2010-2015年3期Landsat遥感影像解译成果、15类POI(Point of Interest)空间数据等,采用主成分分析、多元Logistic回归模型、边际效应分析等方法,系统分析了研究区近15 a以来耕地动态变化及其时空演变规律,并着重探讨了空间要素在驱动机制方面的双向边际效应。结果表明:1)耕地演变类型在空间上表现出相同类型的集聚性,转换类型受周边同类用地空间溢出效应影响明显。在时间上表现出不同转换类型的差异性,转换类型受土地利用政策宏观调控影响向建设用地单一转化趋势明显。2000-2015年间,耕地向建设用地的转换比例自28%过渡至44%后,迅速上升至96%,主要集中在城镇周边、主要道路沿线等区域。2)空间要素对不同时期耕地不同转化类型存在不同的边际效应,2000-2015年间耕地不同转化类型的边际效应变化幅度逐渐减小、不同转化类型边际效应曲线同类交点呈同向移动趋势。自然区位因素对耕地向建设用地转换和耕地向水域转换在POI空间要素不同取值时边际效应的变化较明显。3)空间要素边际效应曲线特征揭示其影响存在临界性,在临界值范围内,边际效应随着空间要素取值不同变化明显,但在临界值范围外,边际效应趋于稳定。耕地演变空间要素边际效应的定性定量分析对耕地布局优化与区域协调发展策略制定具有良好参考作用。展开更多
文摘Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divided in terms of their peak temperature of metamorphism. Medi-um-temperature eclogites (MT), as Group B, occur in the Dabie Group. They were formedfrom epidote-amphibolite facies. The metamorphism of eclogite facies has two stages: the co-esite eclogite facies stage (the peak condition: T = 600-700℃, P = 2. 7 - 3. 0 GPa) and theglaucophane eclogite facies stage (the pressure decreases, may be lower than 2. 5 GPa while thetemperature has little change). Low temperature eclogites (LT), as Group C, occur in the Qi-jiaoshan Formation. They were formed from blue schist facies (the peak condition: T = 490 -560℃, P< 1. 5 GPa). The appearance of hydrous minerals in the eclogites indicates the im-portant role of water in metamorphism. Medium-temperature eclogites are different from low-temperature ones in metamorphism. At last, the evolution of the high-pressure metamorphicbelt is discussed as well.
文摘厘清耕地演变的驱动机制对中国耕地资源可持续利用具有重要现实意义。该研究以鄂南地区为例,利用2000-2005、2005-2010和2010-2015年3期Landsat遥感影像解译成果、15类POI(Point of Interest)空间数据等,采用主成分分析、多元Logistic回归模型、边际效应分析等方法,系统分析了研究区近15 a以来耕地动态变化及其时空演变规律,并着重探讨了空间要素在驱动机制方面的双向边际效应。结果表明:1)耕地演变类型在空间上表现出相同类型的集聚性,转换类型受周边同类用地空间溢出效应影响明显。在时间上表现出不同转换类型的差异性,转换类型受土地利用政策宏观调控影响向建设用地单一转化趋势明显。2000-2015年间,耕地向建设用地的转换比例自28%过渡至44%后,迅速上升至96%,主要集中在城镇周边、主要道路沿线等区域。2)空间要素对不同时期耕地不同转化类型存在不同的边际效应,2000-2015年间耕地不同转化类型的边际效应变化幅度逐渐减小、不同转化类型边际效应曲线同类交点呈同向移动趋势。自然区位因素对耕地向建设用地转换和耕地向水域转换在POI空间要素不同取值时边际效应的变化较明显。3)空间要素边际效应曲线特征揭示其影响存在临界性,在临界值范围内,边际效应随着空间要素取值不同变化明显,但在临界值范围外,边际效应趋于稳定。耕地演变空间要素边际效应的定性定量分析对耕地布局优化与区域协调发展策略制定具有良好参考作用。
