图1 峨眉山大火成岩省及研究区基本信息 a—峨眉山大火成岩省露头区(土黄色块表示)、带域划分(黑色虚线)以及研究区所在范围(黄色区块);b—四川盆地内研究区所在范围及探井相对位置。

Fig.1 Overview of the Emeishan Large Igneous Province (ELIP) a—Geographic distribution of the ELIP outcrop area (depicted in brown shades), its zonation delineated by black dashed circles, and the specific study area highlighted within a light yellow rectangle. b—Detailed depiction of the study area within the Sichuan Basin, with well sites denoted by yellow dots. Yellow dots represent well sites.

图2 本文所采用的火山碎屑岩岩性识别鉴定标准简要图(c图据文献[25]) a—火山碎屑的成分分类;b—火山碎屑的粒径分类;c—基于粒径比例的火山碎屑岩分类三角图;d—成因分类命名。在具体识别出岩性指示标志时,可进一步用精确的成因分类法来命名之。

Fig.2 Fundamentals of mafic volcaniclastic rock classification: a—Compositional classification of volcaniclasts; b—Size-based classification of volcaniclasts; c—Size-based classification of mafic volcaniclastic rocks(adapted from [25]); d—Genetic terminology for mafic volcaniclastic rocks.

图3 (a) 火山岩优势储集层段的地层岩性及其测井响应;(b-f)标注深度段的具体成像测井特征

Fig.3 (a) Well log of the sections of well-developed volcanic reservoir; (b-f) Image logging with corresponding depth

图4 熔结凝灰岩现象图版 a,b—YT1井熔结凝灰岩岩心现象,暗绿色近平行条带即火焰石结构;c,d—YT1井熔结凝灰岩的镜下现象,熔结条带近平行分布于绿泥石化的基质中;e—TF1井熔结凝灰岩岩心现象,火焰石结构与饱受烘烤而大理岩化的外源灰岩角砾分布于绿泥石化的绿色基质中;f—TF1井熔结凝灰岩镜下现象,部分长石晶屑被流动状的熔结浆屑焊结;g—TF1井熔结凝灰岩溶蚀孔内发育的三世代胶结物:最外侧雾心亮边的短柱状晶体为钠长石,往里为第二世代不透明沥青,中心充填它形方解石(茜素红染色);h—TF2井熔结凝灰岩岩心现象;i,j—TF2井熔结凝灰岩镜下现象,注意浆屑几乎被完全溶蚀产生的铸膜溶蚀孔(蓝色)以及不受溶蚀影响的灰岩角砾(图i中板状和图j中右下角角砾)和细晶方解石胶结物;k—TF102井熔结凝灰岩岩心;l—TF102井熔结凝灰岩中发育巨大溶蚀孔洞,并充填早期沥青和晚期方解石。

Fig.4 Observations of ignimbrites YT1 ignimbrites: a,b—Display darker green fiammes; c,d—Microscopic view shows eutaxitic texture. TF1 ignimbrites: e—Contain recrystallized limestone blocks mixed with fiammes and tephra matrix; f—Microscopic view reveals plagioclase crystal shards sticking together due to welding magma shards. Cement generations in dissolved vugs: g—Progress from albite to bitumen to calcite. TF2 ignimbrites: h—Observed. Microscopic view of TF2 ignimbrites: i,j—Depicts dissolving molds of juvenile clasts (blue colored), with limestone lithic blocks and micrite matrix showing no interference. TF102 ignimbrites: k—Observed. Development of significant vugs filled with bitumen and calcite in TF102 ignimbrites: l—A huge dissolved vug developed in the ignimbrite in TF102, filling with earlier-stage bitumen and later-stage calcite crystals.

