大连上震旦统地震灾变事件研究
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摘要
笔者在大连工作区的上震旦统南关岭组、甘井子组和营城子组碳酸盐岩地层中,识别出以震动液化脉、震动液化角砾岩、碳酸盐岩浊积岩等震积岩为代表的古地震灾变事件层(工作区缺失上震旦统顶部的兴民村组震积岩),这在工作区属首次发现。这一发现进一步提高了辽南震旦系的研究程度,证明了辽南地区晚震旦世存在4个地震活跃期,从而为区域地层对比提供了新的实际材料。新发现的甘井子组白云岩中的地震灾变事件层表现为白云石质的震动液化脉及液化卷曲变形,是对辽南震旦系研究程度的提高和丰富。
It was disputed whether the Neoproterozoic in the Dalian (including Lushun) area of the southern Liaodong Peninsula is at the same horizon as that in the northern Liaodong Peninsula because the former has been intensively deformed and "the later" has not been deformed. Recently, the authors have identified, in the carbonate rock strata of the Upper Sinian Nanguanling, Ganjingzi and Yingchengzi Formations in the study area, vibrate liquefied veins, vibrate liquefied breccias and carbonate turbidites with seismite successions resulting from earthquakes. All the new discoveries in the above area have promoted the study of Sinian in southern Liaodong Peninsula and revealed that there existed 4 instead of 3 earthquake-active periods in the Late Sinian there. In addition, the discoveries have also provided new information for regional stratigraphic correlation. The general character of the Upper Sinian seismic events in the study area is observed as that the seismic beds consisting of carbonates with liquefied veins and breccias are alternated with the normal carbonates at the interval of two seismic events. Their similarity with those observed in the Red Sea, Egypt indicates that they are also products of earthquakes. The seismites in the Nanguanling and Yingchenzi Formations are composed of limestones and ooid bearing micrites with liquefied veins and breccias, limestones with cracks and grainstones with grade bedding (turbidites). Those in the Ganjingzi Formation consist of dolomites with liquefied veins and breccias and roll up deformed structures. So the commonest type of seismites in the area are carbonates with liquefied veins and breccias. The liquefied veins are made up of equal sized, purified and crystallized carbonate grains, while the liquefied breccias are simple in composition and can be pieced together. Both of them are often associated with cracks and deformations. The 4 seismic strata in Dalian, an intensively deformed area, can also be observed in corresponding strata in the northern Liaodong Peninsula (Wafangdian City,the Fuzhou area), which indicates that the two areas belong to the same depositional basin. The above fact provides evidence of seismic events for making stratigraphic comparison of the two areas in the Sinian in regional mapping at scales of 1 : 50000 and 1 : 250000. The dolomite liquefied veins and liquefied roll up deformation structures in the Ganjingzi Formation are identified as a result of another new seismic event. So new materials are given in this paper for comparing the strata of this area to those of others. The study of Sinian strata in the Liaodong Penesula are promoted in addition to enrichment of the sorts of seismites and the succession system in theory.
It was disputed whether the Neoproterozoic in the Dalian (including Lushun) area of the southern Liaodong Peninsula is at the same horizon as that in the northern Liaodong Peninsula because the former has been intensively deformed and "the later" has not been deformed. Recently, the authors have identified, in the carbonate rock strata of the Upper Sinian Nanguanling, Ganjingzi and Yingchengzi Formations in the study area, vibrate liquefied veins, vibrate liquefied breccias and carbonate turbidites with seismite successions resulting from earthquakes. All the new discoveries in the above area have promoted the study of Sinian in southern Liaodong Peninsula and revealed that there existed 4 instead of 3 earthquake-active periods in the Late Sinian there. In addition, the discoveries have also provided new information for regional stratigraphic correlation. The general character of the Upper Sinian seismic events in the study area is observed as that the seismic beds consisting of carbonates with liquefied veins and breccias are alternated with the normal carbonates at the interval of two seismic events. Their similarity with those observed in the Red Sea, Egypt indicates that they are also products of earthquakes. The seismites in the Nanguanling and Yingchenzi Formations are composed of limestones and ooid bearing micrites with liquefied veins and breccias, limestones with cracks and grainstones with grade bedding (turbidites). Those in the Ganjingzi Formation consist of dolomites with liquefied veins and breccias and roll up deformed structures. So the commonest type of seismites in the area are carbonates with liquefied veins and breccias. The liquefied veins are made up of equal sized, purified and crystallized carbonate grains, while the liquefied breccias are simple in composition and can be pieced together. Both of them are often associated with cracks and deformations. The 4 seismic strata in Dalian, an intensively deformed area, can also be observed in corresponding strata in the northern Liaodong Peninsula (Wafangdian City,the Fuzhou area), which indicates that the two areas belong to the same depositional basin. The above fact provides evidence of seismic events for making stratigraphic comparison of the two areas in the Sinian in regional mapping at scales of 1 : 50000 and 1 : 250000. The dolomite liquefied veins and liquefied roll up deformation structures in the Ganjingzi Formation are identified as a result of another new seismic event. So new materials are given in this paper for comparing the strata of this area to those of others. The study of Sinian strata in the Liaodong Penesula are promoted in addition to enrichment of the sorts of seismites and the succession system in theory.
