干旱区生态环境知识资源中心(Arid): 准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组云质岩沉积环境及白云石成因探讨

Arid

	准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组云质岩沉积环境及白云石成因探讨
其他题名	Sedimentary environment and formation mechanisim of dolomitic rocks in the Middle Permian Lucaogou Formation, Jimusar Depression, Junggar Basin
	张帅 1; 柳益群 1; 焦鑫 1; 周鼎武 2; 张旭 1; 陆申童 1; 周宁超 3
来源期刊	古地理学报
ISSN	1671-1505
出版年	2018
卷号	20 期号:1 页码:33-48
中文摘要	准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组发育一套陆内裂谷背景下,由粉砂级-泥级陆源碎屑、凝灰碎屑、碳酸盐及热液矿物组成的湖相细粒云质岩。本研究以云质岩为研究对象,通过岩石学、矿物学及地球化学研究探讨其形成环境和白云石形成机理。云质岩岩矿特征和主、微量元素特征表明,在中二叠世为处于干旱气候的浅水咸化湖盆,区域火山活动强烈,湖盆内幔源热液活动发育。云质岩中的白云石主要呈自形-半自形的微粉晶颗粒,形成细纹层或与其他组分混合,局部可见自形-半自形的细晶白云石,微粉晶白云石为低有序度白云石(0.46),成分均匀,被纹层包绕,细晶白云石交代残留结构发育,为成岩交代的产物;两类白云石均富锶贫镁,细晶白云石较微粉晶白云石更富铁和锰。微粉晶白云石具有较低的delta~(18)O_(PDB)(平均为-4.72),基于白云石的形成流体由湖水和幔源热液混合的假设,所计算得到的形成温度介于54.61~186.46 ℃之间;delta~(13)C_(PDB)偏高(平均为8.79),推测其与芦草沟组高的有机质埋藏量及产甲烷古菌的代谢活动有关。微粉晶白云石为同生期-准同生期沉淀或交代的原白云石,其Mg~(2+)来自于咸化湖水、凝灰碎屑和幔源热液,热液带来的高温和产甲烷古菌的代谢活动打破了白云石形成的动力学屏障。
英文摘要	The Middle Permian Lucaogou Formation of Jimusar Depression,Junggar Basin is characterized by lacustrine fine-grained dolomitic sediments,which are composed of silt-sized to mud-sized terrigenous clasts,tuff clasts,carbonate and hydrothermal minerals. This paper is aimed to understand the sedimentary environment and formation mechanism of dolomitic rocks by studying their petrological,mineralogical and geochemical features. Petrological-mineralogical and major and trace element characteristics of the dolomitic rocks suggest the study area was a shallow salty lake formed under an arid climate during the Middle Permian,and was characterized by intense regional volcanism and active mantle-derived hydrothermal in the basin. The dolomites in the dolomitic rocks mainly present as euhedral-subhedral micritic crystals,forming fine lamination or mixing with other compositions,while fine-crystalline dolomites can only be found occasionally. The micritic dolomites,with low order degrees(0.46)and homogeneous compositions,are usually surrounded by laminations. The fine-crystalline dolomites are featured by well-developed metasomatic relict texture and thereby should be the product of diagenesis. Both two kinds of dolomites have high strontium and low magnesium contents,while fine-crystalline dolomites have higher contents of iron and manganese than that of micritic dolomites. The micritic dolomites have a low delta~(18)O_(PDB)(av.-4.72). The forming temperature,54.61℃ to 186.46℃,is calculated from the delta~(18)O_(PDB) by assuming that the fluid was the mixture of lake water and mantle-derived hydrothermal fluid. The high delta~(13)C_(PDB)(av. 8.79)of micritic dolomites might be resulted from the gigantic buried organic matter of Lucaogou Formation and metabolic activities of methanogens. In conclusion,the micritic dolomites are contemporaneous-penecontemporaneous protodolomite. Magnesium ion was supplied by the salty lake water,tuff materials as well as mantle-dervied hydrothermal fluid. The dynamic barrier of dolomite formation was broken by the high temperature brought from hydrothermal fluid and the metabolic activities of methanogens.
中文关键词	白云石 ; 成因 ; 幔源热液 ; 芦草沟组 ; 吉木萨尔凹陷 ; 准噶尔盆地
英文关键词	dolomite origin mantle-derived hydrothermal fluid Lucaogou Formation Jimusar Depression Junggar Basin
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOLOGY
WOS研究方向	Geology
CSCD记录号	CSCD:6178479
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/237771
作者单位	1.西北大学地质学系, 西北大学大陆动力学国家重点实验室, 西安, 陕西 710069, 中国; 2.山东科技大学地质科学与地质工程学院, 青岛, 山东 266510, 中国; 3.中国地质调查局西安地质调查中心, 西安, 陕西 710069, 中国
推荐引用方式 GB/T 7714	张帅,柳益群,焦鑫,等. 准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组云质岩沉积环境及白云石成因探讨[J],2018,20(1):33-48.
APA	张帅.,柳益群.,焦鑫.,周鼎武.,张旭.,...&周宁超.(2018).准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组云质岩沉积环境及白云石成因探讨.古地理学报,20(1),33-48.
MLA	张帅,et al."准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组云质岩沉积环境及白云石成因探讨".古地理学报 20.1(2018):33-48.