Silurian and Devonian marine shales and limestones of the Barrandian Basin host abundant black solid, non-fluorescing bitumens that fill tectonic fractures and veins, and occlude fossil moulds and diagenetic concretions. Solid bitumen, interpreted as thermally degraded petroleum, entered the rocks during several successive episodes of fracture-bound petroleum migration that occurred during deeper burial of the strata. Regional distribution of bitumen reflectance values that range between ∼0.9–2.3% R, correlate with variations of its FT-IR and Raman spectroscopic characteristics and aromatic hydrocarbon composition, and collectively evidence the maturity trend increasing across the basin from the southwest to the northeast. The reflectance of chitinozoans and graptolites (∼0.8–1.9% R) in the country rocks and homogenization temperatures of hydrocarbon fluid inclusions document palaeotemperatures ranging between ∼90–150 °C, characteristic of the oil window zone grading into the gas/condensate zone. Although in a basin-wide perspective the averaged values of solid bitumen and zooclast optical reflectance converge and indicate the same northeastern-increasing regional diagenetic trend, solid bitumen reflectance values vary considerably at individual localities and even within some bitumen samples. The wide scatter of optical reflectance values and the heterogeneity of optical properties, which were attributed to the presence of multiple source rocks in the basin, the variable lithology of bitumen host rocks, or other variables, hamper the use of solid bitumen as a simple alternative to zooclast/vitrinite reflectance palaeothermometers in a given basin. On the other hand, the highly anisotropic domain and the mesophase “coking” textures of the solid bitumen that were recognized in the NE part of the basin provide unique evidence on an anomalous, hitherto unrecognized, geologically short-lasting thermal event that affected the Palaeozoic rocks. A line of indirect evidence suggests that the coking of the bitumen was caused by a cryptic intrusion, possibly a concealed branch of the Central Bohemian Pluton, which intruded into the strata during the Variscan orogeny. More rarely occurring semi-solid, vividly yellow fluorescing waxy bitumen, that postdates solid bitumen in some fractures and voids, does not reveal a regional thermal maturation trend. It precipitated from relict waxy oils that migrated through the strata during a post-Neogene uplift of the Barrandian region.

中文翻译：

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固体沥青作为石油运移、热成熟度和接触变质作用的指标：捷克共和国巴兰德盆地（志留纪 - 泥盆纪）的案例研究

巴兰迪亚盆地的志留纪和泥盆纪海相页岩和石灰岩含有丰富的黑色固体、无荧光沥青，它们填充构造裂缝和矿脉，并封闭化石模具和成岩结核。固体沥青被解释为热降解石油，在地层更深埋藏过程中发生的几次连续的断裂束缚石油运移过程中进入岩石。沥青反射率值的区域分布范围在~0.9-2.3% R 之间，与其 FT-IR 和拉曼光谱特征以及芳烃组成的变化相关，并共同证明了整个盆地从西南到东北成熟度增加的趋势。围岩中几丁虫和笔石（~0.8-1.9% R）的反射率和烃类流体包裹体的均一温度记录了古温度范围在~90-150°C之间，这是石油窗口区分级到天然气/凝析油区的特征。尽管从全盆地的角度来看，固体沥青和动物碎屑光学反射率的平均值收敛并表明相同的东北部增加的区域成岩趋势，但固体沥青反射率值在各个地点甚至在某些沥青样品内差异很大。由于盆地中存在多种烃源岩、沥青母岩的岩性变化或其他变量，光学反射率值的广泛分散和光学特性的异质性阻碍了使用固体沥青作为简单的替代品给定盆地中的动物碎屑/镜质体反射古温度计。另一方面，在盆地东北部发现的固体沥青的高度各向异性区域和中间相“焦化”结构，为影响古生代的异常的、迄今为止未被认识的、地质上持续时间较短的热事件提供了独特的证据。岩石。一系列间接证据表明，沥青的焦化是由神秘的侵入物引起的，可能是波西米亚中部岩体的一个隐蔽分支，在瓦里斯坎造山运动期间侵入地层。更罕见的半固态、鲜艳的黄色荧光蜡状沥青，在一些裂缝和空隙中晚于固态沥青，没有揭示区域热成熟趋势。它是在巴兰第地区后新近纪隆起期间通过地层迁移的残余蜡质油中沉淀出来的。