Geochemistry of the dolomitic rocks from the Permian Lucaogou Formation in the Jimusar depression, Junggar Basin, Xinjiang
-
摘要: 研究区芦草沟组云质岩主要包含泥晶白云岩、凝灰质白云岩和白云质凝灰岩等类型，对准噶尔盆地吉木萨尔凹陷二叠系芦草沟组广泛发育的云质岩进行详细的地球化学研究，分析了芦草沟组云质岩的物质来源和沉积环境。云质岩的c（Mg）/c（Ca）比值0.03~1.44，磷含量262×10-6~17283×10-6，Th/U比值0.58~2.00，V/（V+Ni）比值0.60~0.89，V/Cr比值1.25~6.38，Sr/Ba比值0.55~8.25，反映了云质岩形成于生物繁盛的还原性咸水湖泊环境，Mg离子主要来源于深部岩浆热液。碳、氧同位素研究反映芦草沟组主要形成于温度较高的咸水环境中，且由早至晚芦草沟组沉积期具有温度升高而盐度降低的趋势。温度的升高引起的蒸发量增大并没有带来湖水盐度的增加，这种碳酸盐碳、氧同位素反向变化关系可能由于芦草沟组沉积后期不断有外源淡水的输入造成。Abstract: The dolomitic rocks from the Permian Lucaogou Formation in the Jimusar depression, Junggar Basin, Xinjiang mainly consist of micritic dolostone, tuffaceous dolostone and dolomitic tuff. In the present paper, the highlights are concentrated in the geochemical signatures, provenance and sedimentary environment of the dolomitic rocks widespread in the study area. These dolomitic rocks have P contents ranging from 262×10-6 to 17283×10-6 (with an average of 427.70×10-6, very close to that of North America Shale Composite), c(Mg)/c(Ca) ratios of 0.03-1.44, Th/U ratios of 0.58-2.00, V/(V+Ni) ratios of 0.60-0.89, V/Cr ratios of 1.25-6.38, V/Sc ratios of 3.65-16.19, and Sr/Ba ratios of 0.55-8.25. The analytical results outlined above suggest that the dolomitic rocks in the Lucaogou Formation were formed in the salt-water reducing lake environments with abundant organisms, and magnesium ions are inferred mainly to be originated from deep-seated magmatic hydrothermal solutions. The carbon and oxygen isotopic data also demonstrate that the Lucaogou Formation was laid down in the continental salt-water lake environments with higher temperatures. There is a tendency of gradual increase of temperatures and gradual decrease of salinities from the early to later stages of the deposition of the Lucaogou Formation. However, there is no evidence in favour of salinity increase in the highly-evaporated lake water due to temperature increase. The abnormal changes of the above-mentioned palaeotemperatures and palaeosalinities based on carbon and oxygen isotopic data of the carbonate minerals may be caused by the input processes of allochthonous fresh water in the later stages of the deposition of the Lucaogou Formation.
-
Keywords:
- Jimusar depression /
- Lucaogou Formation /
- dolostone /
- geochemistry
-
-
[1] 蒋宜勤,柳益群,杨召,等. 准噶尔盆地吉木萨尔凹陷凝灰岩型致密油特征与成因[J]. 石油勘探与开发,2015,42(6):741-749. [2] 葸克来,操应长,朱如凯,等. 吉木萨尔凹陷二叠系芦草沟组致密油储层岩石类型及特征[J]. 石油学报,2015,36(12):1495-1507. [3] 匡立春,胡文瑄,王旭龙,等. 吉木萨尔凹陷芦草沟组致密油储层初步研究:岩性与孔隙特征分析[J]. 地质学报,2013,19(3):529-535. [4] 宋永,周路,郭旭光,等. 准噶尔盆地吉木萨尔凹陷芦草沟组湖相云质致密油储层特征与分布规律[J]. 岩石学报,2017,33(4):1159-1170. [5] 邱振,吴晓智,唐勇,等. 准噶尔盆地吉木萨尔凹陷二叠系芦草沟组致密油资源评价[J]. 天然气地球科学,2016,27(9):1688-1698. [6] 曲长胜,邱隆伟,杨勇强,等. 吉木萨尔凹陷芦草沟组碳酸盐岩碳氧同位素特征及其古湖泊学意义[J]. 地质学报,2017,91(3):605-616. [7] 李红南,毛新军,胡广文,等. 准噶尔盆地吉木萨尔凹陷芦草沟组致密油储层特征及产能预测研究[J]. 石油天然气学报,2014,36(10):40-44. [8] 王成云,匡立春,高岗,等. 吉木萨尔凹陷芦草沟组泥质岩类生烃潜力差异性分析[J]. 沉积学报,2014,32(2):385-390. [9] 鲁新川,张顺存,史基安. 准噶尔盆地西北缘乌尔禾-风城地区二叠系风城组白云岩地球化学特征及成因分析[J]. 兰州大学学报(自然科学版),2012,48(6):8-20. [10] Kelley D S,Karson J A, Blackman D K. An off-axis hydrothermal vent field near the mid-Atlantic Ridge at 30°N[J]. Nature, 2001, 412:145-149.
[11] 高福红,高红梅,赵磊. 火山喷发活动对烃源岩的影响:以拉布达林盆地上库力组为例[J]. 岩石学报,2009,25(10):2671-2678. [12] 郝英,王定一,冯有良,等. 胜利油田火山岩中的流体包裹体成分及其意义[J]. 地球化学,1996,25(5):468-474. [13] 郝英,王定一,廖永胜,等. 胜利油田火山岩类、盆地演化及其CO2-Au成藏成矿效应[J]. 地质科学,2001,36(4):454-464. [14] Haskin M A, Haskin L A. Rare earths in European shales:A redetermination[J]. Science, 1996, 154:507-509.
[15] Wignall P B, Twitchett R J. Oceanic anoxia and the end Permian mass extinction[J]. Science, 1996, 272:1155-1158.
[16] Kimura H, Watanabe Y. Ocean anoxia at the Precambrian-Cambrian boundary[J]. Geology, 2001, 29:995-998.
[17] Calvert S E, Pedersen T F. Geochemistry of recent oxic and anoxic marine sediments:implications for the geologic record[J]. Marine Geology,1993, 113:67-88.
[18] Emerson S R,Huested S S. Ocean anoxia and the concentrations of molybdenum and vanadium in seawater[J]. Marine Chemistry, 1991, 177-196.
[19] 孙镇城,杨藩,张枝焕,等. 中国新生代咸化湖泊沉积环境与油气生成[M]. 北京:石油工业出版社,1997.133-254. [20] 宋明水. 东营凹陷南斜坡沙四段沉积环境的地球化学特征[J]. 矿物岩石,2005,25(1):67-73. [21] Derry L A,Brasier M D, Corfield R M, et al. Sr and C isotopes in Lower Cambrian carbonates from the Siberian craton:A paleoenvironmental record during the ‘Cambrian explosion’[J]. Earth and Planetary Science Letters, 1994,128(3-4):671-681.
[22] Kaufman A J, Jacobsen S B, Knoll A H. The Vendian record of Sr and C isoyopic variations in seawater:Implications for tectonic and paleoclimate[J]. Earth and Planetary Science Letters, 1993, 120(3-4):409-430.
[23] Qing H,Veizer J. Oxygen and Carbon isotopic composition of Ordovician brachiopods:Implication for coeval seawater[J]. Geochimica et Cosmochimica Acta, 1994, 58(20):4429-4442.
计量
- 文章访问数: 419
- HTML全文浏览量: 0
- PDF下载量: 552
下载:
