Leg 183 Synthesis: Kerguelen Plateau–Broken Ridge—A Large Igneous Province

Abstract

The Kerguelen Plateau and Broken Ridge form a large igneous province (LIP) in the southern Indian Ocean. The main objectives of Ocean Drilling Program Leg 183 were to understand the origin and evolution of this LIP and the impact of its formation on the environment. Igneous basement (33 to 233 m of penetration) has been recovered from 11 drill sites on the LIP, and 7 are Leg 183 sites. Studies of the basement and sediment cores lead to the following conclusions. Although an important caveat is that we have access only to uppermost basement of a thick (~20 km) igneous crust, these results are inconsistent with massive volcanism associated with a single plume head and continental breakup. 2. The uppermost igneous basement is dominantly tholeiitic basalt. Based on the physical characteristics of the lava flows, which indicate subaerial eruption, and the occurrence of overlying terrestrially derived sediments containing wood fragments, fern remains, and terrestrial palynoflora, much of the LIP was above sea level when magmatic output was high. 3. The geochemical characteristics of basalt forming the LIP are unlike mid-ocean-ridge basalt (MORB). There are, however,

Formation and evolution of Shatsky Rise oceanic plateau: Insights from IODP Expedition 324 and recent geophysical cruises

“…Instead, the evidence says that Shatsky Rise reached sea level, but not much higher. Thus, Shatsky Rise is between OJP and Kerguelen Plateau, with the former formed well below sea level (Michael, 1999; and the latter erupted subaerially (Coffin, 1992;Frey et al, 2003). In addition, seismic refraction data from Tamu Massif display a curious negative correlation between seismic velocity and crustal thickness, not the positive correlation expected from a hotter thermal anomaly (Korenaga and Sager, 2012).…”

“…This fits Shatsky Rise between Kerguelen and Ontong Java plateaus in its emplacement depth. The former was largely emplaced subaerially (Coffin, 1992;Frey et al, 2003) whereas the latter was mostly emplaced >1 km below sea level (Michael, 1999;Roberge et al, 2005). That Shatsky Rise was never highly emergent implies that its evolution was different than Iceland, a ridgecentered hotspot and possible mantle plume, which has an elevation of ~ 2 km (Ito et al, 2003).…”

The Mozambique Ridge: a document of massive multistage magmatism

“…Proportions stated in the uppermost part of the graph yield ratios of total crustal volume to areal extent of each LIP. (Agulhas Plateau: Parsiegla et al 2008;Columbia River CFB: Hooper 1988;Baksi 1989;Coffin & Eldholm 1994;Kerguelen Plateau: Coffin & Eldholm 1994;Frey et al 2003;Manihiki Plateau: Coffin & Eldholm 1994;Inoue et al 2008).…”

Origin and evolution of the sub-Antarctic islands: the foundation

“…-n1e island to be devoid of evidence of glaciation signs of elevation during its 8c Kent 1989 'Ule northward movement of India also coincided with the initiation of a Large Igneous Province (LIP) which led to the formation of the Kerguelen Plateau (Duncan 2002, Frey et al 2003, Quilty 2006. Because of its size, and as a high proportion of the Kerguelen Plateau lies below sea level, it is not well sampled except on the few islands and through deep sea drilling.…”

“…Francis & Coffin 1992. It may also have been a major source of carbon dioxide (Frey et al 2003) with Greenhouse effects (Hansen et al 2007). It is also likely that a thinned fragment of continental crust remains under Elan Bank, west of the main body of Kerguelen Plateau, and evidence of a continental component elsewhere on the plateau was encountered during drilling by ODP Leg ]83 in 1999 (Ingle et al 2002).…”