西秦岭卓尼地区晚三叠世卡尼期海底扇盆内型与盆外型重力流沉积过程及其源-汇意义

最新深水沉积学研究表明，盆内型与盆外型重力流是形成海底扇的两种主要供源形式。这两者实质是由多种性质的重力流流体沉积而成，反映了复杂的沉积过程。其沉积结构不仅控制沉积砂体类型，而且影响深水储层空间展布。由于供源形式的差异，盆内型与盆外型重力流碎屑信号对母岩信息和环境信号的响应存在显著差异，特别是在中短期时间尺度（10⁴-10⁵年）下有较好的体现。针对重力流沉积过程及其碎屑信号响应的科学问题，本项目以过程沉积学及源-汇系统理论为指导，对西秦岭卓尼地区晚三叠世卡尼期海底扇露头进行精细沉积学解剖及重力流系统分类学研究，探讨盆内型与盆外型重力流的流体类型及沉积过程差异性特征，建立相应的沉积模式；利用碎屑锆石物源定量示踪及反演解析的方法，将海底扇中短期碎屑信号变化与重力流供源方式联系起来，以建立晚三叠世东特提斯海底扇盆内型与盆外型重力流碎屑信号传输的定量模型，为深水油气资源高效勘探开发提供理论基础。

According to the latest studies on deep-water sedimentology, intra-basinal and extra-basinal gravity flows are two major sediment supply styles in the formation of submarine fan. Actually, both of them contain gravity flows with various fluid properties, which are characterized by complicated sedimentary processes. Their sedimentary architectures control not only the types of depositional sand-bodies but also the spatial distribution of deep-water reservoirs. Due to the difference of the sediment supply styles, the detrital signals from intra-basinal and extra-basinal gravity flow deposits differ significantly in their responses to parent rock information and environmental signal, which is particularly well manifested within an intermediate to short time scale (10⁴-10⁵ yrs). In view of the scientific issues concerning sedimentary processes of gravity flows and their responses in detrital signals, guided by process sedimentology and principle of source-to-sink system, the study aims to make a detailed sedimentological anatomy and systematic classification study of gravity flows based on the late Triassic Carnian submarine fan outcrop in the Zhuoni area of the Western Qinling, investigate differential characteristics of fluid types and sedimentary processes of intra-basinal and extra-basinal gravity flows, and build the corresponding depositional models. Quantitative provenance tracing analysis and unmixing of detrital zircon age distributions through the inversion method will be applied here to linking the intermediate- to short-time-scale variation of detrital signals in the submarine fan to the sediment supply styles of gravity flows, and to reconstructing a quantitative model for the detrital signal propagation of intra-basinal and extra-basinal gravity flows of the late Triassic submarine fan in the eastern Tethys region. This study will also provide a theoretical basis for effective exploration and production of deep-water oil and gas resources.