CAJ | 학술논문

铁克里克山位于塔里木地块西南缘,被认为是塔里木板块的褶皱基底.其前寒武纪地层主要由前人认为的"古元古代埃连卡特岩群"和"长城纪塞拉加兹塔格岩群"组成,保存有塔里木盆地前寒武纪地壳形成和演化的重要信息.LA-ICP-MS锆石微区原位定年结果显示,埃连卡特岩群绿泥方解石石英片岩中锆石的~(206)Pb/~(238)U年龄值主体集中于736～810 Ma,780 Ma 年龄数据构成峰值；塞拉加兹塔格岩群变凝灰岩中锆石的~(206)Pb/~(238)U年龄值介于779～792 Ma之间,其加权平均年龄为787±1 Ma.这些测点相对应的锆石CL图像、U、Th含量和Th/U比值具有岩浆锆石特征,同时,这些峰值年龄具有较好的谐和性,可以作为相应地层的最大沉积时代,指示其形成于新元古代南华纪.通过对铁克里克山地区的埃连卡特岩群和塞拉加兹塔格岩群的物质组成、地球化学特征和新的精确年代学数据对比分析,可以推测二者地层可能为同一地层,其形成时代下限应为新元古代早期,为塔里木板块南缘前寒武纪基底存在Rodinia 超大陆裂解事件的物质记录.塞拉加兹塔格岩群中锆石Hf 同位素分析表明,787 Ma 左右的锆石颗粒具有负的εHf(t)值和约1900 Ma 的两阶段Hf 模式年龄, 说明塞拉加兹塔格岩群主体是由古元古代的地壳物质重熔后再沉积形成的,为古老地壳的再造.约1986 Ma的捕获锆石εHf(t)值变化于-2.3～5.0之间, 两阶段模式年龄介于2241～2813 Ma,具有正和负的εHf(t)值, 指示这些锆石的母岩中存在古元古代的新生地壳和太古宙地壳再造.
철극리극산위우탑리목지괴서남연,피인위시탑리목판괴적습추기저.기전한무기지층주요유전인인위적"고원고대애련잡특암군"화"장성기새랍가자탑격암군"조성,보존유탑리목분지전한무기지각형성화연화적중요신식.LA-ICP-MS고석미구원위정년결과현시,애련잡특암군록니방해석석영편암중고석적~(206)Pb/~(238)U년령치주체집중우736～810 Ma,780 Ma 년령수거구성봉치；새랍가자탑격암군변응회암중고석적~(206)Pb/~(238)U년령치개우779～792 Ma지간,기가권평균년령위787±1 Ma.저사측점상대응적고석CL도상、U、Th함량화Th/U비치구유암장고석특정,동시,저사봉치년령구유교호적해화성,가이작위상응지층적최대침적시대,지시기형성우신원고대남화기.통과대철극리극산지구적애련잡특암군화새랍가자탑격암군적물질조성、지구화학특정화신적정학년대학수거대비분석,가이추측이자지층가능위동일지층,기형성시대하한응위신원고대조기,위탑리목판괴남연전한무기기저존재Rodinia 초대륙렬해사건적물질기록.새랍가자탑격암군중고석Hf 동위소분석표명,787 Ma 좌우적고석과립구유부적εHf(t)치화약1900 Ma 적량계단Hf 모식년령, 설명새랍가자탑격암군주체시유고원고대적지각물질중용후재침적형성적,위고로지각적재조.약1986 Ma적포획고석εHf(t)치변화우-2.3～5.0지간, 량계단모식년령개우2241～2813 Ma,구유정화부적εHf(t)치, 지시저사고석적모암중존재고원고대적신생지각화태고주지각재조.
Tiekelike Mountain is located at the sourthwestern margin of the Tarim block and has been regarded as a folded basement. Precrambrain sequence consisting of Ailiankate Group and Sailajiazitage Group contains important signatures of the Precrambrain and evolution of Tarim basin, but were previously considered to be Paleoproterozoic-Mesoproterozoic. Zircon U Pb LA-ICP-MS dating of chlorite quartz schist and tuff from the Ailiankate Group and Sailajiazitage Group have yielded crystallisation age peaks at 780 and 787 Ma, respectively. These data indicate the Ailiankate and Sailajiazitage groups are Neoproterozoic succession deposited at ca. 780～800 Ma. Those strata are all temporally equivalent and are likely parts of a single widespread succession and reflect a rifting process related to break-up of Rodinia supercontinent. In situ zircon Hf isotopic data from the Sailajiazitage Group show that some zircons have Hf model ages up to 2241～2813 Ma, suggesting an ancient crustal growth and reworking. The Hf isotopic data also indicate that the ～787 Ma zircons have ～1900 Ma Hf model ages, suggesting derivations from recycled Paleoproterozoic material.