Baltoro Granite
Early Miocene (~21 Ma; U–Pb zircon emplacement 21.0 ± 0.5 Ma)
Neogene in the time scale →Cited in 9 sources Last reviewed Aug 2, 2026
- Rank
- Not recorded
- Status
- Published
- Age
- Cenozoic · Neogene · Early MioceneEarly Miocene (~21 Ma; U–Pb zircon emplacement 21.0 ± 0.5 Ma)
- Named by
- Not recorded
- Type locality
- Baltoro Glacier, Karakoram35.7500°N, 76.3000°E
- Thickness
- Plutonic body (10+ km)
- Lithology
- Biotite granite, muscovite granite, leucogranite
- Synonyms
- Not recorded
A Miocene collision-related granite and leucogranite batholith beneath the Baltoro Glacier and K2 region, formed by melting of thickened crust long after the India-Asia collision.
Major batholith underlying Baltoro Glacier and K2 region. Collision-related leucogranite recording peak metamorphism and melting.
Fossils
Not recorded
Contacts
Band colour = period; texture = dominant rock type. Lines between bands mark the contact type; dotted = no contact recorded in the sources (not a claim of conformity). True scale makes height ∝ recorded thickness; hatched = thickness not recorded. Ages approximate, for ordering.
This unit (highlighted) within its province column; faded ends continue above and below. Line style marks the contact type.
Distribution & setting
- Basin
- Not recorded
- Region
- Not recorded
- Depositional environment
- Not recorded
- Coordinates
- 35.7500°N, 76.3000°E
See it in the field
Geoheritage site where this unit is exposed at outcrop.
Correlation
Not recorded. Compare this unit against other basins on the correlation panel →
Economic significance
Not recorded
Remarks
A large post-collisional crustal-melt batholith of the south-central Karakoram underlying the Baltoro Glacier and K2-Trango region. Emplaced in the early Miocene (U-Pb zircon ~21 Ma), with crustal-melt biotite-muscovite-garnet leucogranites yielding U-Pb ages of roughly 21-13 Ma; records crustal melting some ~30 Myr after the India-Asia collision.
Research notes (6)
Field-by-field findings drawn from the cited literature. Every statement is traced to a registered source — follow a citation for the full reference.
Age & correlation (5)
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Kazmi & Jan (1997): the Baltoro Granite is a post-collisional Miocene pluton of the Karakoram (Axial) Batholith — U-Pb zircon 21 ± 0.5 Ma (Urdukas; Parrish & Tirrul 1989), stretching ~100 × 10–20 km through the central Karakoram — of massive co-magmatic monzogranite to leucogranite (with orbicular biotite granite on the Trongo Towers and leucogranite dykes), interpreted as lower-crustal melts with a mantle input; drove contact metamorphism (M3) at 25–21 Ma. Corroborates the curated Miocene (25–12 Ma) age.
Kazmi, A.H. & Jan, M.Q. (1997)
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Searle et al. (1989): the Baltoro Plutonic Unit (BPU) — biotite monzogranite to two-mica ± garnet leucogranite and pegmatite-aplite of mildly peraluminous affinity — is the youngest magmatic phase of the composite Karakoram batholith, with a U-Pb crystallisation age of 21 ± 0.5 Ma and K-Ar mica cooling ages of 11.7–5.25 Ma. It is a postcollisional crustal melt derived from deep crustal levels (petrogenesis distinct from the High Himalayan leucogranites), emplaced after the India–Eurasia collision along the southern Karakoram.
Searle, M.P., Rex, A.J., Tirrul, R., Rex, D.C., Barnicoat, A. & Windley, B.F. (1989)
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Corroborated by Searle (2011) and Rex et al. (1988): the Baltoro Granite is the Miocene axial post-collisional leucogranite of the Karakoram batholith, emplaced during crustal thickening after the India-Asia collision. Consistent with the recorded Miocene (25-12 Ma) age.
Searle, M.P. (2011)
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Tightened from "Miocene (25-12 Ma)" to an Early Miocene emplacement of 21.0 ± 0.5 Ma from U–Pb zircon dating (Parrish & Tirrul 1989), a late- to post-tectonic phase of the Karakoram batholith; monazite ages 17–19 Ma record slow post-emplacement cooling, and Precambrian zircon inheritance indicates a crustal-melt source.
