The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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AAPG Bulletin; Year: 2025; Issue: April DOI: 10.1306/03182524012
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Figure 4. Photomicrographs of well A thin sections. (A) Quartz vein (QV) filled by chalcedony rims (CR) and megaquartz (MQ) in the center cutting a shrubstone host rock. Note irregular walls and the association with rounded clasts of host rock (HRC). Open porosity is secondary and associated with quartz cement and solid bitumen (SB). Younger QVs crosscut the older structures. Plane-parallel transmitted light. (B) Shrubstone with QV filled by CR, MQ, and HRC. Cross-polarized transmitted light. (C) Vuggy fracture filled with MQ and SB. Note irregular walls and truncated growth lines on shrubs, evidence of dissolution of fracture walls. Host-rock relicts (HRR) are seen in the form of small circular inclusions and often follow the fracture wall. Plane-parallel transmitted light. (D) Backscattered electron microscopy/energy-dispersive spectroscopy image of banded CR with a calcitic host rock clast (HRC) and banding around smaller inclusions. (E) Small displacement fault with cataclastic texture (Caf) is crosscut by a vein filled by CR and MQ. Plane-parallel transmitted light. (F) A QV crosscutting a shrubstone host rock. The vein crosscuts an older cavity filled with a dolomitized micritic infill (DMI). Primary porosity (PP) is preserved between shrubs and secondary porosity by shrub dissolution (DS) is common. The detail shows dolomite (Dol) and quartz (Qtz) filling the fracture. Plane-parallel transmitted light.
Figure 4. Photomicrographs of well A thin sections. (A) Quartz vein (QV) filled by chalcedony rims (CR) and megaquartz (MQ) in the center cutting a shrubstone host rock. Note irregular walls and the association with rounded clasts of host rock (HRC). Open porosity is secondary and associated with quartz cement and solid bitumen (SB). Younger QVs crosscut the older structures. Plane-parallel transmitted light. (B) Shrubstone with QV filled by CR, MQ, and HRC. Cross-polarized transmitted light. (C) Vuggy fracture filled with MQ and SB. Note irregular walls and truncated growth lines on shrubs, evidence of dissolution of fracture walls. Host-rock relicts (HRR) are seen in the form of small circular inclusions and often follow the fracture wall. Plane-parallel transmitted light. (D) Backscattered electron microscopy/energy-dispersive spectroscopy image of banded CR with a calcitic host rock clast (HRC) and banding around smaller inclusions. (E) Small displacement fault with cataclastic texture (Caf) is crosscut by a vein filled by CR and MQ. Plane-parallel transmitted light. (F) A QV crosscutting a shrubstone host rock. The vein crosscuts an older cavity filled with a dolomitized micritic infill (DMI). Primary porosity (PP) is preserved between shrubs and secondary porosity by shrub dissolution (DS) is common. The detail shows dolomite (Dol) and quartz (Qtz) filling the fracture. Plane-parallel transmitted light.