Sediment Provenance and Depositional Response to Multistage Rifting, Paleogene,Huizhou Depression,Pearl River Mouth Basin
Wang Wei
Ye Jiaren
Yang Xianghua
Shi Hesheng
Shu Yu
Wu Jing
Abstract：In order to clarify the controlling effects of tectonic activities on the sediment supply and sedimentary filling,the sediment supply of the Huizhou depression is quantitatively studied by analyzing the changes in the shape and chronology of the detrital zircons of eight samples from different formations,with LA-ICPMS zircon U-Pb dating as the main measuring method.The southern provenance areas,Dongsha Massif and the internal uplifts of the basin,are predominantly composed of Mesozoic igneous rocks,while northern provenance areas,South China folded belt,are characterized by complicated lithology and geochronology.The results show that the content of Mesozoic zircon grains decreases while that of Precambrian-Paleozoic zircon grains increases and then prevails gradually from the Lower Wenchang Formation to the Upper Wenchang Formation and to the Enping Formation,confirming that the area provenance system switched a south provenance in the basin to a north provenance out of the basin gradually.The evolution of Huizhou depression in Paleogene can be divided into three rifted stages:periodsⅠA ,ⅠB andⅡ.During periodⅠA(Lower Wenchang Formation),the southernfaults of depression suffered strong activities.All zircon grains are derived from Mesozoic,indicating sediments derived from the south-ern provenance areas.The related sedimentary facies are characterized by fan delta and middle-deep lake under the conditions of south-ern steep slope of Huizhou depression.During period IB ,corresponding to Upper Wenchang Formation,the tectonic activities are char-acterized by high subsidence rates in the northern fault zones.The content of Mesozoic grains is 68%,whereas the content of Precam-brian-Paleozoic zircon grains is up to 32%,which indicates that sediments are derived from both northern and southern provenance are-as.The related sedimentary facies have the characteristics of fan delta,braided river delta and middle-deep lake.During periodⅡ(En-ping Formation),the northern faults stayed active.The content of Precambrian-Paleozoic zircon grains increases to 64% while that of Mesozoic grains decreases to 36%,which indicates that northern provenance areas play a dominant role in this stage.In addition,the related sedimentary facies are characterized by shallower braided river delta,beach bar and thin coal seam.
Keywords：Huizhou depressionmultistage riftingprovenance switchingzircon U-Pb datingsedimentsgeochronology
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 1061-1071 )