CORRELATION OF DOLOMITE OCCURRENCE WITH SEDIMENTATION RATE CHANGE
会议名称：《理论与应用地球物理研讨会》
会议日期：2002年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
关 键 词：seismic resolution modeling synthetic seismogram thin-bed dolomite formation sedimentation rate age model
摘 要：正 During the expedition on board the R/V JOIDES Resolution, Ocean Drilling Program （ODP） Leg 186, it is discovered that there exists several thin layers of dolomitic rocks imbedded in otherwise uniform diatomaceous silty sediments and claystone. The thickness of the dolomite layers ranges from 0.5 m to 2 m as estimated from the in-situ log data. In this paper we demonstrate that these thin dolomite layers can have profound influence to alter seismic appearance, even on conventional low-frequency seismic data. Using advanced amplitude-preserving high resolution enhancement techniques, a high-resolution dolomite imaging profile is obtained crossing one of the drill site. We provide the first geophysical evidence of large-scale dolomite occurrence in the dynamic forearc basin developed in the deep-sea terrace on the landside of the Japan *** occurrence of thin dolomitic layers embedded in diatomaceous sediments is on the basin scale rather than an isolated phenomenon. The genesis of dolomite in the natural environment has been one of the outstanding problems in geology over the last two centuries. However, we find that these thin dolomite layers mostly occur at depths where abrupt sedimentation rate change occurs. Two dolomite layers also coincide with the Miocene/Pliocene and Pliocene/Pleistocene age boundaries. It seems to suggest that the correlation between the dolomite layer occurrence and abrupt sedimentation rate change be intrinsically related to and a signature of dramatic changes in depositional environments. Considering the fact that the sedimentation rate at the ODP Leg 186 sites may be as fast as 250 m/m.y., high-resolution seismic stratigraphic model could help obtain a regional biostratigraphic or age model. The methodology can well be applied to other similar environments.