Possible Perturbations to Hotspot Traces and Implications for the Origin and Structure of the Line Islands.

摘要

Perturbations to hotspot signals recorded on the surface of the earth will produce hotspot traces with characteristics more complex than those of simple time-progressive volcanic chains. Some of these perturbations are a consequence of normal plate tectonics, some are observed interactions of hotspot magmatism with lithospheric structure and processes, and others are hypothetical. The Line Islands volcanic chain has a complex structure and some characteristics that cannot be reconciled with those expected of a simple time-progressive hotspot trace. Two models for the development of the Line Islands are presented. Model 1 assumes that the Line Islands were formed between 130 and 67 Ma, and model 2 assumes an age span of 90 to about 15 Ma and incorporates the Tuamotu Islands as an extension of the Line Islands. In model 1 most of the complex structure and subsidence of the chain can be explained in terms of perturbations to the hotspot signal. Model 2 gives a good geometric fit to the volcanic chain but fails to explain the anomalous subsidence of the Line Islands.