THE RELATIONSHIP BETWEEN AUTHIGENIC CARBONATE AND GAS HYDRATES IN MAKRAN ACCRETIONARY WEDGE: ON THE BASIS OF M74/3 CRUISE REPORT OF " R/V METEOR" IN 2007

In order to reveal the relationship between authigenic carbonate and gas hydrate in the Makran accretionary wedge, we hereby summarized all the data from the M74/3 cruise of "R/V Meteor" in 2007. The data shows that authigenic carbonate rock has no strict corresponding relationship with gas hydrate. In the sea area where methane flux was very high (such as the No. 5 plume site where water is 2 900 m deep, plume 1 800 m high, with gas hydrates of tubular structure), authigenic carbonate usually does not occur on the seabed or shallow sediments where gas hydrate usually exists. However, in the sea area where methane flux is high (such as, at the No. 2 plume site where water is 1 100 m deep, plume 170 m high, with gas hydrates of vesicular structure), and if there is a small amount of authigenic carbonate on the seabed or in the shallow sediments, then hydrate usually occurs; if there is great amount of authigenetic carbonate on seabed or in shallow sediments, then there is usually no hydrate occurred. Based on the current data, it is uncertain whether there is hydrate in deep sediments. In the sea area where methane flux is very low (such as at MUC-4site, there are no plumes), sediments show clear lamination, there is neither authigenic carbonate nor hydrate.