Dhruma or Darma (Arabic: ضرما) is a small town located 73.4 kilometres (45.6 mi) by road northwest of Riyadh, Saudi Arabia. [1] It is the center of the small Dhurma Governorate of Riyadh Province, and had a population of 10,267 people according to the 2004 census.

The Dhruma Formation in Saudi Arabia is divided into three formal members (Lower, Middle, and Upper) and seven discrete informal units (units D1–D7; Vaslet et al. 1983, 1985a, b; Manivit et al. 1985a, b). The formation is assigned an Early Bajocian to middle Callovian age based on ammonite and calcareous nanofossils.

The Dhruma Formation was studied at its type locality (Khashm adh Dhibi) in well-exposed sections that serve as examples of the complete Middle Jurassic stratigraphy at its maximum thickness on the Arabian Plate (Powers et al. 1966). The …

2017年5月28日 · The Dhruma Formation shows a substantial and regular thickening to the northwest. Together with the underlying Mafraq Formation and the lower part of the Tuwaiq Mountain Formation, the Dhruma Formation belongs to Biozone F45 (Pfenderina salernitana and Pfenderina trochoidea) after an unpublished scheme from Sikkema .

2014年4月1日 · Organic geochemical (Rock Eval, TOC) and organic petrographic analyses of the sample have confirmed the occurrence of low maturity coal in the Dhruma Formation in the Az Zilfi area, which has potential for surface coal mining as well as for microbial gas generation.

2019年1月1日 · The objective of this study is to document the sedimentology and dynamic stratigraphy of the Dhruma siliciclastic in northern central Arabia, modifying the existing Middle Jurassic paleogeographic map in Saudi Arabia and providing a correlation with the Dhruma reservoir-equivalent outcrops in southern central Arabia.

The age of the Dhruma<br>Formation is based primarily on ammonites and nautiloids but supplemented by micropalaeontological<br>and palynological evidence. Carbon and oxygen isotope determinations complement the<br>biostratigraphic evidence.

1997年10月1日 · Hughes Clark (1988) describes the Dhruma in Oman (714 ft) as a complete cycle of sedimentation. The lower and middle limestone are mud-supported while the upper part is dominantly grain-supported. The Dhruma in Oman is Middle to Late Jurassic based on microfossils and subsurface correlations with Saudi Arabia . The Upper Mafraq, described ...

2024年2月16日 · Carbonate outcrops of the Jurassic Middle Dhruma Formation (D5 and D6 units), located southwest of Riyadh, Saudi Arabia, were investigated to characterize controls on potential reservoir quality.

The Dhruma lies unconformably on the Early Jurassic (Middle to Late Toarcian) Marrat Formation and is unconformably overlain by the Middle Jurassic (Middle to Late Callovian) Tuwaiq Formation. An allostratigraphic, sequence-based reinterpretation of the originally defined Dhruma now assigns the Atash and Hisyan Members, previously of the ...