What does this research mean for the field?

Authigenic quartz in the Dongying Sag continental shales consists of three genetic types that evolve through three depth-dependent diagenetic stages, significantly influencing reservoir porosity, connectivity, and brittleness. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To identify the origins, silica sources, and diagenetic evolutionary stages of authigenic quartz in continental lacustrine shales.

September 14, 2026Geological Journal

Characteristics and Genetic Types of Authigenic Quartz in Paleogene ES 3 and ES 4 Shales, Dongying Sag

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To identify the origins, silica sources, and diagenetic evolutionary stages of authigenic quartz in continental lacustrine shales.
Examined Paleogene ES3 and ES4 lacustrine shale samples from the Dongying Sag across burial depths ranging from 3300 to 4600 m.
Analyzed quartz morphology, elemental distribution, and mineral assemblages using petrographic thin sections, field-emission scanning electron microscopy with energy-dispersive spectroscopy (FE-SEM-EDS), and X-ray diffraction (XRD).
Identified three primary quartz genetic types: terrigenous detrital quartz, mineral-transformation-derived silica spherules and microcrystalline quartz, and biogenic microcrystalline quartz laminae.
Established a three-stage vertical diagenetic sequence with depth: initial silica spherule precipitation, coexisting spherules and microcrystalline quartz, and stable microcrystalline quartz growth.
Determined that organic-matter-driven smectite-to-illite transformation and feldspar dissolution supply silica for mineral transformation, while biogenic silica forms permeable microcrystalline laminae that enhance pore preservation, brittleness, and fracability.

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Implication

Mineralogical analysis reveals authigenic quartz origins and diagenetic stages in Paleogene lacustrine shales, indicating key controls on reservoir quality and fracability.

Cite This Study

Zheng et al. (2026) studied this question.

synapsesocial.com/papers/6aa7b40e0926e14a848b384a https://doi.org/10.1002/gj.70479

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Implication

Mineralogical analysis reveals authigenic quartz origins and diagenetic stages in Paleogene lacustrine shales, indicating key controls on reservoir quality and fracability.

Characteristics and Genetic Types of Authigenic Quartz in Paleogene ES 3 and ES 4 Shales, Dongying Sag

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Discussion

Implication

Cite This Study

Characteristics and Genetic Types of Authigenic Quartz in Paleogene ES 3 and ES 4 Shales, Dongying Sag

Key Points

Discussion

Implication

Cite This Study

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