Source provenance

Hanson, C.R. (1989). The northern suture in the Shigar valley, Baltistan, northern Pakistan. In: Malinconico, L.L. & Lillie, R.J. (eds) Tectonics of the Western Himalayas. Geological Society of America Special Paper 232, 203-215.

Cited by 4 units (4 published) · 8 field-level citations · 3 revision notes.

The Northern Suture (Main Karakoram Thrust) in the Shigar Valley separates Paleozoic shelf-type metasediments of the Asian plate (Daltumbore Formation) from Cretaceous arc metasediments/volcaniclastics of the Ladakh-Kohistan arc (Bauma-Harel Formation, with Cretaceous turritellid gastropods). Metamorphic isograds are cut by the suture (metamorphism predates faulting). Arc intrusion in two phases: pre-tectonic ~100 Ma (tholeiitic) and post-tectonic 40-60 Ma (calc-alkaline). Suture marks closure of a small ocean basin in Late Cretaceous-Early Eocene time.

This page is the reverse of each unit's per-field citations — it shows exactly what this reference supports, making the dataset's “no source, no fact” rule browsable both ways.

Units citing this source

• Mesozoic Bauma Harel Formation Cretaceous–Paleogene
  Fossils
  • Age: Hanson (1989), after Desio (1963): the Bauma-Harel Formation (named from the Bauma-Harel Lungma) is defined as a Cretaceous unit of volcaniclastic metasediments metamorphosed to chlorite-epidote greenschist, interbedded with slate, phyllite, minor carbonate and multicoloured conglomerate, up to ~9 km in outcrop width on the Ladakh-Kohistan arc (south) side of the Northern Suture. Poorly preserved turritellid gastropods (sample PAK/B-85-71, Bauma-Harel Lungma) are tentatively Cretaceous, and it is correlated with the Rakaposhi Volcanics and the Gawuch Formation along the Northern Suture. This arc-cover interpretation qualifies the curated Late-Proterozoic-basement framing (which corresponds to the associated Askore amphibolite/marble basement).
• Paleozoic Daltumbore Formation
  AgeLithologyDepositional environmentType localitySynonymsIntroduced byGeological significance
• Mesozoic Kohistan Batholith Cretaceous-Paleogene
  • Age: Hanson (1989): in the Shigar-valley arc terrane two intrusive phases are exposed — a pre-tectonic, possibly tholeiitic phase about 100 Ma old, and a post-tectonic, calc-alkaline to subalkaline phase 40–60 Ma old — bracketing deformation along the Northern Suture. Madin et al. (1989) group the Mesozoic to middle-Cenozoic mafic metasedimentary and intrusive arc rocks obducted onto the Indian margin along the MMT as the 'Kohistan Sequence'.
• Mesozoic Shigar Group Cretaceous–Paleogene
  • Geological significance: Hanson (1989): the Shigar Valley is crossed by the Northern Suture (Main Karakoram Thrust), a large southwest-verging reverse fault carrying pods of serpentinised ultramafic rock that separates the Paleozoic Asian-plate Daltumbore Formation (northeast) from the Cretaceous Ladakh-Kohistan arc Bauma-Harel Formation (southwest). Metamorphic isograds are cut by the suture, showing regional (high-temperature, low-to-moderate-pressure) metamorphism predated Late Cretaceous–Early Eocene suturing.