Geology Wiki

Mirador Limestone


Porous to massive coralline limestone

Stratigraphic relations

Conformably overlies the Klondyke Formation


Baguio District


Late Miocene


>120 m

Named by

Leith, 1938


Copias Limestone (Encina and Del Rosario, 1978); Labayug Limestone (Francisco, 1974)

Mirador Limestone is a cream-colored, porous, coralline limestone named by Leith (1938) for the outcrop at Mirador Hill in Baguio City. It was presumed by Leith (1938) to be of Plicene age probably because it occupies the hilltops around Baguio City. It has an estimated thickness of over 120 m at MoutnMirador and Dominican Hill (Leith, 1938). This limestone also occupies a ridge to the south of Philex mine and extends up to Ansagan, Tuba, Benguet.

In terms of stratigraphic relations, Mirador Limestone overlies the Klondyke Formation and apparently underlies the Baguio Formation. The conglomerate underlying the limestone along Marcos Highway near the Tuba River Bridge is believed to be part of the Klnodyke Formation, although Maleterre (1989) maintains that it is part of the Zigzag Formation.

Balce (1978) reports a dating of Middle to Late Miocene (Tf2-Tf3) fossils in a limestone sample taken from Marcos Highway, near the junction with Santo Tomas Road. The limestone body here is contiguous with the limestone at Mirador Hill. A limestone sample from the ridge west of Upper Bued Creek was also dated probable Miocene-Pliocene by the Paleontological Section of the Bureau of Mines (file report, 1977). A tentative Late Miocene age is given to the Mirador Limestone on the basis of stratigraphic relations and scanty paleontologic dating.

The Copias Limestone of Encina and Del Rosario (1978) at Barrio Gambang, Atok is probably equivalent to the Mirador Limestone. This massive, cream to pink limestone body is 150 m thick and reported to be confined within the pyroclastic beds of Klondyke Formation, about 200 m above its base. The limestone, containing Middle Miocene to Late Miocene foraminifera, was reported by Paleontological Section of the Bureau of Mines and Geosciences (file report, 1977) as probably reworked.

The Mirador Limestone is also probably correlative to the Labayug Limestone (Francisco, 1974 cited in Lorentz, 1984) whose type locality is at the Northern Cement quarry in Barrio Labayug, Sison, Pangasinan. The nature of the contact with the underlying Klondyke formation is not clear, since it is hidden, while its contact with the overlying Amlang Formation at Sapid Creek is gradational. It has a thickness of 290 m at the type locality but thins out towards the north. It is dated Late Miocene.