| 华北地区冶里-亮甲山期层序地层及其岩相古地理 |
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| 引用本文： | 马学平,韩作振.华北地区冶里-亮甲山期层序地层及其岩相古地理[J].地质科学,1998,33(2):166-179. |
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| 作者姓名： | 马学平 韩作振 |
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| 作者单位： | 1. 北京大学地质学系 北京 100871;2. 山东矿业学院 泰安 271019 |
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| 摘 要： | 华北地区的冶里-亮甲山期地层由两个层序组成,“冶里”层序包括冶里组和亮甲山组底部的地层,相当于牙形石Utahconus beimadaoensis-Monocostodus sevierensis带至Scalpellodus tersus带,“亮甲山”层序包括其余的亮甲山组地层,相当于Serratognathus bilobatus带至Paraserratognathus paltodiformis带。由于海水由东北向南侵入,北部地区以海侵体系域及高位体系域发育为特征,主要属开阔海沉积,而南部及西部地区基本为高位体系域,主要属潮坪及局限海沉积,介于两者之间的曲阳-五台一带常以滩相为特征。这种体系域展布格局与生物地层相吻合。在晋南及豫北地区,常缺失海侵体系域的化石带,此外,由于每个层序结束时海退由南向北,因而南部地区又往往缺失高位期晚期或最晚期的地层。华北最北部,如河北平泉、秦皇岛一带,亮甲山组顶部见有一段在华北大部地区缺失的地层(Jumudontus gananda-Scolopodus sunanensis带),它代表了下一层序低位期间的沉积。随着海水再次由北向南侵入,结果形成了下马家沟组底部由北向南的超覆,也就是说,南部的贾汪组可能相当于北部下马家沟组的中下部,而不是底部。
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| 关 键 词： | 华北地区 下古生界 早奥陶世 层序地层 岩相古地理 |
| 收稿时间： | 1997-01-31 |
| 修稿时间： | 1997-01-31; |
THE TREMADOCIAN EARLY ARENIGIAN(EARLY ORDOVICIAN) SEQUENCE STRATIGRAPHY AND LITHOFACIES PALEOGEOGRAPHY OF NORTH CHINA |
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| Ma Xueping.THE TREMADOCIAN EARLY ARENIGIAN(EARLY ORDOVICIAN) SEQUENCE STRATIGRAPHY AND LITHOFACIES PALEOGEOGRAPHY OF NORTH CHINA[J].Chinese Journal of Geology,1998,33(2):166-179. |
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| Authors: | Ma Xueping |
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| Institution: | 1. Department of Geology, Peking University, beijing 100871;2. Shangdong Mining Institute, Tai’an, 271019 |
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| Abstract: | During Early Paleozoic the North China platform experienced two marine transgression-regression supercycles. The supercycle A represents a time span from Cambrian through early Arenigian of Early Ordovician. The Xinji age(equivalent to the Canglangpu age in the Chinese regional stratigraphic standard)through Xuzhuang age(Early Cambrian through early Middle Cambrian)features a general sea-level rise during which marine transgression generally followed a south to north direction; the Zhangxia through Gushan ages represent a persistent high sea-level period; from then on began a gradual regressive phase(middle Upper Cambrian through early Arenigian), till the end of which the North China platform(except for the northernmost part)was basically exposed. The supercycle B represents a time span from late Arenigian to early Caradocian. In the supercycle A, marine transgression and regression cycles often lead to frequent flooding and exposure of the nearshore areas of the platform. In contrast, in the supercycle B secondary sea-level rise and fall cycles did not result in distinct flooding and exposure of the nearshore areas, instead, the sea-level falls on the platform often produced lagoonal environments with widely distributed evaporite deposits. The Yeli and Liangjiashan Formations(Tremadocian Early Arenigian)of the North China platform are composed of two sequences. The "Yeli" sequence contains the Yeli Formation and basal part of the Liangjiashan Formation, which corresponds to conodont Utahconus beimadaoensis Monocostodus sevierensis Zone through Scalpellodus tersus Zone. The “Liangjiashan” sequence comprises the rest of the Liangjiashan Formation, which corresponds to conodont Serratognathus bilobatus Zone through Paraserratognathus paltodiformis Zone. Because of southwestward marine transgression from the northeast, the northern part of the platform is characterized by the transgressive system tracts and highstand system tracts, basically consisting of open marine deposits, whereas the southern and western parts mainly consist of highstand system tracts indicated by tidal flat and restricted marine deposits, between which such as in the Quyang Wutai area, the sequence is composed of shoal deposits. The above system tracts distribution pattern is coincident with the biostratigraphic zones of previous workers. Biozones of the transgressive interval are missing in the southern Shanxi and northern Henan region. In addition, late or latest highstand deposits are absent in the southern part due to northward regression from the south. At the northernmost part including Pingquan and Qinhuangdao of Hebei Province there still occurs a stratigraphic interval(Jumudontus gananda Scolopodus sunanensis Zone)which is missing in other parts at the top of the Liangjiashan Formation. This interval probably represents the lowstand deposits of the following sequence. The Jiawang Formation in the south should be correlated with the lower-middle part of the Lower Majiagou Formation in the north, instead of the base. |
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| Keywords: | North China Lower Paleozoic Early Ordovician Sequence stratigraphy Lithofacies paleogeography |
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