龙门山地区泥盆纪海平面升降规程、频幅及对比

FREQUENCY, AMPLITUDE, AND PATTERN OF SEA LEVEL CHANGES IN DEVONIAN IN LONGMEN MOUNTAINS, WESTERN YANGTZE

龙门山地区泥盆纪海平面升降由三个准二级旋回叠加组成：第一个含Ｓ１～Ｓ３层序所对应的三个海平面升降旋回；第二个、第三个分别含Ｓ４～Ｓ１０六个和Ｓ１１～Ｓ１８八个层序映射的三级海平面组合而成。海平面升降频幅样式可识别低频低幅、高频低幅、低频高幅、高频高幅四种类型，整个泥盆纪表现为早晚期低频低幅型，中期则以另外三种混合叠加为主。最高、最低海平面对比显示全球各大陆具不等时性，全球海平面升降规程则具相似性。

Eighteen cycles of sea level rising and falling are recognized in Devonian in Longmen Mountains , western Yangtze. They are superposed to be three para 2nd order cycles and one 2nd order cycle, in which four types of frequency (Fm) - amplitude (Am) of sea level rising and falling can be distinguished as low Fm - low Am, high Fm - low Am, low Fm - high Am, and high Fm - high Am. The Devonian relative sea level changes in time gradient, the characteristic of undulation from gentle rising and long duration to stable falling and short duration are consistent with those all over the world at the same time, although the stratigraphic horizon of the highest and lowest stands are different. The highest stand horizon in Longmen Mountains, the Tuqiaozi Formation, is in the mid lower asymmetricus zone in the early Frasnian that is lower than that in western Qingling Mountain, Euramerica , and higher than that in southwestern Siberia; the lowest stand horizon, the top of Pingyipu Formation, is roughly in the mid upper kindlei zone in Pragian which is earlier than that in Euramerica , Siberia and South China. At the end of the paper, some problems and significances on the pattern, frequency, amplitude and benthic water depth curve are discussed.