Extensive rock deposits at the base of the Emeishan large igneous province in China ? previously interpreted as sediments shed from a rapidly uplifting dome ? formed as a result of interaction between lava and sea water, suggests a paper online this week in Nature Geoscience. These findings challenge a major assumption of models that implicate a mantle plume in triggering the Emeishan flood basalt eruptions ~260 million years ago.
Ingrid Ukstins Peate and Scott Bryan conducted detailed geological fieldwork and documented the physical characteristics of rocks at the base of the Emeishan province. They found that the earliest eruptions occurred at or near sea level. They found no evidence of extensive doming and uplift of the land surface prior to the eruptions ? a hallmark of plume models.
The team concludes that the Emeishan province did not undergo plume-induced uplift before the onset of volcanism.