引文
Frank T D, Lyons T W. 1998． " Molar-tooth" structures: A geochemical perspective on a Proterozoic enigma. Geology, 26 (8) :683～686．
Guiraud M, Plaziat J C. 1993． Seismites in the fluviatile Bima sandstones: identification of paleoseisms and discussion of their magnitudes in a Cretaceous synsedimentary strike-slip basin (Upper Benue, Nigeria). Tectonophysics, 225: 493～522．
Plaziat J C, Purser B H, Philobbos E. 1990． Seismic deformation structures (seismites) in the syn-rift sediments of the NW Red Sea (Egypt). Bull. Soc. Geol. France, (8) : 419～434．
Plaziat J C, Ahmed E. 1993． Diversity of the sedimentary expressions of major earthquakes: An example from the Pliocene sandy seismites of the Egyptian Red Sea coast.
Qiao Xiufu, Song Tianrui, Gao Linzhi, Peng Yang, Li Haibing, Gao Mai, Song Biao, Zhang Qiaoda. 1994． Seismic sequence in carbonate rocks by vibrational liquefaction. Acta Geologica Sinica (English Edition), 7(3) : 243～265．
Qiao Xiufu, Gao Linzhi, Gao Mai, Fu Guomin, Yin Changjian, Xie Xueguang, Zhou Xiaodong, Chen Yuejun. 1995． Outcrop sequence stratigraphy of the Neoproterozoic in the Hunjiang area,Jilin Province. Regional Geology of China, (2) : 99～111 (in Chinese with English abstract).
Qiao Xiufu, Song Tianrui, Li Haibing, Gao Linzhi. 1996a. Genetic stratigraphy of the Sinian and lower Cambrian strata in south Liaoning Province. Beijing:Science Press (in Chinese with English abstract).
Qiao Xiufu, Ji Qiang, Gao Linzhi, Gao Zhenjia. 1996b. Stratigraphic correlation of the Sinian in the eastern part of the Northern China Plate. Regional Geology of China, (2) : 136～142 (in Chinese with English abstract).
Guiraud M, Plaziat J C. 1993． Seismites in the fluviatile Bima sandstones: identification of paleoseisms and discussion of their magnitudes in a Cretaceous synsedimentary strike-slip basin (Upper Benue, Nigeria). Tectonophysics, 225: 493～522．
Plaziat J C, Purser B H, Philobbos E. 1990． Seismic deformation structures (seismites) in the syn-rift sediments of the NW Red Sea (Egypt). Bull. Soc. Geol. France, (8) : 419～434．
Plaziat J C, Ahmed E. 1993． Diversity of the sedimentary expressions of major earthquakes: An example from the Pliocene sandy seismites of the Egyptian Red Sea coast.
Qiao Xiufu, Song Tianrui, Gao Linzhi, Peng Yang, Li Haibing, Gao Mai, Song Biao, Zhang Qiaoda. 1994． Seismic sequence in carbonate rocks by vibrational liquefaction. Acta Geologica Sinica (English Edition), 7(3) : 243～265．
Qiao Xiufu, Gao Linzhi, Gao Mai, Fu Guomin, Yin Changjian, Xie Xueguang, Zhou Xiaodong, Chen Yuejun. 1995． Outcrop sequence stratigraphy of the Neoproterozoic in the Hunjiang area,Jilin Province. Regional Geology of China, (2) : 99～111 (in Chinese with English abstract).
Qiao Xiufu, Song Tianrui, Li Haibing, Gao Linzhi. 1996a. Genetic stratigraphy of the Sinian and lower Cambrian strata in south Liaoning Province. Beijing:Science Press (in Chinese with English abstract).
Qiao Xiufu, Ji Qiang, Gao Linzhi, Gao Zhenjia. 1996b. Stratigraphic correlation of the Sinian in the eastern part of the Northern China Plate. Regional Geology of China, (2) : 136～142 (in Chinese with English abstract).
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