摘要
鲁西伸展构造的主要特征是发育掀斜断块，断块由凸起和凹陷组成，凹陷部分的半地堑盆地，走向由ＮＷ转为ＥＷ，北深南浅，地层关系北断南超，沉积中生界和老第三系，盆地基底是前寒武纪结晶岩石和古生界。由侏罗纪至老第三纪，伸展构造的活动持续了约１５０Ｍａ。在如此长的时间里要保持掀斜断块运动特征的一致性，除了区域性的伸展运动特征保持不变外，掀斜断块本身的均衡性不被破坏是必须的。断块的密度在掀斜过程中不会有多大改变，保持均衡的关键在于断块的大小、形状和空间方位不发生过大变化；而掀斜断块发育剥蚀端和沉积楔，以及相应的在地下部分发育增生楔和削蚀端，可以满足这样的条件。河南和安徽区段发育同类型构造，它们与鲁西伸展构造联合显示出一个规模宏大的伸展构造系统，从而证明鲁西－淮河平原中－上地壳板块的存在。这个板块的前缘消减现象明显，发育压剪带，“大别山块体”可能是“挤出体”。
The basic feature of Luxi extensional structure is the development of lifted-dipping blocks which are made up of swell and sag. The semi-gvaben basin in sag area has a strike changingfrom NW to EW,deep in north and shallow in south depth and stratigraphic relationships offaulting in north and overlapping in south. Its sedimenfary rocks Consist of mesozoic erathem andtertiary System. The basin basement Comprise precambrian crystalline rocks and palaeogoicerathem. From Jurassic to Palaogene the extensional structure lasted about 150 Ma in activestate . In so long time for maintaining the consistency of movement natures of lifted-dippingblocks besides the Constant regional extensional movement it is also necessary that the isostacy oflifted-dipping blocks by selves was wot destroyed.The density of lifted-dipping blocks didn’tevidenty change during the lifted-dipping process. Whereas the key to maintain the isostacy liesin that the scal, form and space distribution of the blocks were not significantly changed. Suchconditions can be reached if the lifted-dipping blocks developed eroded end and sedimentarywedge and in correspondence in their subground portion there developed accretionary wedge andcut-off end. The structures of the same type develop in Henan and Anhui segment. They withLuxi extensional structure in commen constitute a vast extensional structure system by which theexistence of the middle-upper crust plate in Luxi-Huaihe plain is confirmed,This plate hasobvious phenomenon of front subduction and a transgressional belt developed. The“DabieshanBlock'may be its“extruded body”。
出处
《山东地质》
1995年第2期23-31,共9页
Geology of Shandong
