Source provenance

Maldonado, F., Khan, S.H. & Mengal, J.M. (1994). Preliminary Geologic Map of Parts of Loralai, Sibi, Quetta, and Khuzdar Divisions, Balochistan Province, West-Central Pakistan. U.S. Geological Survey Open-File Report 94-689, 20 p., 1 sheet.

Cited by 15 units (15 published) · 18 field-level citations · 14 revision notes.

Full-text (user-supplied). USGS-GSP cooperative geologic map (Balochistan Coal-Basin Synthesis Study) with detailed lithology, thickness (with localities), contacts and ages for Sibi-Urak trough, Khojak flysch, Sulaiman-Kirthar shelf, Muslim Bagh Ophiolite and Bagh Complex units. Primary source. Records the Fatmi et al. (1986) renaming of the Parh Group to the Mona Jhal Group, the Alozai Group elevation of the Loralai and Spingwar formations (Fatmi, in press), the Bibai Formation (Kazmi 1979), and Muslim Bagh Ophiolite K-Ar ages of 82-67 Ma.

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Units citing this source

• Mesozoic Alozai Group Jurassic
  LithologyIntroduced byMember unitsAgeEpoch
• Mesozoic Bibai Formation Cretaceous
  AgeLithologyThicknessThickness (m)Type localityIntroduced byDepositional environmentGeological significanceDescription
• Cenozoic Bostan Formation Quaternary
  • Lithology: Corroborated by USGS OFR 94-689: Pleistocene lacustrine clay (gypsiferous), conglomerate and salt-and-pepper sandstone; unconformable on older strata; ~750 m thick in the Pishin Basin (Cheema et al. 1977).
• Cenozoic Chamalang (=Ghazij) Group Paleogene
  • Lithology: Equated with the lower Eocene Ghazij Formation of USGS OFR 94-689 (divided into upper/middle/lower zones around the flanks of the Sibi-Urak trough); the upper zone is reddish-weathering claystone with minor conglomeratic sandstone and local bog iron, ~215 m thick in the Mach area.
• Mesozoic Chiltan Limestone Jurassic
  • Type locality: Corroborated by USGS OFR 94-689: the Middle Jurassic Chiltan Limestone is mapped in the Chiltan Range southwest of Quetta and southeast of Kach and Gogai.
• Quaternary Dada Formation Quaternary
  ThicknessThickness (m)
  • Thickness: Gap-fill (thickness field was empty). USGS OFR 94-689 (Maldonado et al. 1994) reports the Dada Conglomerate as about 1,000 m thick in the Urak area of the Sibi-Urak trough (after Hunting Survey Corporation 1961). Confidence medium: the USGS Dada Conglomerate is the Sibi-Urak-trough correlative and the measurement is locality-specific.
• Cenozoic Gaj Formation Neogene
  • Lithology: Corroborated by USGS OFR 94-689: greenish-gray, variegated, gypsiferous shale with subordinate calcareous ferruginous crossbedded sandstone and argillaceous fossiliferous limestone (Miocene? to Oligocene?).
• Cenozoic Kirthar Formation Paleogene
  • Lithology: Corroborated by USGS OFR 94-689: the middle-and-lower Eocene Kirthar Formation is light-gray to pale-brown, thick-bedded to massive, highly fossiliferous limestone interbedded with marl and shale (~50% marl/shale) of the marine-shelf sequence.
• Mesozoic Loralai Formation Jurassic
  • Synonyms: USGS OFR 94-689 records that the Loralai Formation, formerly a member of the Shirinab Formation (Williams 1959; Fatmi 1977), was elevated to formational status as the upper formation of the Alozai Group (Loralai over Spingwar) by Fatmi (in press).
• Mesozoic Mona Jhal Group Cretaceous
  • Synonyms: USGS OFR 94-689 records that the Parh Group of Hunting Survey Corporation (1961) was renamed and redefined by Fatmi et al. (1986) as the Mona Jhal Group, comprising in descending order the Mughal Kot Formation, Parh Limestone, Goru Formation and Sembar Formation, and locally including the Bibai Formation below the Mughal Kot Formation in the eastern part of the map area.
  • Name: Renamed from 'Parh Group' to Mona Jhal Group: Fatmi et al. (1990) — confirmed by USGS OFR 94-689 — superseded the Hunting (1961) 'Parh group' with the Mona Jhal Group (Sembar, Goru, Parh and Mughal Kot formations). The Parh Limestone is retained as a constituent formation.
• Mesozoic Muslim Bagh Ophiolite Cretaceous
  Depositional environment
  • Age: USGS OFR 94-689 gives the Muslim Bagh Ophiolite Complex a Late Cretaceous age based on K-Ar ages of 82-67 Ma (Sawada et al. 1992); emplacement onto the continental margin of the Indo-Pakistan block is now placed in the Late Cretaceous to early Paleocene (Kojima et al. 1994), revising the earlier middle Paleocene-early Eocene emplacement estimate (Allemann 1979; Otsuki et al. 1989). The complex hosts chromite, magnesite and magnetite deposits.
• Quaternary Sakhi Sarwar Group Quaternary
  • Member units: Corroborated by USGS OFR 94-689: the group's molasse — the Dada Conglomerate (Pleistocene; ~1000 m in the Urak area, HSC 1961) and the Bostan Formation (= Boston) — is mapped in the Sibi-Urak trough, resting with angular unconformity on older strata. Lifts this record off the single (Malkani 2017) baseline.
• Mesozoic Sembar Formation Cretaceous
  • Thickness: USGS OFR 94-689 (after Fatmi 1977) gives the Sembar Formation a type-section thickness of ~135 m in the Marri-Bugti area (~30 km east of the map area), thinning near Quetta and Ziarat; the black silty shale is glauconitic and pyritic with phosphatic nodules in the basal part and commonly bears belemnites.
• Mesozoic Shirinab Formation Triassic-Jurassic
  Depositional environment
  • Depositional environment: Gap-fill (environment field was empty). USGS OFR 94-689 describes the Shirinab Formation as thin- to medium-bedded limestone (fine to coarse grained, shelly, oolitic, pisolitic, pelitic) interbedded with calcareous fissile shale, >1,500 m thick in the Quetta Valley (Khan et al. 1986) — a shallow-marine shelf-carbonate succession.
• Mesozoic Spingwar Formation Triassic
  • Synonyms: USGS OFR 94-689 records that the Spingwar Formation, originally named by Williams (1959) and designated the lower member of the Shirinab Formation by Fatmi (1977), is now the lower formation of the Alozai Group (Fatmi, in press); it is locally intruded by diabase sills, with an exposed thickness of ~1,300-2,000 m (Hunting Survey Corporation 1961).