The opening of the Central Atlantic Ocean was accompanied by ascending plume zones that generated large igneous provinces (LIPs), such as the Central Atlantic Magmatic Province (CAMP), with voluminous lava flows and outpourings. One of the best records of the CAMP in the West Gondwana is the Jurassic volcanic-sedimentary succession exposed in the western Parnaíba Basin, northern Brazil. Diagenetic and hydrothermal processes are discussed, focusing on the lava-sediment interaction. The siliciclastic sediments called “intertrap deposits” record a wet desert system characterized by fluvial-aeolian and shallow lake deposits engulfed by lavas of the CAMP at approximately 200–202 Ma. The facies and petrographic studies, based on a drill core and outcrops, led to the interpretation of the palaeoenvironmental and diagenetic evolution of the intertrap deposits. The intertrap deposits are sandwiched by basalts and may be organized in seven sedimentary facies, grouped into two facies associations: 1) ephemeral braided river deposits (FA1), which consist of medium- to coarse-grained pebbly sandstone with poorly sorted angular to sub-rounded grains (basaltic fragments and quartz) and low-angle cross-bedding, even-parallel stratification, and trough cross-stratification, and 2) pond/shallow lake deposits (FA2) composed of tabular beds of sandstone/siltstone rhythmite and laminated mudstone. The main architectural elements of intertrap deposits are 1) channels on volcanic substrate, 2) sand sheets deposited over pre-existent lava topography, 3) tabular beds with laminated rhythmites, and 4) sand-filled fissures/fractures and clastic dykes. The intensification of magmatic processes due to the disruption of Pangaea promoted the formation of extensive volcanic plains, whereas wet desert settings were developed during the quiescent intervals between lava flow episodes. Fluvial channels with subaqueous dunes and sand sheets were incised into the basaltic substrate. The abandoned fluvial plains were affected by flash floods that promoted mechanical infiltration of clays, forming coatings over grains. The heat flow and hydrothermal activity of volcanic rocks increased the devitrification of glassy clasts, releasing silica and precipitating low-temperature authigenic mineral assemblages. The most common pore-filling process was the massive precipitation of early diagenetic-hydrothermal minerals, including smectite, chalcedony, poikilotopic zeolite, megaquartz, and haematite, which partially obliterated the primary porosity and permeability. These exceptional conditions of cementation triggered by basalt eruptions precluded the modification of a primary framework by late stages (post-Jurassic) burial diagenesis. The intertrap sandstones represent the last lava-sediment interaction related to the CAMP recorded in West Gondwana.

中大西洋的开放伴随着上升的羽状带，这些羽状带产生了大型的火成岩省（LIP），例如中大西洋岩浆省（CAMP），熔岩流和倾泻量很大。西贡多瓦纳CAMP的最好记录之一是在巴西北部的帕纳伊巴盆地西部暴露的侏罗纪火山-沉积沉积演替。讨论了成岩作用和热液作用过程，重点是熔岩-沉积物相互作用。称为“夹层沉积物”的硅质碎屑沉积物记录了一个湿沙漠系统，其特征是在约200-202 Ma的时间里，河床和浅湖沉积物被CAMP的熔岩吞没。基于钻芯和露头的岩相和岩石学研究，导致对圈套间沉积物的古环境和成岩演化的解释。圈套间的沉积物被玄武岩夹在中间，可以分为七个沉积相，分为两个相：1）短辫状河床沉积物（FA1），由中度至粗粒度的卵石状砂岩组成，角向至亚分度的分类较差。圆形颗粒（玄武岩碎屑和石英）和低角度交叉分层，均匀平行分层和低谷交叉分层，以及2）由砂岩/粉砂岩脉动和叠层泥岩的板状床组成的池塘/浅湖沉积物（FA2） 。圈套间沉积物的主要结构元素是：1）火山基底上的河道； 2）沉积在既有熔岩地形上的砂岩片； 3）带有层状节律的板状床；4）充满沙子的裂缝/裂缝和碎屑堤。由于Pangea的破坏而引起的岩浆作用的加剧促进了广阔的火山平原的形成，而在熔岩流发作之间的静止间隔期间形成了湿润的沙漠环境。将具有水下沙丘和沙床的河道切入玄武质基底。废弃的河床平原受到山洪泛滥的影响，山洪泛滥促进了粘土的机械渗透，从而在谷物上形成了涂层。火山岩的热流和热液活动增加了玻璃质碎屑的失透作用，释放出二氧化硅并沉淀出低温自生矿物组合。最常见的孔隙填充过程是早期成岩热液矿物的大量沉淀，包括蒙脱石，玉髓，iki石沸石，兆晶石和赤铁矿，部分消除了主要的孔隙度和渗透率。这些由玄武岩喷发引发的胶结作用的特殊条件排除了后期（侏罗纪后）埋藏成岩作用对主要框架的改造。圈套砂岩代表了西贡多瓦纳记录的与CAMP有关的最后熔岩-沉积作用。