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doi:10.2204/iodp.proc.324.205.2014

Introduction

Shatsky Rise was cored during Integrated Ocean Drilling Program Expedition 324 because it is a unique oceanic plateau formed mainly during the Late Jurassic and Early Cretaceous at a rapidly spreading triple junction, with characteristics that could be attributed to either a plume or plate model of formation (Sager, 2005). Shatsky Rise is also a gigantic volcanic construct whose formation style is poorly understood. The goal of Expedition 324 was to core the igneous rock of Shatsky Rise and the sediment above to examine the age, physical volcanology, geochemistry, and tectonic evolution of the rise as well as the sedimentation history (Sager et al., 2010, 2011).

Thermal and alternating field (AF) demagnetizations were carried out by the shipboard paleomagnetists on discrete samples in order to give an estimate of the inclination of the recorded geomagnetic field. These shipboard results were reported in the Expedition Reports (see the “Expedition 324 summary” chapter [Expedition 324 Scientists, 2010]. In order to carry out more detailed paleomagnetic studies, more samples were collected as minicores for thermal and AF demagnetizations to be carried out in several laboratories on shore. Whenever possible, four or five samples were cut for each flow unit. To better understand the magnetic mineralogy of the sampled flows, I collected a slice of sample from the bottom of each minicore from Sites U1346, U1347, and U1350 for hysteresis measurements. Some results were presented in Carvallo and Camps (2013), but that study focused on a few lava flows that were selected for paleointensity study (Carvallo et al., 2013). Hysteresis measurements were subsequently made on the larger suite of samples and are presented here.