18. PARAMETERS CONTROLLING ACOUSTIC （18岁。）.pdfVIP

Winterer, E.L., Sager, W.W., Firth, J.V., and Sinton, J.M. (Eds.), 1995 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 143 18. PARAMETER S CONTROLLING ACOUSTIC PROPERTIE S OF CARBONATE AND VOLCANICLASTIC SEDIMENT S AT SITE S 866 AND 869 1 2 3 Jeroen A.M. Kenter and Michael Ivanov ABSTRACT Comparison of the acoustic and index properties with the petrographic character of 125 brine-saturated carbonate and volcaniclastic rocks from Sites 866 and 869 indicates that porosity is the dominant parameter influencing P- and S-wave velocity and acoustic impedance. Porosity in the mid-Cretaceous platform carbonates (Site 866) is controlled by diagenetic alteration, rather than primary depositional texture. Replacement and cementation by dolomite yields the highest acoustic velocities. Similarly, porosity in the volcaniclastics (Site 869) is controlled by diagenetic alteration of components and partial replacement and cementing by zeolite. The density-velocity relationship of the carbonates shows excellent correlation with Gardners curve for limestone. The general Gardners curve, however, underestimates the velocities of the volcaniclastics. Laboratory porosity-velocity trends of the carbonates are consistently 5% to 20% higher than those predic