Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas
Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas
复制标题
DOI：
10.1306/11020606059
复制
发表时间：
2007-04-01
期刊：
影响因子：
3.5
通讯作者：
Ruppel, Stephen C.
中科院分区：
文献类型：
--
作者：
Loucks, Robert G.;Ruppel, Stephen C.
沃斯堡盆地的密西西比系巴内特组是一个典型的页岩气系统，其中岩石是源、储集层和封盖层。巴内特地层沉积在一个深水前陆盆地，与开放的海洋循环不良。在盆地的大部分历史中，底部沃茨是富氧的，保存了有机质，因此形成了丰富的烃源岩，沿着有丰富的草莓状黄铁矿。巴内特层段包括多种相，但以细粒（粘土至粉砂级）颗粒为主。根据矿物学、组构、生物群和结构，可识别出三种一般岩相：（1）层状硅质泥岩;（2）层状泥质石灰泥岩（泥灰岩）;（3）骨架状泥质石灰砂岩。每个相都含有丰富的黄铁矿和磷酸盐（磷灰石），这在硬地中特别常见。早期成岩作用的产物碳酸盐结核也很常见。整个巴内特生物群由半远洋泥柱、稀释浊积岩和泥石流从陆架或上部含氧斜坡搬运到盆地的碎屑组成。生物沉积物也来源于较浅，更好的含氧水柱。据估计，巴内特沉积发生在2500万年前。时期，尽管亚岩相发生变化，但沉积风格在整个时期内保持显着相似。
The Mississippian Barnett Formation of the Fort Worth Basin is a classic shale-gas system in which the rock is the source, reservoir, and seal. Barnett strata were deposited in a deeper water foreland basin that had poor circulation with the open ocean. For most of the basin's history, bottom waters were euxinic, preserving organic matter and, thus, creating a rich source rock, along with abundant framboidal pyrite. The Barnett interval comprises a variety of facies but is dominated by fine-grained (clay- to silt-size) particles. Three general lithofacies are recognized on the basis of mineralogy, fabric, biota, and texture: (1) laminated siliceous mudstone; (2) laminated argillaceous lime mudstone (marl); and (3) skeletal, argillaceous lime packstone. Each facies contains abundant pyrite and phosphate (apatite), which are especially common at hardgrounds. Carbonate concretions, a product of early diagenesis, are also common. The entire Barnett biota is composed of debris transported to the basin from the shelf or upper oxygenated slope by hemipelagic mud plumes, dilute turbidites, and debris flows. Biogenic sediment was also sourced from the shallower, better oxygenated water column. Barnett deposition is estimated to have occurred over a 25-m.y. period, and despite the variations in sublithofacies, sedimentation style remained remarkably similar throughout this span of time.