Vertical tectonics in northern Escanaba Trough as recorded by thick late Quaternary turbidites

Escanaba Trough, the southernmost segment of the Gorda Ridge, is filled by as much as 500 m of late Quaternary turbidite and hemipelagic sediment. Gor ing at Deep Sea Drilling Project Site 35 and Ocean Drilling Program (ODP) S ites 1037 and 1038 together with 4.5-MIz deep-tow and 3.5-kHz surface-ship seismic reflection profiles enable a distinct pattern of reflections to be mapped throughout Escanaba Trough in the upper part of this sediment fill. The uppermost 80 m of turbidite sediment, which includes at least 11 turbid ity current events, were deposited in <7 kyr. Nine of these turbidites are found throughout Escanaba Trough at water depths >3200 m. The turbidity cur rents were trapped upon entering Escanaba Trough, resulting in all of the s ediment in suspension in the flows being deposited. The thickness of the tu rbidite layers reflects both the flow thickness and the vertical grain conc entration within the flow that deposited the layer. Variations in the turbi dite thickness with respect to water depth can be used to estimate the degr ee of relative vertical movement within the floor of Escanaba Trough. In th e area of hydrothermal activity near ODP Site 1038, uplift of as much as 14 0 m has occurred over the past 8 kyr.