Hotspot volcanism along a leaky fracture zone contributes the formation of the 85?E Ridge at 11?N latitude, Bay of Bengal

作者：Shang, Luning^*; Hu, Gang^*; Pan, Jun; Clift, Peter D.; Li, Hailong; Zhang, Yong; Yang, Chuansheng; Wu, Hao; Ran, Weimin

来源：Tectonophysics, 2022, 837: 229453.

DOI：10.1016/j.tecto.2022.229453

• 85? E Ridge
• Leaky fracture zone
• Hotspot volcanism
• Crustal structure
• Seismic reflection

The 85??E Ridge is a prominent linear structure in the northeastern Indian Ocean. Its nature and origin are still controversial due to the coverage of thick Bengal Fan sediments. Here we present a newly collected 400-km-long 2-D seismic reflection profile which crosses the 85??E Ridge near 11??N and shows the basement morphology and internal structures of the ridge. The ridge has a thickened crust characterized by two basement highs rising up to -2???3 km above the surrounding oceanic crust and a Moho depression with amplitude of -3???4 km. Typical volcanic structures formed by hotspot volcanism are identified in the ridge. Deep-rooted faults played important roles in the formation of the 85??E Ridge. They acted as the preferred conduit for the upwelling of hotspot melts, but their syn- and post-volcanic reactivations induced the collapse of volcanic sequences and the relative uplift of the East Ridge. These observations support that the 85??E Ridge near 11??N having formed by hotspot magmatism drained along a leaky fracture zone. Combined with previous results, a new single-hotspot formation model of the 85??E Ridge is proposed, in which the entire 85??E Ridge was formed by a weak and pulsating mantle plume acting on the northward drifting Indian Plate. Its along-strike variations in location, morphology, and structure in different segments are interpreted to reflect different elastic strength of the oceanic lithosphere and the existence of a pre-existing fracture zone which laterally redistributed the shallow melts.

• 单位
  桂林理工大学