XII Contents
9.3.5 Milankovitch Cycles and Dating ................ 251
9.3.6 A Change in Tune ........................... 253
9.4 The Carbon Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 253
9.4.1 A Major Discovery. . . . . . . . . . . . . . . . . . . . . . . . .. 253
9.4.2 Paleoproductivity ............................ 254
9.4.3 The Long-Range View. . . . . . . . . . . . . . . . . . . . . . .. 257
9.5 Tertiary Oceans: The Cooling Planet. .................. 257
9.5.1 Trends and Events: Oxygen Isotopes ............ 257
9.5.2 The Great Partitioning ........................ 259
9.5.3 The Grand Asymmetries ...................... 260
9.5.4 The Onset of the (Northern) Ice Age ............ 261
9.5.5 The Mid-Miocene Cooling Step ................ 262
9.5.6 The End-of-Eocene Cooling ................... 264
9.6 The Cretaceous!fertiary Boundary .................... 265
9.6.1 The Evidence for Sudden Extinction ............ 265
9.6.2 The Causes of Extinction ..................... 265
9.7 Plate Stratigraphy and CCD Fluctuations ............... 266
9.7.1 Backtracking and CCD Reconstruction .......... 266
9.7.2 Atlantic and Pacific CCD Fluctuations ........... 269
9.7.3 Possible Causes of CCD Fluctuations ........... 270
9.8 Cretaceous Oceans: a Question of Oxygenation. . . . . . . . .. 270
9.8.1 A "Stagnant" Ocean? . . . . . . . . . . . . . . . . . . . . . . .. 270
9.8.2 Modem Analogs ............................ 271
9.8.3 Oxygen in a Warm Ocean. . . . . . . . . . . . . . . . . . . .. 272
9.8.4 Milankovitch in the Cretaceous? ............... 273
9.8.5 "Anoxic Events" and Volcanism ................ 273
10 Resources from the Ocean Floor . . . . . . . . . . . . . . . . . . .. 277
10.1 Types of Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 277
10.2 Petroleum Beneath the Sea Floor . . . . . . . . . . . . . . . . . . . .. 277
10.2.1 Economic Background. . . . . . . . . . . . . . . . . . . . . . .. 277
10.2.2 Origin of Petroleum. . . . . . . . . . . . . . . . . . . . . . . . .. 279
10.2.3 Where Offshore Oil Is Found. . . . . . . . . . . . . . . . .. 280
10.2.4 Present Oil Exploration. . . . . . . . . . . . . . . . . . . . . .. 283
10.3 Raw Materials from Shelves. . . . . . . . . . . . . . . . . . . . . . . .. 285
10.3.1 Phosphorites ................................ 285
10.3.2 Shell Deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 287
10.3.3 Placer Deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 287
10.3.4 Sand and Gravel. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 288
10.4 Heavy Metals on the Deep-Sea Floor. . . . . . . . . . . . . . . . .. 289
10.4.1 Importance of Manganese Deposits. . . . . . . . . . . .. 289
10.4.2 Nature of Manganese Deposits ................. 291
10.4.3 Origin of Manganese Nodules. . . . . . . . . . . . . . . . .. 292
10.4.4 Ores from Spreading Axes . . . . . . . . . . . . . . . . . . .. 294
10.4.5 Red Sea Ore Deposits. . . . . . . . . . . . . . . . . . . . . . .. 297
9.3.5 Milankovitch Cycles and Dating ................ 251
9.3.6 A Change in Tune ........................... 253
9.4 The Carbon Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 253
9.4.1 A Major Discovery. . . . . . . . . . . . . . . . . . . . . . . . .. 253
9.4.2 Paleoproductivity ............................ 254
9.4.3 The Long-Range View. . . . . . . . . . . . . . . . . . . . . . .. 257
9.5 Tertiary Oceans: The Cooling Planet. .................. 257
9.5.1 Trends and Events: Oxygen Isotopes ............ 257
9.5.2 The Great Partitioning ........................ 259
9.5.3 The Grand Asymmetries ...................... 260
9.5.4 The Onset of the (Northern) Ice Age ............ 261
9.5.5 The Mid-Miocene Cooling Step ................ 262
9.5.6 The End-of-Eocene Cooling ................... 264
9.6 The Cretaceous!fertiary Boundary .................... 265
9.6.1 The Evidence for Sudden Extinction ............ 265
9.6.2 The Causes of Extinction ..................... 265
9.7 Plate Stratigraphy and CCD Fluctuations ............... 266
9.7.1 Backtracking and CCD Reconstruction .......... 266
9.7.2 Atlantic and Pacific CCD Fluctuations ........... 269
9.7.3 Possible Causes of CCD Fluctuations ........... 270
9.8 Cretaceous Oceans: a Question of Oxygenation. . . . . . . . .. 270
9.8.1 A "Stagnant" Ocean? . . . . . . . . . . . . . . . . . . . . . . .. 270
9.8.2 Modem Analogs ............................ 271
9.8.3 Oxygen in a Warm Ocean. . . . . . . . . . . . . . . . . . . .. 272
9.8.4 Milankovitch in the Cretaceous? ............... 273
9.8.5 "Anoxic Events" and Volcanism ................ 273
10 Resources from the Ocean Floor . . . . . . . . . . . . . . . . . . .. 277
10.1 Types of Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 277
10.2 Petroleum Beneath the Sea Floor . . . . . . . . . . . . . . . . . . . .. 277
10.2.1 Economic Background. . . . . . . . . . . . . . . . . . . . . . .. 277
10.2.2 Origin of Petroleum. . . . . . . . . . . . . . . . . . . . . . . . .. 279
10.2.3 Where Offshore Oil Is Found. . . . . . . . . . . . . . . . .. 280
10.2.4 Present Oil Exploration. . . . . . . . . . . . . . . . . . . . . .. 283
10.3 Raw Materials from Shelves. . . . . . . . . . . . . . . . . . . . . . . .. 285
10.3.1 Phosphorites ................................ 285
10.3.2 Shell Deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 287
10.3.3 Placer Deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 287
10.3.4 Sand and Gravel. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 288
10.4 Heavy Metals on the Deep-Sea Floor. . . . . . . . . . . . . . . . .. 289
10.4.1 Importance of Manganese Deposits. . . . . . . . . . . .. 289
10.4.2 Nature of Manganese Deposits ................. 291
10.4.3 Origin of Manganese Nodules. . . . . . . . . . . . . . . . .. 292
10.4.4 Ores from Spreading Axes . . . . . . . . . . . . . . . . . . .. 294
10.4.5 Red Sea Ore Deposits. . . . . . . . . . . . . . . . . . . . . . .. 297