Shallow water chemosynthetic assemblages occur in response to glacio-eustasy

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Followings are our main results of the study.1. Cores recovered normal to bedding plane and yielding fossil cold seep assemblage indicate that seep was periodically activated in response with glacio-eustacy reconstructed on oxygen isotope fluctuations of foraminifers.2. Authigenic carbonates of ancient seep sites are well preserved a substratum-normal profile of interstitial geochemical characteristics. We can designate ancient sulfate-methane interface(SMI)horizons in the cores based on carbon isotope ratios where archaeon biomarkers are greatly concentrated.3. We discover slump structures in some strata, about 500m in paleodepth, in association with allochthonous cold seep bivalves. These occurrences evidently suggest drastic decomposition events of methane hydrates.4. We discover a modem and a thousand years ago cold seep bivalve communities in the shelf environments shallower than 200m in depth. These are the shallowest cold seep bivalve communities so far as we know.5. We first discover cold seep fossil assemblages from Neogene of Philippines. The Philippine assemblages show greatly wide range of mode of occurrences.