国际地层委员会将中元古界底界界线年龄定为1600 Ma,1600～1400 Ma为Calymmian（盖层系）,表示全球地台盖层形成时期.华北地台基底固结时间为1800Ma,固结后即进入伸展裂解作用时期,首先是山西吕梁山区、晋南中条山、豫西熊耳山区裂解发...国际地层委员会将中元古界底界界线年龄定为1600 Ma,1600～1400 Ma为Calymmian（盖层系）,表示全球地台盖层形成时期.华北地台基底固结时间为1800Ma,固结后即进入伸展裂解作用时期,首先是山西吕梁山区、晋南中条山、豫西熊耳山区裂解发展成三叉裂陷槽（Aulacogen）.吕梁山区小两岭组火山岩形成年龄有1778±20 Ma（SHRIMP U Pb锆石）及1779±20 Ma（LA ICP MS U Pb锆石）两个数值;豫西熊耳群顶部马家河组和中部鸡蛋坪组及下部许山组火山岩年龄分别为1776±20 Ma、1791±20 Ma和1783±13 Ma（SHRIMP U Pb锆石）,1776～1800Ma为火山岩的形成年龄;将1800Ma作为小两岭组与熊耳群两个火山岩组的底界年龄应当是合理的.吕梁山区的汉高山群为碎屑岩夹火山岩,代表吕梁陕豫三叉裂陷槽北支中的快速充填,与小两岭组为同时期沉积.汉高山群、大古石组（熊耳群底部沉积岩）为1800Ma裂解开始的盖层沉积,小两岭组火山岩、相关的辉绿岩墙及熊耳群火山岩均为裂解时期的岩浆作用产物.北京密云环斑花岗岩侵位时间为1700Ma,代表燕山太行山裂陷槽裂解的起始时间也即燕山地区长城系常州沟组底界年龄.北京密云地区环斑花岗岩风化壳上覆常州沟组年龄可确定为1650Ma,它不应被看作常州沟组最低层位的年龄,而是裂陷槽裂解后密云地区开始接受沉积的年龄,1700Ma、1650Ma代表常州沟组在不同地区的底界年龄,但均不等于长城系或中元古界的底界年龄.1600Ma为高于庄组底界年龄,即长城系与蓟县系的界线年龄,也是国际地层委员会中元古界的底界年龄.1600 Ma代表燕山太行山裂陷槽闭合的年龄,也是华北地台始自1800Ma伸展裂解作用的最终结束时期.1600Ma是新的陆表海盆地发展的起始时间,是重要的华北地台构造转换的时期.因此,1800与1600 Ma代表华北地台重大地质构造事件的年龄,具大区域构造意义,依据对前寒�展开更多
In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproteroz...In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (~1 600-1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely shaped like Chuaria Shouhsiennia (Ellipsophyta) and Tawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namely Chuaria- and Shouhsienia-llke forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply a very important basis in histology to determine the展开更多
The paleoflow direction of the basal conglomerate of the Changzhougou formation is obtained by the paleocurrent analysis of certain sedimentary structures,and the ancient sedimentary environment of the Qian’an Region...The paleoflow direction of the basal conglomerate of the Changzhougou formation is obtained by the paleocurrent analysis of certain sedimentary structures,and the ancient sedimentary environment of the Qian’an Region is determined by observing the psephicity and gradation of gravel in conglomerate.The results show that the paleoflow direction is from northwest to southwest,and the paleocurrent data manifest a single-peak style in a rose diagram.The average paleoflow direction in the Qian’an region is 265°.The basal conglomerate is of littoral facies,and the sediments of conglomerates are mainly sourced from Shanhaiguan.展开更多
文摘国际地层委员会将中元古界底界界线年龄定为1600 Ma,1600～1400 Ma为Calymmian（盖层系）,表示全球地台盖层形成时期.华北地台基底固结时间为1800Ma,固结后即进入伸展裂解作用时期,首先是山西吕梁山区、晋南中条山、豫西熊耳山区裂解发展成三叉裂陷槽（Aulacogen）.吕梁山区小两岭组火山岩形成年龄有1778±20 Ma（SHRIMP U Pb锆石）及1779±20 Ma（LA ICP MS U Pb锆石）两个数值;豫西熊耳群顶部马家河组和中部鸡蛋坪组及下部许山组火山岩年龄分别为1776±20 Ma、1791±20 Ma和1783±13 Ma（SHRIMP U Pb锆石）,1776～1800Ma为火山岩的形成年龄;将1800Ma作为小两岭组与熊耳群两个火山岩组的底界年龄应当是合理的.吕梁山区的汉高山群为碎屑岩夹火山岩,代表吕梁陕豫三叉裂陷槽北支中的快速充填,与小两岭组为同时期沉积.汉高山群、大古石组（熊耳群底部沉积岩）为1800Ma裂解开始的盖层沉积,小两岭组火山岩、相关的辉绿岩墙及熊耳群火山岩均为裂解时期的岩浆作用产物.北京密云环斑花岗岩侵位时间为1700Ma,代表燕山太行山裂陷槽裂解的起始时间也即燕山地区长城系常州沟组底界年龄.北京密云地区环斑花岗岩风化壳上覆常州沟组年龄可确定为1650Ma,它不应被看作常州沟组最低层位的年龄,而是裂陷槽裂解后密云地区开始接受沉积的年龄,1700Ma、1650Ma代表常州沟组在不同地区的底界年龄,但均不等于长城系或中元古界的底界年龄.1600Ma为高于庄组底界年龄,即长城系与蓟县系的界线年龄,也是国际地层委员会中元古界的底界年龄.1600 Ma代表燕山太行山裂陷槽闭合的年龄,也是华北地台始自1800Ma伸展裂解作用的最终结束时期.1600Ma是新的陆表海盆地发展的起始时间,是重要的华北地台构造转换的时期.因此,1800与1600 Ma代表华北地台重大地质构造事件的年龄,具大区域构造意义,依据对前寒�
文摘In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (~1 600-1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely shaped like Chuaria Shouhsiennia (Ellipsophyta) and Tawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namely Chuaria- and Shouhsienia-llke forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply a very important basis in histology to determine the
基金Supported by the Geological Relic Protection Project of Ministry of Finance and Ministry of Land and Resources of China
文摘The paleoflow direction of the basal conglomerate of the Changzhougou formation is obtained by the paleocurrent analysis of certain sedimentary structures,and the ancient sedimentary environment of the Qian’an Region is determined by observing the psephicity and gradation of gravel in conglomerate.The results show that the paleoflow direction is from northwest to southwest,and the paleocurrent data manifest a single-peak style in a rose diagram.The average paleoflow direction in the Qian’an region is 265°.The basal conglomerate is of littoral facies,and the sediments of conglomerates are mainly sourced from Shanhaiguan.
