SEDIMENTATION IN THE DEEP SEA 



By Hans Petiersson 



Oceanografisca Institutet 

 Goteborg 4, Sweden 



A new era in submarine geology was opened through the develop- 

 ment of the new technique first used from the Swedish Deep-Sea Expe- 

 dition with the "Albatross" in 1947-48. Cores of unprecedented length 

 approaching 20 metres were raised from great depths by means of the 

 Nullenberg piston-core sampler. The thickness of the sediment layers 

 in the open oceans was for the first time measured by means of Wei- 

 bull's seismic reflexion method. The water-layers immediately above 

 the deep-sea bottom were sampled by F. Koczy and their content of 

 suspended particles studied by Jerlov, whereas detailed achogiams of the 

 bottom configuration down to depths of about 7000 metres were re- 

 gistered by a new kind of echograph, revealing the microstructure of 

 the ocean floor. Finally, the first values were obtained of the geothermal 

 gradient in the deep-sea deposits by means of a geothermometer plunged 

 into the bottom to a depth of over 10 metres. My short summary to be 

 given here of the new aspects obtained through this and through fol- 

 lowing expeditions (Danish, British and American) will be limited to 

 sedimentation in the deep sea, as revealed mainly through the study 

 of the long "Albatross" cores, especially through work by Gustaf Ar- 

 rhenius, geologist to our expedition, for a number of E. Pacific cores. 



The 200 and odd "Albatross" cores were taken along a course of 

 over 40,000 nautical miles in all three oceans. Mainly for technical 

 reasons, the course was laid near the Equator. Our studies have prin- 

 cipally been directed towards stratification, rate of sedimentation, total 

 thickness, radioactivity and, to a certain extent also, diagenetic akera- 

 tions, sources and transportation. 



Our long cores revealed that stratification of the sediments, earlier 

 considered as rather exceptional, is on the contrary very common, es- 

 pecially near the equator, where the equatorial current system gives 

 rise to zones of divergence with upwelling deep water, rich in nutrient 

 salts and consequently also in plankton-vegetation and -population. 

 Highly spectacular cases of abrupt changes in the composition of the 

 sediment, especially transitions from Red Clay to Calcareous Ooze and 

 vice versa, were often found. From his study of the S. Pacific cores 

 Arrhenius has been able to draw conclusions regarding the paleocli- 



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