2.3. Characteristics of geological terrains in the Sinwulu and Luye
catchments
The Pilushan Formation lies at the west side of the Sinwulu and
Luye catchments. The major lithologies in the formation are slate,
phyllite, metamorphic mudstone and sandstone. Lenticular volcanic
rocks are often found in the formations, an important indication of the
Eocene formations of the Central Range. Limestones and marls also
can be found in the formations.
The Tananao Complex underwent several periods of metamorphosis,
and the grade of metamorphosis increases toward the east
(Fig. 1A). The rocks in the Tananao Complex – schist, marble,
amphibolite and granitic gneiss – constitute the oldest crystalline
basement of Taiwan. The initial rocks of the Black Schist are
carbonaceous shale, siltstone and sandstone. The foliation structures
are well developed in the Black Schists. The Mixed Schist outcrops
in the downstream areas of the Sinwulu and Luye catchments.
The major lithologies in the Mixed Schists are silica schist, green
schist and black schist. The outcrop area of the marble in the Sinwulu