ABSTRACT
Drilling core shows that this Indonesian reef rock resembles mostly fragments of the sizes between rubbles and debris, suggesting its neritic brooding environment, short deposit history, rudimental stage of development when the major mineral contents of aragonite and high-magnesia calcite have not yet changed, and therefore weak diagenesis. The rock even takes the form of loose gravel structure, with extremely weak mass strength (Zeng et al. 1997). X-ray diffraction of the reef rock shows that the content CaCO3 takes ups high percentage of its ingredient, up to even 99%, mainly carbonate particles deposit from biological skeletal debris. Visual observation of the drilling core shows that the rock is gray-white in color, loose in inter-granular connection, while still retaining the original biological skeleton with porous and karst texture Figure 1a. So the density of the rock is smaller than other ordinary limestone, being between 1.33∼2.56 g/cm3. Observed the rock flakes under polarizing microscope, fossil detritus can
1 INTRODUCTION
Coral reef, deposit with rich calcium and insoluble carbonate material, is a type of calcareous rock developed mainly in tropical ocean environment under the biological (reef, seaweed, shellfish and other ocean species) formation and geological formation. It is widely distributed in the tropical waters between 30° south latitude and 30° north latitude.
