Question: Adriana Ocampo has led six research expeditions to study what geological formation that is more than 180 km in diameter and 20 km in depth

<P0-S0>  Its center is located near the town of Chicxulub, after which the crater is named. <P0-S1>  It was formed by a large asteroid or comet about 10 to 15 kilometres (6 to 9 miles) in diameter, the Chicxulub impactor, striking the Earth. <P0-S2> The Chicxulub crater ( ; ] ) is an impact crater buried underneath the Yucatán Peninsula in Mexico. <P0-S3>  The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (K–Pg boundary), slightly less than 66 million years ago, and a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth suddenly became extinct, including all non-avian dinosaurs. <P0-S4>  The crater is more than 180 km in diameter and 20 km in depth, well into the continental crust of the region of about 10–30 km depth. <P0-S5>  It makes the feature the third of the largest confirmed impact structures on Earth. <SEP> <P1-S0> The East Warburton Basin in South Australia is the site of a large impact crater of the Carboniferous period (around 360-300 million years ago). <P1-S1>  The subterranean structure lies buried at a depth of ~4 km, and measures a minimum of 200 km in diameter. <P1-S2>  For comparison, Chicxulub crater is about 180 km in diameter. <SEP> <P2-S0> Wong How Man (born 1949) is an explorer and photojournalist from Hong Kong, and founder and president of the China Exploration & Research Society (CERS), a preeminent nonprofit organization specializing in exploration, research, conservation and education in remote China. <P2-S1>  Between 1974, when he began exploring China as a journalist, and 1986, when he founded CERS, Wong led six major expeditions for the "National Geographic" magazine. <P2-S2>  His writing for the "National Geographic" was nominated for the Overseas Press Club Award of America. <P2-S3>  In his 1985 "National Geographic" expedition, Wong led a team that found a new source of the Yangtze River that is internationally recognized as the true geographic source of the river. <P2-S4>  During this expedition he came across the hanging coffins, Wong developped a long life obsession with this peculiar coffins. <P2-S5>  Wong documented this expedition in his 1989 book, "Exploring the Yangtze: China's Longest River". <P2-S6>  Twenty years later, Wong led a team to discover a new source, four miles west of the source that he had previously discovered. <P2-S7>  Subsequently, Wong led CERS expeditions that pinpointed the source of the Mekong in 2007 and discovered a new source for the Yellow River in 2008. <P2-S8>  In 2011, he and his team defined the source of the Salween River. <SEP> <P3-S0> Adriana Ocampo is a Colombian planetary geologist and the Science Program Manager at NASA Headquarters. <P3-S1>  Her research contributed to the understanding of the Chicxulub impact crater. <P3-S2>  Ocampo and her colleagues also discovered the Aorounga Crater Chain in Chad in 1996. <P3-S3>  She has led six research expeditions to the Chicxulub impact site.