The paper presents comprehensive mineralogical and geochemical characteristics of Dominican amber-bearing sediments from Siete Cañadas, Hato Mayor Province of the Eastern Mining District (EMD) in the Cordillera Oriental. The characteristics of rocks collected from the borehole in Siete Cañadas area (EMD) were compared with petrography of coaly shales from La Cumbre in the Northern Mining District (NMD). The mineralogy of the rocks was determined using transmitted and reflected light microscopy, scanning electron microscopy, Powder X-ray diffraction and Fourier Transform Raman Spectroscopy. Biomarker analyses by the gas chromatography–mass spectrometry were used to trace the genetic source and transformation stage of organic matter hosted in the core sediments. In this study, the characteristics of rocks from La Cumbre were supplemented with the petrographic data from our studies reported earlier. Based on the findings, it has been concluded that the basins in the investigated parts of the EMD and NMD regions were likely characterized by different, isolated palaeosettings. Transformation and maturation of terrigenous material were affected by locally occurring physicochemical conditions. In both amber deposits, the sedimentation of clastic and organic material proceeded in the presence of marine conditions. In case of the La Cumbre deposit (NMD area), the sedimentation underwent probably in the conditions of the lagoon environment, a shallow maritime lake or periodically flooded plain that facilitated organic matter decomposition and carbonation from meta-lignite to sub-bituminous coal (random reflectance of coal—R_r^o = 0.39%). In the Siete Cañadas (EMD region), the sedimentation took place in a shallow saltwater basin, where terrigenous material was likely mixed with material found in situ (fauna fossils, carbonate-group minerals) to form the mudstones enriched in bituminous substance of low maturity. The organic matter found in the rocks from both deposits is of mixed terrestrial/marine origin and was deposited in the presence of low oxygen concentration and reducing and/or dysoxic conditions.

本文介绍了东科迪勒拉东部矿区 (EMD) 哈托市长省 Siete Cañadas 的多米尼加琥珀沉积物的综合矿物学和地球化学特征。将从 Siete Cañadas 地区 (EMD) 钻孔中采集的岩石特征与北部矿区 (NMD) 的 La Cumbre 煤质页岩的岩石学特征进行比较。使用透射和反射光显微镜、扫描电子显微镜、粉末 X 射线衍射和傅里叶变换拉曼光谱测定岩石的矿物学。气相色谱-质谱联用生物标志物分析用于追踪岩心沉积物中有机质的遗传来源和转化阶段。在这项研究中，La Cumbre 岩石的特征补充了我们之前报告的研究中的岩相学数据。根据这些发现，得出的结论是，EMD 和 NMD 地区调查部分的盆地可能具有不同的、孤立的古环境。陆源物质的转化和成熟受到当地发生的物理化学条件的影响。在这两个琥珀矿床中，碎屑和有机物质的沉积都是在海洋条件下进行的。在 La Cumbre 矿床（NMD 地区）的情况下，沉积可能是在泻湖环境、浅海湖或周期性洪水平原的条件下进行的，这些条件促进了有机质分解和从变质褐煤到次烟煤的碳化（随机煤的反射率——R_r ^o  = 0.39%）。在 Siete Cañadas（EMD 地区），沉积发生在浅咸水盆地，在那里陆源物质可能与原位物质（动物群化石、碳酸盐矿物）混合形成富含低成熟度沥青物质的泥岩. 在这两个沉积物的岩石中发现的有机物是陆/海混合来源，并且是在低氧浓度和还原和/或缺氧条件下沉积的。