In North China, the Mesozoic terrestrial basins, sedimentary palaeogeography and tectonic settings involved five evolutionary stages:(1) the Early-Middle Triassic,(2) the Late Triassic to Early-Middle Jurassic,(3) the Late Jurassic to early Early Cretaceous,(4) the middle-late Early Cretaceous and(5) the Late Cretaceous. The regional punctuated tectonic events occurred during these evolutionary stages. During the Early-Middle Triassic(stage 1), the Xingmeng Orogenic Belt(XMOB, i.e., eastern part of Central Asia Orogenic Belt, CAOB) of the northern North China was settled in the transition of tectonic environment from syn-orogenic compression to post-orogenic extension with intensive uplifting. It is a main provenance in the unified Ordos-North China Basin.The united continental plate of China and the Qinling-Dabie-Sulu Orogenic Belt formed due to convergence and collision between the North China Plate and the Yangtze Plate along two suture zones of the Mianlue and the Shangdan in the terminal Middle Triassic. During the Late Triassic to the Early-Middle Jurassic(stage 2), the Late Triassic mafic or alkaline rocks and intrusions occurred on the northern and southern margins of North China Craton(NCC) and XMOB, implying that intensified extension happened all over the North China(early phase of stage 2). Additionally, in the late phase of stage 2, the basic volcanicfilling faulted basins were widely distributed in the northeastern North China during the EarlyMiddle Jurassic, including a series of small- to medium-sized basins with coal-bearing strata and some volcanic rocks in other areas of North China, which was the result of subduction of the Palaeo-Pacific Plate during the Early-Middle Jurassic. An active continental margin with accretionary complex developed in the eastern Heilongjiang of China, Japan and the Far East of Russia at that time. However, in the end of the Early-Middle Jurassic, because of the Yanshanian orogeny characterized by complicated thrust and fold, the previous unified OrdosNorth China Bas
Yong-Qing LiuHong-Wei KuangNan PengHuan XuPeng ZhangNeng-Sheng WangWei An
The mass burial of dinosaur bone fossils in the Late Cretaceous Wangshi Group in Zhucheng,Shandong Province has been a research focus in recent years.However,the provenance of the dinosaur bone fossils and the accurate depositional age of the bone beds remain ambiguous.Through U-Pb dating of detrital zircons collected from six conglomerate samples from the dinosaur bone beds,we found that the youngest single grain age(YSG) of sample 090414-24-D was 77.3 Ma,representing the maximum depositional age of the dinosaur fossil beds and sediments.This also indicates that the Hongtuya Formation was deposited during the Campanian.Dating results revealed an age peak of 120-110 Ma,which corresponds with the peak age of volcanic rocks of the Lower Cretaceous Qingshan Group.The volcanic rocks of the Qingshan Group are mainly exposed in Laiyang,to the north of Zhucheng,although a few also appear to the south and northwest.Through analysis of conglomerate composition and palaeocurrents in the sediments containing the bone beds,we found that the three different data sets of gravel compositions of the conglomerates were mainly composed of volcanic or pyroclastic rocks.Three different data sets of palaeocurrents suggested that the main sediment source of the Wangshi Group dinosaur bone beds was from the north-northwest of the Basin.Only one data set had a provenance south of the basin.This study revealed that the areas of Laiyang and the Yishu Fault Zone were the main provenance areas of both the dinosaur bone fossils and the sediments of the Wangshi Group in Zhucheng.The southern margin of the Zhucheng Basin may be a secondary source area.This research provides an important basis for judging the deposition time and the sediment source of fossil layers in the Wangshi Group,as well as reconstructing the palaeogeography of the Wangshi Group in the Jiaolai Basin.
