【摘要】：采用LA-ICP-MS碎屑鋯石原位微區(qū)測(cè)年方法,對(duì)鄂爾多斯盆地南部黃陵地區(qū)及彬縣地區(qū)中侏羅統(tǒng)直羅組砂巖進(jìn)行了碎屑鋯石U-Pb年齡分布特征研究,統(tǒng)計(jì)和對(duì)比盆地周緣巖體的同位素年代學(xué)結(jié)果,結(jié)合盆地南部直羅組地層典型露頭實(shí)測(cè)古水流數(shù)據(jù),綜合研究了盆地南部直羅組沉積物源。結(jié)果表明:(1)黃陵地區(qū)直羅組樣品總體呈169~438 Ma、1 435~2 083 Ma、2 300~2 767 Ma三個(gè)年齡組,對(duì)應(yīng)峰值分別為274 Ma、1 851 Ma和2 366 Ma。彬縣地區(qū)直羅組樣品總體呈213~485 Ma、802~974 Ma、1 633~1 894 Ma和2 143~2 739 Ma 4個(gè)年齡組,對(duì)應(yīng)峰值分別為430Ma、450Ma、1 720Ma和2 254Ma。(2)黃陵地區(qū)直羅組地層物源主體來自西北部阿拉善地塊的中酸性侵入巖及變質(zhì)巖。彬縣地區(qū)直羅組地層物源主體來自西部的北、中祁連造山帶,源巖為中酸性侵入巖、基性侵入巖及變質(zhì)巖,同時(shí)存在火山巖、碎屑巖及變質(zhì)碎屑巖的部分貢獻(xiàn)。(3)盆地南部直羅組下段地層各典型露頭古水流優(yōu)勢(shì)方向集中于110°~140°,表明古流向以向東和東南為主,即該時(shí)期物源主要來自盆地西、西北方向,這與碎屑鋯石年代學(xué)對(duì)比所指示的物源區(qū)相一致,這些物源分析結(jié)果對(duì)于進(jìn)一步認(rèn)識(shí)侏羅紀(jì)時(shí)期盆地原型及古地理格局具有較重要的參考價(jià)值。
[Abstract]:LA-ICP-MS in situ microdating of clastic zircons was used to study the age distribution of clastic zircons from the middle Jurassic Zhiluo formation sandstone in the Huangling area and Binxian area of the southern Ordos basin, and the age distribution characteristics of the clastic zircon were studied. Based on the isotopic chronological results of the peripheral rock masses of the basin and the paleocurrent data measured at the typical outcrops of the Zhiluo formation in the southern part of the basin, the sediment sources of the Zhiluo formation in the southern part of the basin are comprehensively studied. The results showed that: (1) in Huangling area, the corresponding peak values were 274 Ma,1 851 Ma and 2 366 Ma., respectively, in three age groups: 169 / 438 Ma,1 435 / 2083 Ma,2 300 / 2 767 Ma, respectively, and the corresponding peak values of the samples were 274 Ma,1 851 Ma and 2 366 Ma., respectively. The corresponding peak values were 430 Ma and 450 Ma, respectively, in four age groups of 213,485 Ma,802~974 Ma,1 633, 1,894 Ma and 2 143, 2,739 Ma in Binxian district, respectively, and the corresponding peak values were 430Ma and 450Ma, respectively, and the corresponding peaks were 430Ma and 450Ma, respectively. 1 720Ma and 2254 Ma. (2) the provenance of the Zhiluo formation in Huangling area is mainly from the intermediate-acid intrusive rocks and metamorphic rocks of the Alashan block in northwest China. The stratigraphic provenance of Zhiluo formation in Binxian area is mainly from the northern and middle Qilian orogenic belts in the west. The source rocks are intermediate acid intrusive rocks, basic intrusive rocks and metamorphic rocks, and volcanic rocks exist at the same time. Some contributions of clastic rocks and metamorphic clastic rocks. (3) the dominant directions of typical outcrop paleocurrent in the lower strata of the Zhiluo formation in the southern part of the basin are concentrated in the range of 110 擄~ 140 擄, indicating that the paleo-direction is mainly eastward and southeastward, that is, the provenance of this period is mainly from the west of the basin. In the northwest direction, this is consistent with the provenance area indicated by the chronological comparison of clastic zircon. These provenance analysis results have important reference value for further understanding the prototype and palaeogeographic pattern of Jurassic basin.
【作者單位】： 大陸動(dòng)力學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室;西北大學(xué)地質(zhì)學(xué)系;陜西延長(zhǎng)石油(集團(tuán))油氣勘探公司延長(zhǎng)氣田采氣一廠;
【基金】：國(guó)家自然科學(xué)重點(diǎn)基金項(xiàng)目(41330315) 中國(guó)地質(zhì)調(diào)查局工作項(xiàng)目(12120114009201) 西北大學(xué)大陸動(dòng)力學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室科學(xué)技術(shù)部專項(xiàng)經(jīng)費(fèi)資助項(xiàng)目
【分類號(hào)】：P534.52;P597.3
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本文編號(hào)：2452177