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郯庐断裂带肥东段西韦地区和桃花源地区出露了大规模的北北东向韧性剪切带。桃花源地区韧性剪切带显示出2期构造变形的叠加。野外构造和显微构造分析皆指示为左行走滑韧性剪切带。糜棱岩中石英与长石的变形行为指示其变形温度分别为400~450℃和500℃。通过对这两处走滑剪切带内糜棱岩化花岗岩脉的锆石LA-ICP-MS定年,获得了3个样品的侵位年龄分别为(133.2±1.9)Ma,(131.3±2.0)Ma,(130.3±2.0)Ma。再结合已有的研究成果,认为在128~124Ma(早白垩世中期)郯庐断裂带发生过左行走滑活动。综合分析表明,郯庐断裂带在晚侏罗世和早白垩世中期分别经历了2期左行走滑活动,而期间和之后的早白垩世则处于伸展活动之中。伸展活动持续较长,控制发育了西侧的合肥盆地及断裂带内一系列岩浆活动;而区域挤压背景下出现的走滑活动则相对短暂。这些演化规律显示该断裂带在晚侏罗世—早白垩世呈现为交替式的走滑和伸展活动。新发现的早白垩世中期走滑活动,与太平洋区伊泽纳崎板块板块运动方向的调整相对应,是大洋板块运动方向短暂调整的构造响应。
The east Weihe area and the Peachuanyuan area of the eastern section of the Tancheng-Lujiang fault zone have exposed large-scale north-east direction ductile shear zones. The ductile shear zone in the Taoyuan area shows the superimposition of structural deformations in the second phase. The field structure and microstructure analysis are both indicated as left-slip ductile shear zones. The deformation behavior of quartz and feldspar in mylonites indicates that the deformation temperature is 400 ~ 450 ℃ and 500 ℃ respectively. Through the LA-ICP-MS zircon dating of the mylonitized granite veins in the two strike-slip shear zones, the emplacement ages of the three samples were (133.2 ± 1.9) Ma and (131.3 ± 2.0) Ma, (130.3 ± 2.0) Ma. Combined with the existing research results, it is considered that the left-lateral strike slip occurs in the Tanlu fault zone from 128 to 124 Ma (mid-Early Cretaceous). The comprehensive analysis shows that the Tancheng-Lujiang fault zone experienced two left-lateral strike-slip events in the Late Jurassic and Early Cretaceous, respectively, while the Early Cretaceous during and after the extension was in extension. The extensional activities continued for a long time, controlling the development of a series of magmatic activities in the Hefei basin and fault zone on the west side. However, the slippage activities in the area of crustal extrusion were relatively short-lived. These evolutionary laws show that the fault zone presented alternating strike-slip and extension activities during the Late Jurassic-Early Cretaceous. The newly discovered mid-early Cretaceous slip event corresponds to the adjustment of the direction of the Izanagas plate movement in the Pacific Ocean and is a tectonic response to the temporal adjustment of the direction of the ocean plate movement.