Facies control on provenance shift during the early Cambrian transgression in Korea: Detrital zircon and geochemical evidence

Abstract

ABSTRACT The early Cambrian transgression that flooded continental margins worldwide produced extensive sedimentary records that archive valuable information about palaeogeography and basin dynamics. This study integrates detrital zircon U–Pb geochronology and wholerock geochemistry from the Myeonsan and Myobong formations of the basal Taebaek Group, which are correlated with detailed facies analysis, to investigate sedimentary dynamics along the eastern margin of the Sino‐Korean Block during this transgressive episode. Three distinct sediment sources are identified: (1) local Precambrian basement (2600 to 1800 Ma zircons, felsic), (2) a contemporaneous volcanic arc (~500 Ma zircons, mafic) and (3) distal Gondwanan terranes (1600 to 600 Ma zircons, felsic). The relative proportions of these sources evolved systematically through the transgressive succession, reflecting changing depositional environments and basin connectivity. Basal alluvial fan–fan delta deposits are dominated by locally derived sediments, followed by increasing volcanic arc contributions by tidal currents in estuarine–shallow subtidal environments. An abrupt transition from mafic to felsic geochemical signatures occurs within the deeper subtidal facies association, coinciding with maximum input from Gondwanan sources and likely representing a maximum flooding surface. This systematic variation in provenance signals demonstrates how progressive basin flooding altered sediment dispersal pathways, with the greatest mixing of diverse sources occurring during maximum marine influence. Our findings provide a framework for understanding how eustatic changes control provenance evolution in epicontinental seas, demonstrating the value of integrating multiple provenance indicators with facies analysis to develop comprehensive models of basin evolution during major transgressive episodes.

Affiliated Institutions

• Korea Institute of Geoscience and Mineral Resources KR
• Korea National University of Education KR
• Chungnam National University KR

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