Early Dinantian evaporites of the Easton-1 well, Solway Basin, onshore, Cumbria, England
Early Dinantian evaporites of the Easton-1 well, Solway Basin, onshore, Cumbria, England
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英国坎布里亚陆上索尔韦盆地 Easton-1 井的早期迪南特蒸发岩
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发表时间：
1997
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通讯作者：
J. Ward
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作者：
J. Ward
摘要 1990 年，在坎布里亚陆上 Solway 盆地的 Easton-1 井中发现了早期 Viséan 富含硬石膏的碳酸盐碎屑岩层序，垂直厚度为 3784 英尺（无基底）。该层系在地层上位于下边界群，在露头处仅发现了蒸发岩的痕迹。建议将该序列命名为“下边界群伊斯顿硬石膏相”，缩写为“EA Beds”。 EA 床分为三个单元。顶部的 1 号单元厚约 400 英尺，包含两层混合岩性中向上增厚的硬石膏层。 2 号单元厚约 2100 英尺，由九个石灰岩、页岩和砂岩循环层序组成，并夹有许多硬石膏夹层。几个序列的总体相似性表明相似的起源。 2 号单元序列分为三个兆周期，两个约 750 英尺厚，一个约 590 英尺厚。沉积被解释为是在干旱或部分干旱的气候条件下发生的，在一个浅且快速但均匀沉降的盆地内，海平面的上升和下降受冰川升降控制。许多 2 号单元的硬石膏层被解释为水下成因。 3 号单元厚约 1500 英尺，显示出复杂的循环模式，在米兰科维奇 10 万年和 40 万年的周期内，在轨道诱导控制下，沉积显然直接响应太阳照射。地震解释表明，EA层的区域范围大于1000平方公里。
Abstract An early Viséan, anhydrite-rich, carbonate-clastic succession, of vertical thickness 3784 feet (no base) was found in 1990 at the Easton-1 well in the Solway Basin, onshore Cumbria. The succession is stratigraphically located in the Lower Border Group where only traces of evaporites had been found at outcrop. It is proposed to name the succession the ‘Easton Anhydrite Facies of the Lower Border Group’, abbreviated to ‘EA Beds’. The EA Beds are divided into three units. Unit 1 at the top, about 400 feet thick, contains two sequences of upwardly thickening anhydrite beds within mixed lithologies. Unit 2, about 2100 feet thick, consists of nine cyclic sequences of limestones, shales and sandstones with numerous interbeds of anhydrite. Overall similarity of several of the sequences suggests similar origins. Unit 2 sequences are grouped into three megacycles, two of approximately 750 feet and one 590 feet thick. Deposition is interpreted to have taken place in arid or partly arid climatic conditions, within a shallow and rapidly, but uniformly subsiding basin with glacio-eustatically controlled rise and fall of sea level. Many of the Unit 2 anhydrite beds are interpreted to be of subaqueous origin. Unit 3, about 1500 feet thick, displays complex patterns of cyclicity with sedimentation apparently responding directly to solar insolation under orbitally induced control within Milankovitch periodicities of 100 000 and 400 000 years. Seismic interpretation indicates that the regional extent of the EA Beds is greater than 1000 km2.