SEQUENCE STRATIGRAPHIC IMPLICATION OF THE NAPENG FORMATION EXPOSED AT NAPENG – NAMON AREA, KYAUKME TOWNSHIP, NORTHERN SHAN STATE
Abstract
- Napeng-Namon area is mainly consisting of carbonate and silicilastic sedimentary rocks of Late Permian to Late Triassic age. In this paper, lithofacies and sequence stratigraphy of the Late Triassic of Napeng Formation are studied in detail. The sequence boundary between Nwabangyi Dolomite Formation and Napeng Formation is type I sequence boundaries (SB) which is represented by a significant unconformity. In the present study, the Napeng section contains stacked depositional cycles consisting of characteristic succession of sedimentary facies and facies associations. Based on detailed measurement, these sliciclastic-carbonate facies are deposited by shallow marine tidal current. Seven fourth-order shallowing upward, parasequence cycles can be recognized by environmental changes within Napeng section; by the graduality of the change in lithology, facies composition and faunal content. Features formed during the transgression, such as hardgrounds, iron-stained surface, and mollusk bearing siltstone are more prominent than the subaerial exposure features. Sequence in these outcrops display fewer paleokarst features and more pyritized and erosional hardgrounds at flooding surfaces and transgressive surfaces. The deposition of the Late Triassic (Napeng Formation) can be regarded as the progradational stacking pattern with some aggradations and these homoclinal ramp stack may show vertical accretion, but individual sequence seldom develop in a keep-up style.
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Year
- 2020
Author
-
Cho Cho Lwin
Subject
- Geology
Publisher
- Myanmar Academy of Arts and Science (MAAS)