| 冀中中奥陶统高频率旋回层序的基本特征 |
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| 引用本文： | 王立峰.冀中中奥陶统高频率旋回层序的基本特征[J].沉积与特提斯地质,1994(6). |
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| 作者姓名： | 王立峰 |
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| 作者单位： | 河北地质学院 |
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| 摘 要： | 通过野外实测剖面及路线观察，河北中部中奥陶统马家沟群的高频率旋回可划分为三个级别，并与层序地层学术语可以对比，由低到高为；六级旋回──韵律层；五级旋回──准层序；四级旋回──准层序组。这些由米兰柯维奇驱动力所控制的旋回层序在不同的沉积环境中具有不同岩石组合特征，反映了高频率旋回的沉积模式。
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| 关 键 词： | 高频率旋回层序，沉积模式，中奥陶统，河北中部 |
MAIN CHARACTERISTICS OF THE MIDDLE ORDOVICIAN HIGH-FREQUENCY CYCLIC SEQUENCES IN CENTRAL HEBEI |
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| Wang Lifeng.MAIN CHARACTERISTICS OF THE MIDDLE ORDOVICIAN HIGH-FREQUENCY CYCLIC SEQUENCES IN CENTRAL HEBEI[J].Sedimentary Geology and Tethyan Geology,1994(6). |
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| Authors: | Wang Lifeng |
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| Institution: | Hebei College of Geology |
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| Abstract: | The Middle Ordovician high-frequency cyclic sequences in central Hebei are caused by the sea-level rises and' falls driven by the Milankovitch forces. In terms of the type and time duration of the Milankovitch cycles,three orders of the cycles corresponding to the terminology of sequence stratigraphy may be distinguished for the study area. (1) The sixth-order cyclic sequences are the products of precession Milankovitch rhythms with a time duration of 0. 02 Ma,corresponding to the cyclothems which may be assigned to four sedimentary models. (2) The fifth-order cyclic sequences are caused by eccentricity (E1)rhythms with a time duration of 0. 1 Ma,which correspond to the parasequences represented by thining- and thicking-upward depositional sequences and may be arranged in to six sedimentary models. (3) The fourth-order cyclic sequences are caused by eccentricity (E2)rhythms with a time duration of 0. 4 Ma,which correspond to the parasequence sets represented by shallowing-upward sequences. They are bounded by the marine-flooding surface at the base and exposure surface at the top, and consist of progradational, retrogradational and aggradational parasequence sets. According to the type and association,these parasequence sets may be assigned to three types of megacycles:aggradational megacycles-lowstand systems tract or shelf-margin systems tract ; retrogradational megacycles-transgressive systems tract,and progradational megacycles - highstand systems tract,which constitute the third-order cyclic depositional sequences. It is estimated, from the above-mentioned results,that the age of the Middle Ordovician Majiagou Group is about 19. 6 Ma. |
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| Keywords: | high-frequency cyclic sequence sedimentary model Middle Ordovician central Hebei |
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