Central Mountains Geology of Taiwan

central mountain range

the oldest exposed rocks heavily metamorphosed , found in central mountains. poor quality fossil evidence suggests origin in permian period. form band of rock nan ao in north inland of jinfeng on eastern flank of central mountain range. band 30 km wide in north , narrows south. these earlier rocks heavily metamorphosed. occur basement beneath western part of island. make danana ao group or tananao schist. group consists of kainanagang gneiss, tailuge marble, , changchun schist.

the yuli schist cretaceous in age , consists of black schist , greenschist, glaucophane schist, , spotted slate. easternmost part , extends chian southwards west of chihpen hot springs in belt 150 km long. although dark colour of black schist due carbon, carbon less 2% of content. minerals found quartz, mica, chlorite, albite, sphene, , graphite.

the changchun schist being greenschist found on western side , forms thick beds. found along smaller amounts of chert, , black schist. rock foliated dark green rock containing chlorite, epidote, quartz, calcite, biotite, albite , actinolite. derived mafic volcanic rocks. these rocks can host copper sulfide ores.

siliceous schists coloured grey, metamorphosed sandstone, rich in quartz. quartzite , chert bands can found, , commonly associated black schist.

the chiuchu formation or tailuge marble forms band tailuko in north point between wulu , kuanshan in south. limestone mined in quarries south of suao cement manufacture. although colour shade of grey, there black or white limestone, chopped blocks building purposes. dolomite found along limestone particularly @ chingchangshan, hopingchi, , mukuashan.

the kainangan gneiss or kanagan formation occurs in several elongated bodies. gneiss derived sedimentary rocks contains coarse grained quartz, biotite, , albitic plagioclase. there orthogneiss derived granite. light grey , contains sodic plagioclase, quartz, biotite, , muscovite. within gneiss there pegmatite dikes containing quartz, feldspar , mica.

other igneous rocks found in old metamorphic belt amphibolite , dolerite dikes. serpentinite found 5 km west of fengtien (奉天). contains exploited deposits of nephrite, talc , asbestos. wanjung station (萬榮) close more outcrops of serpentenite. tamayenshan block northwest of juisui (瑞穗) , tsenghuanshan block 10 km west of juisui significant ultramafic outcrops.

green serpentinite near yuli makes quality building stone. band of ultramafic rocks extends 25 km north of litao, taitung (離島).

the area subjected nanao orogeny around 85 ma involved granite intrusion , regional metamorphism. rifting opened south china sea around 40 ma may connected dolerite intrusions. penglai orogeny started 10 ma , continues @ present time.