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U-Pb dating shows the Baltoro granite batholith was assembled over c. 26.4-13 Ma as a suite of biotite-muscovite-garnet leucogranites (Trango Towers, Cathedral, K2-Gasherbrum), a long-lived Miocene crustal-melt event (Searle et al. 2010).
Searle, M.P., Parrish, R.R., Thow, A.V., Noble, S.R., Phillips, R.J. & Waters, D.J. (2010)
Geological significance (1)
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Searle et al. (1989): thermal effects of BPU emplacement define the M3 metamorphism of the central Karakoram (andalusite-cordierite at Mitre Peak indicating ≤3.75 kbar / ~12.5 km depth; sillimanite-grade melt pods at Paiyu), overprinting the regional syntectonic Barrovian M2 (kyanite-garnet, ~550 °C / 5.5 kbar). Older subduction-related phases of the batholith include the Jurassic Hushe complex and the Cretaceous (82–75 Ma) Muztagh Tower metagranitoids; the M2-cutting Mango Gusar two-mica granite is 37.0 ± 0.8 Ma.
Searle, M.P., Rex, A.J., Tirrul, R., Rex, D.C., Barnicoat, A. & Windley, B.F. (1989)
Sources (9)
- Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
- OpenStreetMap contributors and GEOnet Names Server (public geographic gazetteers), used to geolocate named GSP type localities to approximate decimal coordinates.
- Parrish, R.R. & Tirrul, R. (1989). U-Pb age of the Baltoro granite, northwest Himalaya, and implications for monazite U-Pb systematics. Geology, 17(12), 1076-1079.
- Searle, M.P., Parrish, R.R., Thow, A.V., Noble, S.R., Phillips, R.J. & Waters, D.J. (2010). Anatomy, age and evolution of a collisional mountain belt: the Baltoro granite batholith and Karakoram Metamorphic Complex, Pakistani Karakoram. Journal of the Geological Society, 167(1), 183-202.
- Kazmi, A.H. & Jan, M.Q. (1997). Geology and Tectonics of Pakistan. Graphic Publishers, Karachi.
- Kazmi, A.H. & Abbasi, I.A. (2008). Stratigraphy and Historical Geology of Pakistan. Department & National Centre of Excellence in Geology, University of Peshawar, Peshawar. 524 pp. ISBN 978-969-9119.
- Searle, M.P., Rex, A.J., Tirrul, R., Rex, D.C., Barnicoat, A. & Windley, B.F. (1989). Metamorphic, magmatic, and tectonic evolution of the central Karakoram in the Biafo-Baltoro-Hushe regions of northern Pakistan. In: Malinconico, L.L. & Lillie, R.J. (eds) Tectonics of the Western Himalayas. Geological Society of America Special Paper 232, 47-73.
- Rex, A.J., Searle, M.P., Tirrul, R., Crawford, M.B., Prior, D.J., Rex, D.C. & Barnicoat, A. (1988). The geochemical and tectonic evolution of the central Karakoram, North Pakistan. Philosophical Transactions of the Royal Society of London A, 326, 229-255.
- Searle, M.P. (2011). Geological evolution of the Karakoram Ranges. Italian Journal of Geosciences, 130(2), 147-159.
Reviewer confidence: medium
Every fact on this page is source-cited. This entry is part of the peer-archived Pakistan Stratigraphy Dataset (doi.org/10.5281/zenodo.21363991, CC‑BY‑4.0).
Lexicon status: Appears in a single-author Geological Survey of Pakistan memoir (Malkani & Mahmood 2017), not cross-confirmed against the Shah lexicon. The Stratigraphic Committee of Pakistan is largely inactive, so documented provenance — not formal ratification — is the available signal.
Cite this unit
Qudsi, L. (2026). Baltoro Granite. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991
@misc{stratigraphypk_baltorogranite,
author = {Qudsi, Lareb},
title = {{Baltoro Granite} --- Pakistan Stratigraphy Dataset},
year = {2026},
publisher = {Zenodo},
doi = {10.5281/zenodo.21363991},
url = {https://doi.org/10.5281/zenodo.21363991}
} Archived dataset: doi.org/10.5281/zenodo.21363991 (CC‑BY‑4.0) · Direct link to this entry: https://stratigraphy.pk/formation/baltoro-granite (accessed October 29, 2026).
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