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At the Miocene/Pliocene, approximately 5.33 million years ago, the Strait of Gibraltar opened and has remained open since. There are now 8 miles (13 kilometers) of ocean between Europe and Africa at the strait's narrowest point.3.161 Can you imagine what it must have been like when the Atlantic Ocean first broke through the straits, and water poured into this giant version of California's Death Valley? The amount of water needed to fill up this basin had a major impact on sea level worldwide, and provides another source of eustatic sea level changes, besides the stacking of ocean water at the poles during ice ages. These changes, unlike the minor impact of hurricanes like Katrina and Rita, create a major change in the geologic record. Certainly related to why the Miocene/Pliocene geologic boundary has been identified and correlated worldwide. It is interesting that today, because evaporation is more rapid than river and rain replenishment in the Mediterranean Sea, the flow of water through the Straits of Gibraltar is almost continuously from west to east into the basin. Figure 52 shows the location of the Straits of Gibraltar relative to the extent of the Mediterranean Sea, and also highlights the relative location of the Dead Sea, the Zagros Fold Belt, and a study I was involved in offshore Mozambique in 1991. This process of isolation and evaporation of large bodies of water, creation of salt layers, and covering of those salt layers with sands and shales has been repeated in various places and at various times over the history of the Earth. Scientists are now coming to know these specifics much better than has ever been know before by mankind.
More detailed examples of sedimentation processes helps to tie together this story about salt domes. South of the Mediterranean Sea, on the east coast of Africa, is an area where we studied these depositional processes in detail. Dr. V. Kolla, a world class seismic stratigrapher from India had a set of data from offshore Mozambique, which he had permission to publish. Dr. Brad Macurda and I had done several papers on the stratigraphy of the deep water Porcupine Sea Bright, offshore southwest Ireland, and discussions led to us working with Dr. Kolla on the offshore Mozambique data. This was one of the most interesting geological studies I have been involved in. We presented the results at at the 1991 Annual Convention of the American Association of Petroleum Geologists,3.162 and at a Society of Exploration Geophysicists Research Workshop3.163 in 1991. The examples below are from slides and posters prepared for these presentations.
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paradoxes