Boron Variation and the Subducted Sediment Component in the Volcanics from the Bifurcated Portion of the Lesser Antilles Island Arc (LAIA)

North of Martinique island the Lesser Antilles volcanic arc bifurcates, creating a double arc. Here volcanic activity has migrated up to 50 km westward with time, resulting in two volcanic lines that are distinct in age. The eastern line, commonly referred to as the old arc, was active from Early Eocene to Mid-Miocene (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al., 1988). The western line, commonly referred to as the recent arc, has been active since the late Pliocene, ~6 Ma ago (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al., 1988). Martinique itself acts as an intersection of the two lines. Volcanic activity on the island has been continuous since the onset of the old arc. This has resulted in the formation of an intermediate arc, defined by a period of volcanic activity from ~ 20– 6 Ma (Westercamp et al., 1989). The present study investigates variation in boron concentration across the two volcanic lines in the northern Lesser Antilles, as well as within Martinique. Boron separation was achieved through a Na2CO3 flux fusion procedure adapted from Ryan and Langmuir (1993). Solutions were then analyzed on an ICP-OES with coupled ESI SC-FAST autosampler. In addition to boron, trace element and major element data were also collected. In total, data on forty-two samples are presented. Fifteen samples are from islands in the old arc. Twenty-one samples are from islands in the recent arc, and six samples from the intermediate arc portion of Martinique. Major observations include: (a) Only subtle differences exist in the trace element, major element, and B content between the old arc and the recent arc; (b) the intermediate arc is chemically distinct from the old and recent arc; (c) B and Ba are decoupled from each other throughout all three building stages of the arc