Sedimentary Characteristics and Palaeoenvironmental Significance on Stromatolites of Mantou Formation in Cambrian, Western Henan, China

Key words: 
•   /
• stromatolites /
• sedimentary characteristics /
• distribution model of sedimentary environments /
• Mantou Formation /
• western Henan /
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•  /

Abstract:  From Cambrian in the first and second Member of Mantou Formation, 9 layers stromatolites are exposed, half of the 18 layers' in Cambrian in the western Henan province, China. The morphological characteristics are rich and notable, mainly columnshaped, wavyshaped, hemisphereshaped and surrounding flatpebble conglomerate limestones shaped, and it can be divided into 4 big and 8 small categories. On the basis of analyzing the characteristics of sedimentary facies of every beds of the first and second Member, Mantou Formation in Cambrian, western Henan Province, the distribution model of sedimentary environments has been established as 8 small categories and 11 types stromatolites in Mantou Formation through detailed description on the macro, meso morphological characteristics of different types of stromatolites and accompanying sedimentary structure. At the same time, the paper proved the distribution model of sedimentary environments with the growth environment of modern marine stromatolites and the sedimentary environment of Precambrian. The gently wavyshaped stromatolites are dominated by supratidal, with subordinate wavyshaped, small columnar and having horizontal thin bedded mud stromatolites. The wavyshaped, small columnar and having horizontal thin bedded mud stromatolites are dominated by upper intertidal, with subordinate conicalshaped stromatolites. The teretifolious stramatolites are dominated of middle intertidal having elliptical oncolites and flatpebble conglomerate, with subordinate conicalshaped and surrounding flatpebble conglomerate limestones shaped stromatolites. The teretifolious stramatolites having rounded oncolites and hemisphere shaped stromatolites are dominated of bottom intertidal to subtidal, with subordinate inverted conicalshaped stromatolites having oncolites. Sea level change i.e. hydrodynamic condition is the decisive factor of the stromatolites growth categories.