ODP Final Technical Report - Ocean Drilling Program - Texas A&M ...

Scientific Resultsglobal environmental changes over the past100 to 120 million years by discovering rapid(decadal) climate change as a global phenomenon,documenting and quantifying climateextremes (including ocean anoxic events)over the last 120 million years, and confirmingdetails of the “hothouse” world 55 millionyears ago when tropical climates prevailed atthe polar regions. ODP scientists proposedthe hypothesis that rapid (decadal) climatechange was initiated by global decompositionof methane hydrates in ocean sediments andconfirmed the timing of the gateway openingbetween Australia and Antarctica, whichwas critical to the establishment of the AntarcticCircumpolar Current that ended the“hothouse” era and began a 40-million-yearcooling of the Earth. ODP scientists establishedthe hypothesis that uplift of the Himalayasenhanced global cooling, determinedthe history of sea level rise and fall over thepast 60 million years, and discovered globalenvironmental impacts caused by the extrusionof large volumes of igneous rocks knownas “large igneous provinces.” Research resultsalso documented extreme drought in CentralEast Africa, thought to have been the impetusfor human migration from Africa 1–2 millionyears ago.Evidence was also found for large amountsof less-heated water percolating through theridge flanks, which has implications for therecycling of ocean water through the crust.Thus, the understanding of the formation ofsubmarine copper and zinc mineral resourceswas revolutionized, leading internationalresource companies to revise their explorationstrategies (annual impact of roughly $500million).We know that Earth was even more thermallyactive during the Cretaceous, when enor-“Scientific ocean drilling has madefundamental contributions to ourunderstanding of the Earth.”mous plumes of mantle rock rose beneaththe lithosphere and triggered the formationof individual volcanoes and volcanic plateausat rates unknown in today’s world. Scientificocean drilling has changed the understandingof the nature and genesis of geologic hazardsby evaluating fluid flow in the accretionaryDuring scientific ocean drilling cruises, evidencewas found for present-day formation ofhuge ore-grade deposits of iron, copper, andzinc precipitated out of hydrothermal fluidsheated to more than 300°C and rising as hotsprings from the center of spreading ridges.33