Open AccessGeological interpretation of volcanism and segmentation of the M ariana back‐arc spreading center between 12.7° N and 18.3° N
Author(s) -
Anderson Melissa O.,
Chadwick William W.,
Hannington Mark D.,
Merle Susan G.,
Resing Joseph A.,
Baker Edward T.,
Butterfield David A.,
Walker Sharon L.,
Augustin Nico
Publication year - 2017
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2017gc006813
Subject(s) - geology , magmatism , tectonics , back arc basin , volcano , volcanism , magma , rift , arc (geometry) , ridge , seismology , paleontology , subduction , geometry , mathematics
The relationships between tectonic processes, magmatism, and hydrothermal venting along ∼600 km of the slow‐spreading Mariana back‐arc between 12.7°N and 18.3°N reveal a number of similarities and differences compared to slow‐spreading mid‐ocean ridges. Analysis of the volcanic geomorphology and structure highlights the complexity of the back‐arc spreading center. Here, ridge segmentation is controlled by large‐scale basement structures that appear to predate back‐arc rifting. These structures also control the orientation of the chains of cross‐arc volcanoes that characterize this region. Segment‐scale faulting is oriented perpendicular to the spreading direction, allowing precise spreading directions to be determined. Four morphologically distinct segment types are identified: dominantly magmatic segments (Type I); magmatic segments currently undergoing tectonic extension (Type II); dominantly tectonic segments (Type III); and tectonic segments currently undergoing magmatic extension (Type IV). Variations in axial morphology (including eruption styles, neovolcanic eruption volumes, and faulting) reflect magma supply, which is locally enhanced by cross‐arc volcanism associated with N‐S compression along the 16.5°N and 17.0°N segments. In contrast, cross‐arc seismicity is associated with N‐S extension and increased faulting along the 14.5°N segment, with structures that are interpreted to be oceanic core complexes—the first with high‐resolution bathymetry described in an active back‐arc basin. Hydrothermal venting associated with recent magmatism has been discovered along all segment types.