Internal-wave and Internal-tide Deposits in the Paleostratigraphic Record of the Western Qinling Mountains and Their Origin

JIN Hui-juan; LI Yu-ci; FANG Guo-qing

Internal-wave and internal-tide deposits are akind of dragging-flow deposits recently found in ancient deep-sea environments. A variety of internal-wave and internal-tide deposits has been identified in the deep-sea deposit along the Hercynian-Indosinian orogeny of the western Qinling Mountains. According to their depositional structures they can be divided into 7 microfacies, 1. Fine- and medium-grained sandstone with bi-directional cross-bedding structure, 2. Siltstone with pinnate cross-lamination structure, 3. Siltstone with fascicular lens superposed cross-lamination structure, 4. Siltstone with complicatedly interweaving bi-directional cross-lamination structure, 5. Siltstone with bi-directional cross-lamination structure, 6. Sand and mud interbed with wave-, vein-and lens-like composite stratification, and 7. Fine sandstone with wave and ripple structure. The present study shows that they are formed in deep-sea turbidite systems of 3 different environments. The distribution of internal-wave and internal-tide deposits in deep sea is characterized by generality, non-abundance and evident selection for layers. All of these characteristics are closely related with their formation and preservation conditions.

Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou 730000

Received Date: 2001-06-01

Key words:

interal-wave and internal-tide deposits /
ancient deep-stratum /
West Qinling Orogenic Belt

Abstract: Internal-wave and internal-tide deposits are akind of dragging-flow deposits recently found in ancient deep-sea environments. A variety of internal-wave and internal-tide deposits has been identified in the deep-sea deposit along the Hercynian-Indosinian orogeny of the western Qinling Mountains. According to their depositional structures they can be divided into 7 microfacies, 1. Fine- and medium-grained sandstone with bi-directional cross-bedding structure, 2. Siltstone with pinnate cross-lamination structure, 3. Siltstone with fascicular lens superposed cross-lamination structure, 4. Siltstone with complicatedly interweaving bi-directional cross-lamination structure, 5. Siltstone with bi-directional cross-lamination structure, 6. Sand and mud interbed with wave-, vein-and lens-like composite stratification, and 7. Fine sandstone with wave and ripple structure. The present study shows that they are formed in deep-sea turbidite systems of 3 different environments. The distribution of internal-wave and internal-tide deposits in deep sea is characterized by generality, non-abundance and evident selection for layers. All of these characteristics are closely related with their formation and preservation conditions.

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Reference (8)

[1]	Gao Zhenzhong,Eriksson K A.Internal-tide deposits in an Ordovician submarine channel:Previously unrecognized facies?[J].Geology,1991,19(7):734～737
[2]	高振中,何幼斌,李建明等.我国发现内潮汐沉积[J].科学通报,1997,43(3):1418～1421
[3]	高振中,何幼斌,张兴阳等.塔中地区晚奥陶世内波、内潮汐沉积[J].沉积学报,2000,18(3):400～407
[4]	Narayan J.Sedimentary structures in the Lower Greensand of the Weald,England,and Ras-Boulonnais,France[J].Sedim.Geol.,1971,6:73～109
[5]	晋慧娟,李育慈.深海沉积中的几种"特殊"原生沉积构造[J].中国科学(B辑),1995,25(8):890～896
[6]	晋慧娟,李育慈.西秦岭造山带中三叠统复理石相研究[J].沉积学报.2001,19(3):321～326
[7]	晋慧娟,李育慈.西秦岭北带泥盆系含金层段沉积环境的新认识[J].科学通报,1997,42(2):183～186
[8]	高振中等.深水牵引流沉积--内潮汐、内波和等深流沉积研究[M].北京:科学出版社,1996

[1]	Gao Zhenzhong,Eriksson K A.Internal-tide deposits in an Ordovician submarine channel:Previously unrecognized facies?[J].Geology,1991,19(7):734～737
[2]	高振中,何幼斌,李建明等.我国发现内潮汐沉积[J].科学通报,1997,43(3):1418～1421
[3]	高振中,何幼斌,张兴阳等.塔中地区晚奥陶世内波、内潮汐沉积[J].沉积学报,2000,18(3):400～407
[4]	Narayan J.Sedimentary structures in the Lower Greensand of the Weald,England,and Ras-Boulonnais,France[J].Sedim.Geol.,1971,6:73～109
[5]	晋慧娟,李育慈.深海沉积中的几种"特殊"原生沉积构造[J].中国科学(B辑),1995,25(8):890～896
[6]	晋慧娟,李育慈.西秦岭造山带中三叠统复理石相研究[J].沉积学报.2001,19(3):321～326
[7]	晋慧娟,李育慈.西秦岭北带泥盆系含金层段沉积环境的新认识[J].科学通报,1997,42(2):183～186
[8]	高振中等.深水牵引流沉积--内潮汐、内波和等深流沉积研究[M].北京:科学出版社,1996

Internal-wave and Internal-tide Deposits in the Paleostratigraphic Record of the Western Qinling Mountains and Their Origin

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