• How do lithospheric structures vary along continental margins, including old and young 



margins, island arc and trench regions, fast and slow convergence sites, and thiols and 

 thin sedimentary sequences? How are they related to adjacent geologic provinces, 

 onshore basins and tectonics, and offshore basins and trenches? 



• What causes initial rifting? How are conjugate sites on the opposite sides of ocean basins 



related? What are the controlling factors for subsidence rates, sediment accretion rates, 

 thermal histories, and regional basin formation? 



The major elements of this initiative are: 



• Expanded seismic experiments to determine the deep structure in contrasting regions and 



integration of these data with lithologic, acoustic, stratigraphic, structural, and 

 subsidence analyses, and also with heat flow, gravity, and magnetic measurements. 

 Onshore geologic studies of the continental lithosphere should be correlated with offshore 

 drilling by the Ocean Drilling Program. 



• Utilization of state-of-the-art seismic and other geophysical field systems with sufficient 



resources to maintain effective data acquisition and data analysis centers. Attention must 

 be given to maintaining a critical mass of scientists, technicians, and students for these 

 operations. 



• Support for riser drilling on continental margins to determine the age and composition of 



the basement in order to identify seismic reflectors and biostratigraphic data needed for 

 subsidence models and composition and fades of the geologic section. 



Incremental costs will cover modest upgrades of existing academic facilities and support the 

 essential use of these capabilities through the next decade. They also cover coordinated, 

 community-wide use of state-of-the-art industry exploration capabilities. Developmental and 

 operational costs of riser drilling are included under facilities support in the FY 1989-93 

 period. 



Funding Requirements 



A summary budget for Ocean Sciences and component budgets for each Program are provided in 

 the tables of Section IV. 



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