图5 自碎裂角砾岩现象图版 a,b—TF8井自碎裂角砾岩岩心现象。请注意该岩性和熔结凝灰岩的关键区分方式:角砾之间紧密堆积,且角砾边界呈现可拼合特质,不熔结,维持刚性,内部完全不发育任何外源角砾。图a为第一回次,受方解石单世代胶结,其对应镜下现象为c;图b为第三回次,受钠长石-沥青-方解石三世代胶结,对应镜下d。c,d—TF8井自碎裂角砾岩的镜下现象。棱角分明的浆屑呈现刚性、不熔结特质;请注意图d中开放溶蚀孔发育的位置(浆屑内部,蓝色铸体),而原生时开放的角砾间孔隙则已经被胶结物堵塞完全。e,f—TF102井上覆于熔结凝灰岩层段的自碎裂角砾岩。

Fig.5 Plate of autoclastic breccia a,b—Autoclastic breccia in TF8. Note the distinctive features of autoclastic breccia compared to ignimbrites: the clastic-supporting framework with jigsaw-fitted boundaries, unwelded texture, and absence of epiclastic blocks. c,d—Microscopic views of autoclastic breccia in TF8 corresponding to (a) and (b), respectively. Please observe the location where pore spaces are developed within the clasts, while the initial inter-clastic spaces are completely filled. e,f—Autoclastic breccia in TF102.

图6 溅积集块岩现象图版 a,b—TF1井溅积集块岩的宏观岩心照片,白色角砾为烘烤重结晶而大理岩化的灰岩角砾,周围基质为致密焊结压实的溅积浆屑,图b中显示巨大的火山弹(纺锤状)的切面;c,d—为溅积集块岩的镜下现象,流动状的火山碎屑堆积体之间的原生开放孔隙同样被钠长石-沥青-方解石三世代胶结。

Fig.6 Plate of spattering agglomerates a,b—Spattering agglomerates in TF1, featuring white lithic blocks composed of recrystallized limestones. b—Section of a fusiform bomb. c,d—Microscopic views of spattering agglomerates, showing inter-clast spaces filled with albite, bitumen, and calcite.

图7 三类岩性系列的喷发成因机制示意图 a—陆上溢气式喷发产生火山碎屑流进而形成熔结凝灰岩发育的过程。岩浆房内白色圆圈为溢出的挥发分,浅灰色块体为围岩(灰岩)岩块。暗色块体为火山机构早期堆积物质。细点阵为火山碎屑流喷发时伴生的灰云。b—裂隙式喷发溢流熔岩自碎裂化过程。若岩浆核心亦最终停止运移,则核心部位往往形成致密玄武岩,其前端则过渡为富裂缝玄武岩,直至自碎裂角砾岩。c—岩浆上涌过程中若挥发分溢出量低,岩浆碎解不明显,导致最终喷发时浆屑块体巨大,往往以火山弹形式出现,以较低的能量沿火口近距离抛射,在近源溅积,构成火山弹堆积层。

Fig.7 Schematic diagram of the eruptive genesis mechanisms of three types of lithological series a—Eruption by on-land gas overflowing generates volcanic pyroclastic flows, leading to the formation of welded tuff. The white circles in the magma chamber represent overflowing volatile components, the light gray blocks are country rock (limestone) fragments, and the dark blocks are early volcanic materials. The fine dots represent ash clouds accompanying the eruption of volcanic pyroclastic flows. b—Eruption through fissures results in the overflow of molten lava and its fracturing process. If the magma core eventually stops moving, the core often forms dense basalt, transitioning to fissure-rich basalt at the front, and eventually to angular breccia. c—During the magma upwelling process, if the amount of overflowing volatile components is low and magma fragmentation is not significant, the erupted magma clasts can be very large, often appearing as volcanic bombs. These volcanic bombs are ejected with low energy along the crater at short distances, forming proximal deposits and creating layers of volcanic bomb accumulations.

图8 成都-简阳地区火山碎屑岩典型储集空间 a,b—浆屑内溶蚀孔;c,d—绿泥石晶间孔。

Fig.8 Major pore spaces in the Chengdu-Jianyang volcanics a,b—Intraclastic dissolving pores. c,d—Intercrystalline pores in altered chlorites.