scholarly journals The Fonualei Rift and Spreading Center: Effects of ultraslow spreading and arc proximity on back-arc crustal accretion

2016 ◽  
Vol 121 (7) ◽  
pp. 4814-4835 ◽  
Author(s):  
Jonathan D. Sleeper ◽  
Fernando Martinez ◽  
Richard Arculus
Keyword(s):  
Spreading Center ◽  
Crustal Accretion ◽  
Back Arc

scholarly journals Geological interpretation of volcanism and segmentation of the Mariana back-arc spreading center between 12.7°N and 18.3°N

2017 ◽  
Vol 18 (6) ◽  
pp. 2240-2274 ◽  
Author(s):  
Melissa O. Anderson ◽  
William W. Chadwick ◽  
Mark D. Hannington ◽  
Susan G. Merle ◽  
Joseph A. Resing ◽  
...  
Keyword(s):  
Spreading Center ◽  
Geological Interpretation ◽  
Back Arc

scholarly journals Origins of chemical diversity of back-arc basin basalts: A segment-scale study of the Eastern Lau Spreading Center

2009 ◽  
Vol 114 (B6) ◽  
Author(s):  
Antoine Bézos ◽  
Stéphane Escrig ◽  
Charles H. Langmuir ◽  
Peter J. Michael ◽  
Paul D. Asimow
Keyword(s):  
Chemical Diversity ◽  
Spreading Center ◽  
Back Arc

Rock and paleomagnetic evidence for the existence and nature of a Cayman Trough spreading center

1978 ◽  
Vol 15 (12) ◽  
pp. 1930-1940 ◽  
Author(s):  
M. J. Clark ◽  
J. M. Hall ◽  
J. W. Peirce
Keyword(s):  
Central Valley ◽  
Spreading Center ◽  
Small Scale ◽  
Low Temperature Oxidation ◽  
Crustal Accretion ◽  
Temperature Oxidation ◽  
Magnetic Parameters ◽  
Mid Atlantic Ridge ◽  
Curie Temperatures

Rock and paleomagnetic measurements have been made on a set of 54 basalts dredged from 17 stations located within the central valley of the Cayman Trough. Seventeen of the samples could be oriented with respect to the in situ vertical by the use of lava cooling ledges and stalactites.Peak remanent intensities in the Cayman Trough are lower than peak Mid-Atlantic Ridge values by a factor of 2 or 3 even after allowance is made for the latitudinal variation in geomagnetic field intensity. This difference is likely to be the result of the combined effects of relatively low saturation magnetization and more advanced low temperature oxidation of titanomagnetite in the Cayman Trough basalts.Five young, reversely magnetized basalts, similar to those found on the Mid-Atlantic Ridge, occur in the Cayman Trough sample set.Plots of the magnetic parameters of the pillow basalts with distance from the axis of the trough show broad highs or lows associated with the axis. Our interpretation is that crustal formation in the central valley has occurred recently, but it has either been rather diffuse or is now much disturbed tectonically on a small scale in comparison with the Mid-Atlantic Ridge. Analysis of the distribution of Curie temperatures suggests that crustal accretion has been slow (0.1–0.4 cm year−1 half-rate) and may have ceased in the area studied at about 0.6 Ma BP.

scholarly journals Crustal accretion at a sedimented spreading center in the Andaman Sea

Geology ◽  
2016 ◽  
Vol 44 (5) ◽  
pp. 351-354 ◽  
Author(s):  
Aurélie Jourdain ◽  
Satish C. Singh ◽  
Javier Escartin ◽  
Yann Klinger ◽  
K.A. Kamesh Raju ◽  
...  
Keyword(s):  
Andaman Sea ◽  
Spreading Center ◽  
Crustal Accretion

scholarly journals Submarine back-arc lava with arc signature: Fonualei Spreading Center, northeast Lau Basin, Tonga

2008 ◽  
Vol 113 (B8) ◽  
Author(s):  
Nicole S. Keller ◽  
Richard J. Arculus ◽  
Jörg Hermann ◽  
Simon Richards
Keyword(s):  
Spreading Center ◽  
Lau Basin ◽  
Back Arc

scholarly journals Crustal structure and evolution of the Niuafo'ou Microplate in the northeastern Lau Basin, Southwestern Pacific

