西秦岭泥盆纪西汉水群、三叠纪隆务河群叠加褶皱的存在证据及地质意义
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摘要
在西秦岭泥盆纪、三叠纪地层中普遍存在着叠加褶皱,由于覆盖和两期褶皱的近共轴特征,使得这种叠加褶皱的识别和填绘长期未能得到合理解决。多期面理的识别和空间关系、小褶皱枢纽和轴面产状统计,为叠加褶皱的存在提供了依据。地质体平面形态的透镜化和走向弯曲,是两期叠加褶皱干涉图象的平面特征。有效解析叠加褶皱,合理建立构造模型,不仅对区域构造发展的历史具有重大意义,在指导地质填图工作的进行方面也具有不可替代的作用。甘肃西秦岭地区大面积分布的泥盆纪西汉水群和三叠纪隆务河群,以浅变质和砂板岩夹灰岩的沉积建造为特点,地质填图中厚度巨大的假象是叠加褶皱构造叠置所成,是构造复合的结果。多期面理关系的研究和小褶皱枢纽产状的统计分析,认为有两期近共轴、小角度的褶皱叠加。
There are lots of superposed f olds among Devonian Xihanshui Group and Triassic Longwuhe Group expansively outcropped in west Qinling region of Gansu Province. The stratigraphy are sedimentary formation of light metamorphic sand slate with limestone. Due to covering and near coaxial features of two periods folds, the issue of recognition and mapping these superposed folds are not resolved. By recognizing, collecting and analyzing special relation of multi-period foliation, the occurrence of hinge and axial surface of wrinkling will provide existence evidence of superposed folds. The plan modality of geological body has the appearance of lens and curved strike which are the feature of interference pattern of superposed folds caused by two stage movement.It will be significance for interpreting the regional tectonic evolution by analyzing superposed folds and establishing geological structural model. The large and thick false geological body on geological map is due to superposition of folds, it is the product of re recombined structures.
There are lots of superposed f olds among Devonian Xihanshui Group and Triassic Longwuhe Group expansively outcropped in west Qinling region of Gansu Province. The stratigraphy are sedimentary formation of light metamorphic sand slate with limestone. Due to covering and near coaxial features of two periods folds, the issue of recognition and mapping these superposed folds are not resolved. By recognizing, collecting and analyzing special relation of multi-period foliation, the occurrence of hinge and axial surface of wrinkling will provide existence evidence of superposed folds. The plan modality of geological body has the appearance of lens and curved strike which are the feature of interference pattern of superposed folds caused by two stage movement.It will be significance for interpreting the regional tectonic evolution by analyzing superposed folds and establishing geological structural model. The large and thick false geological body on geological map is due to superposition of folds, it is the product of re recombined structures.
引文
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[2]陈龙,施炜.叠加褶皱研究进展综述[J].地质力学学报,2014,20(4):455-464.
[3]吴德超,王道永,邓江红,等.变质岩区褶皱构造恢复的方法与实践——以新疆北山高尖地区为例[J].世界地质,2002,21(3):218-227.
[4]田作基.沉积岩区叠加褶皱及其成因机制[J].西北地质,1994,15(1):5-10.
[5]单文朗.构造变形分析的理论方法和实践[M].中国地质大学出版社,1991:12-17.
[6]黄继钧.叠加褶皱的类型及变形图像[J].成都地质学院学报,1988,15(4):40-46.
[7]管树巍,李本亮,何登发,等.复杂构造解析中的几何学方法与应用[J].地质科学报,2007,42(4):722-739.
[8]黄继钧.纵弯叠加褶皱地区岩石有限应变特征——以川东北地区典型叠加褶皱为例[J].地质论评,2000,46(2):178-185.
[9]黄继钧.纵弯叠加褶皱地区应力场研究——以川东北地区典型叠加褶皱为例[J].地质科学,2000,35(2):140-150.