台灣西南部化石珊瑚礁的發育和衰退過程及其古海洋環境的研究

We surveyed the fossil reefs in southwestern
Taiwan to study the formation and transition
of coral reefs in turbid environment. Six
types of cold-seep carbonates can be
distinguished based on the results of field
surveys and drilling-core analyses. They are
column-like, mound-like or biohermal,
plume-like, mushroom-like, lamellar
structures, as well as pebbles, cobbles &
boulders. These types of carbonates share the
following characteristics: (1) all developed in
low energy environment; (2) a harder
structure indicating a more complete
diagenesis; (3) sedimentation occurred
simultaneously with diagenesis; (4)
containing few fossils, mainly L. goliath; (5)
developed near faults, clinal or anticlinal
axes; (6) absence of large scale disturbances
in nearby areas; (7) neighboring areas still
rich in natural gas recently. In addition, the
results of X-ray analyses showed that the
major composition of these cold-seep
carbonates are dolomite, dolomite (ferroan),
ankerite, kutnahorite, and crystals although
few samples contained calcite and aragonite.
The results indicated that there were
widespread cold-seeps before the
development of coral reefs in southwestern
Taiwan and the cold-seep carbonates
provided the hardground for the formation of
coral reefs during the shallowing of structural
highs on the foreland basin.