2020 ◽  
Author(s):  
Florian Schmid ◽  
Heidrun Kopp ◽  
Michael Schnabel ◽  
Anke Dannowski ◽  
Ingo Heyde ◽  
...  
Keyword(s):  
Gravity Data ◽  
Seafloor Spreading ◽  
P Wave ◽  
Spreading Center ◽  
Plate Boundaries ◽  
Volcanic Arc ◽  
Lau Basin ◽  
Refraction Seismic ◽  
Wave Tomography ◽  
Back Arc

<p>The northeastern Lau Basin is one of the fastest opening and magmatically most active back-arc regions on Earth. Although the current pattern of plate boundaries and motions in this complex mosaic of microplates is fairly well understood, the structure and evolution of the back-arc crust are not. We present refraction seismic, multichannel seismic and gravity data from a 300 km long east-west oriented transect crossing the Niuafo’ou Microplate (back-arc), the Fonualei Rift and Spreading Centre (FRSC) and the Tofua Volcanic Arc at 17°20’S. Our P wave tomography model shows strong lateral variations in the thickness and velocity-depth distribution of the crust. The thinnest crust is present in the Fonualei Rift and Spreading Center, suggesting active seafloor spreading there. In the much thicker crust of the volcanic arc we identify a region of anomalously low velocities, indicative of partial melts. Surprisingly, the melt reservoir is located at ~17 km distance to the volcanic front, supporting the hypothesis that melts are deviated from the volcanic arc towards the FRSC in sub-crustal domains. We identify two distinct regions in the back-arc crust, representing different opening phases of the northeastern Lau Basin. During initial extension, likely dominated by rifting, crust of generally lower upper-crustal velocities formed. During an advanced opening phase, likely dominated by seafloor spreading, crust of higher upper-crustal velocities formed and is now up to 11 km thick. This thickening is the result of magmatic underplating, which is supported by elevated upper mantle temperatures in this region.</p>

scholarly journals The tectonic and volcanic evolution of the Mangatolu Triple Junction

2020 ◽  
Author(s):  
Rebecca Mensing ◽  
Margaret Stewart ◽  
Mark Hannington ◽  
Alan Baxter ◽  
Dorothee Mertmann
Keyword(s):  
Triple Junction ◽  
Hydrothermal Systems ◽  
Spreading Center ◽  
Valuable Insight ◽  
Triple Junctions ◽  
Lau Basin ◽  
The North ◽  
Spreading Centers ◽  
Spreading Rates ◽  
Back Arc

<p>The Mangatolu Triple Junction (MTJ) is an intraoceanic back-arc spreading center that is host to at least 3 distinct hydrothermal systems. It is located in the NE Lau Basin, which opened due to rollback of the Pacific plate along the Tonga-Kermadec trench. At the MTJ, three spreading centers meet in a ridge-ridge-ridge (RRR)-type triple junction separating the Tonga plate in the east, the Niuafo’ou microplate in the southwest, and an unnamed microplate in the north. The MTJ is directly linked to the formation and evolution of the Northeast Lau microplate mosaic, as plate fragmentation inevitably results in the formation of triple junctions, but it remains unclear whether the spreading centers are the drivers of plate fragmentation or a consequence of stress relocation related to microplate rotation. Detailed investigation of the geology and structural setting of the MTJ therefore provides valuable insight into the development in the northeast Lau Basin. Here we present the first comprehensive 1:200,000 geological map of the MTJ, based on a compilation of marine geophysical data (hydroacoustics, magnetics, and gravity) derived from 7 research cruises that have investigated the region between 2004 and 2018. Analysis of the mapped geological formations at the MTJ shows the importance of relict arc crust originating from the Tofua Arc in the architecture of the triple junction, which includes three stages of back-arc crust development and extensive off-axis volcanism. The spreading centers along each arm of the MTJ exploit pre-existing crustal weaknesses, interpreted to have formed during initial Lau Basin opening. A reconstruction of the basin opening, based on the mapped features and published spreading rates, revealed that initiation of the MTJ commenced approximately 180,000 years ago, consistent with the very recent and ongoing dynamic evolution of the NE Lau Basin and emerging microplate mosaic. Intersecting fabrics indicate sequential evolution of the 3 arms of the triple junction, with extension along the northeast arm dominant in the early history and more recent extension along the southern and western arms. The results of this study contribute to our growing understanding of the tectonic framework of the northeast Lau Basin and the role of triple junctions in microplate formation.</p>

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