本文選題：漠河盆地 + 二十二站組��； 參考：《地球科學(xué)》2017年01期

【摘要】：大興安嶺北部的漠河盆地廣泛發(fā)育中生界二十二站組砂巖,其形成時(shí)代一直備受爭(zhēng)議.首次利用碎屑鋯石LA-ICP-MS U-Pb法測(cè)年對(duì)其形成時(shí)代作出較為精確的限定,并結(jié)合地球化學(xué)特征對(duì)其物源區(qū)及大地構(gòu)造背景進(jìn)行了探討.研究結(jié)果表明,二十二站組砂巖碎屑物磨圓度較低、分選差,表現(xiàn)出源區(qū)相對(duì)不穩(wěn)定,快速剝蝕、搬運(yùn)及沉積的特征.鋯石顆粒粗大,具有清晰的震蕩環(huán)帶,Th/U值為0.35~1.07,為典型的巖漿鋯石.測(cè)年結(jié)果顯示,90個(gè)測(cè)點(diǎn)年齡主要分布在3個(gè)群落:152~170Ma,峰值年齡約為158Ma,這一年齡區(qū)間揭示了二十二站組沉積成巖的下限為晚侏羅世;179~193Ma,峰值年齡約為190Ma;205~214Ma,峰值年齡約為210Ma.3個(gè)年齡峰值為蒙古-鄂霍茨克洋演化過程中一系列巖漿活動(dòng)的地質(zhì)記錄,其中210Ma與190Ma峰值年齡與盆地南緣額爾古納地塊晚三疊世、早侏羅世的巖漿事件相吻合,而158Ma峰值年齡則對(duì)應(yīng)于盆地北緣晚侏羅世的巖漿事件.主、微量元素構(gòu)造判別圖解揭示其物源區(qū)具有活動(dòng)大陸邊緣的特征,同時(shí)鋯石定年數(shù)據(jù)顯示其沒有任何前中生代的碎屑物,暗示了該3期巖漿巖均形成于額爾古納地塊北緣的中生代活動(dòng)大陸邊緣環(huán)境,并為二十二站組的形成提供了主要碎屑物質(zhì).由此說明,二十二站組砂巖形成于晚侏羅世蒙古-鄂霍茨克洋閉合后的造山過程中,漠河盆地南北兩側(cè)物源區(qū)快速剝蝕、快速搬運(yùn)與快速沉積的環(huán)境.
[Abstract]:The Mohe basin in the northern part of Daxinganling has been widely developed in the Mesozoic 22 formation sandstone, and its formation time has been controversial.For the first time, the LA-ICP-MS U-Pb dating of detrital zircon is used to define the age of its formation, and its provenance and tectonic background are discussed in the light of geochemical characteristics.The results show that the sandstones of 22 station have low grinding roundness and poor sorting, showing the characteristics of relatively unstable source area, rapid denudation, transport and deposition.The zircon grain is coarse, and the Th-P U value of the zigzag is 0.35 ~ 1.07, which is a typical magmatic zircon.The dating results show that the age of 90 sites is mainly distributed in 3 communities at 1522 ~ 170 Ma, and the peak age is about 158 Ma. This age range reveals that the lower limit of sedimentary diagenesis in the 22 station formation is late Jurassic ~ (179) ~ (19) Ma, the peak age is about 190 Ma ~ (205) ~ (21) Ma, and the peak age is about 210Ma.3.The peak age is a geological record of a series of magmatic activities during the evolution of the Mongolia-Okhotsk Ocean.The peak ages of 210Ma and 190Ma are consistent with the late Triassic and early Jurassic magmatic events of the Erguna block in the southern margin of the basin, while the 158Ma peak age corresponds to the late Jurassic magmatic events in the northern margin of the basin.The tectonic discriminant diagram of main and trace elements reveals that the provenance region has the characteristics of active continental margin, and the zircon dating data show that there is no pre-Mesozoic clastic material.It is suggested that the magmatic rocks of the three periods were formed in the Mesozoic active continental margin environment of the northern margin of the Erguna block and provided the main clastic material for the formation of the 22 station formation.It is concluded that the sandstones of formation 22 were formed in the late Jurassic Mongolia-Okhotsk ocean closed orogenic process, Mohe basin north and south two sides of the source areas rapid denudation, rapid transport and rapid deposition environment.
【作者單位】： 吉林大學(xué)地球科學(xué)學(xué)院;山東科技大學(xué)地球科學(xué)與工程學(xué)院;武警黃金第一支隊(duì);
【基金】：中國(guó)地質(zhì)調(diào)查局項(xiàng)目(No.1212011085485) 國(guó)家自然科學(xué)基金項(xiàng)目(No.41272093)
【分類號(hào)】：P588.212.3

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