粤北丹霞盆地上白垩统陆相红层地球化学特征及其古气候意义OA

[Objective]The climate signals of the Danxia strata,a representative of Cretaceous continental red beds,offers key insights into red-bed sedimentation and Cretaceous geological events.[Methods]This study exam-ined fine-grained clastic rocks in the Upper Cretaceous Danxia Basin,specifically the Second member and Fourth member of the Changba Formation and the Jinshiyan member of the Danxia Formation.Sedimentology,elemental and isotopic geochemistry were used to investigate the sedimentary environment and paleoclimate significance during key Upper Cretaceous stages(Cenomanian,Turonian,Campanian).[Results]It was found that the fine-grained clastic rocks of these formations were deposited during a warm and humid climate phase,with suboxic to oxic water condi-tions.The water bodies were predominantly brackish,while localized high-salinity brackish and low-oxygen environ-ments(e.g.,the Fourth member of the Changba Formation)were associated with lake shrinkage and climatic aridifi-cation.Water depth variations exhibit trends of initial contraction followed by expansion,gradual contraction,then initial expansion followed by contraction,which align with the changes in sedimentary facies and environment.[Con-clusions]The Upper Cretaceous terrestrial sedimentary records of the Danxia Basin illustrate the climatic evolution of intermontane basins,shaped by global climate patterns of the Upper Cretaceous,as well as by significant influenc-es from local topographic and geomorphic features.