The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center
Abstract At the Galapagos triple junction in the equatorial Pacific Ocean, the Cocos‐Nazca spreading center does not meet the East Pacific Rise (EPR) but, instead, rifts into 0.4 Myr‐old lithosphere on the EPR flank. Westward propagation of Cocos‐Nazca spreading forms the V‐shaped Galapagos gore. Si...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2020-06-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2020GC008957 |
| _version_ | 1797638073060687872 |
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| author | Deborah K. Smith Hans Schouten Ross Parnell‐Turner Emily M. Klein Johnson Cann Charles Dunham Gabriella Alodia Iker Blasco Benjamin Wernette Dominik Zawadzki Elvira Latypova Sara Afshar Scott Curry |
| author_facet | Deborah K. Smith Hans Schouten Ross Parnell‐Turner Emily M. Klein Johnson Cann Charles Dunham Gabriella Alodia Iker Blasco Benjamin Wernette Dominik Zawadzki Elvira Latypova Sara Afshar Scott Curry |
| author_sort | Deborah K. Smith |
| collection | DOAJ |
| description | Abstract At the Galapagos triple junction in the equatorial Pacific Ocean, the Cocos‐Nazca spreading center does not meet the East Pacific Rise (EPR) but, instead, rifts into 0.4 Myr‐old lithosphere on the EPR flank. Westward propagation of Cocos‐Nazca spreading forms the V‐shaped Galapagos gore. Since ~1.4 Ma, opening at the active gore tip has been within the Cocos‐Galapagos microplate spreading regime. In this paper, bathymetry, magnetic, and gravity data collected over the first 400 km east of the gore tip are used to examine rifting of young lithosphere and transition to magmatic spreading segments. From inception, the axis shows structural segmentation consisting of rifted basins whose bounding faults eventually mark the gore edges. Rifting progresses to magmatic spreading over the first three segments (s1–s3), which open between Cocos‐Galapagos microplate at the presently slow rates of ~19–29 mm/year. Segments s4–s9 originated in the faster‐spreading (~48 mm/year) Cocos‐Nazca regime, and well‐defined magnetic anomalies and abyssal hill fabric close to the gore edges show the transition to full magmatic spreading was more rapid than at present time. Magnetic lineations show a 20% increase in the Cocos‐Nazca spreading rate after 1.1 Ma. The near‐axis Mantle Bouguer gravity anomaly decreases eastward and becomes more circular, suggesting mantle upwelling, increasing temperatures, and perhaps progression to a developed melt supply beneath segments. Westward propagation of individual Cocos‐Nazca segments is common with rates ranging between 12 and 54 mm/year. Segment lengths and lateral offsets between segments increase, in general, with distance from the tip of the gore. |
| first_indexed | 2024-03-11T12:57:26Z |
| format | Article |
| id | doaj.art-4cf05fb896054936a4da0c4e44d216f0 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:57:26Z |
| publishDate | 2020-06-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-4cf05fb896054936a4da0c4e44d216f02023-11-03T16:56:04ZengWileyGeochemistry, Geophysics, Geosystems1525-20272020-06-01216n/an/a10.1029/2020GC008957The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading CenterDeborah K. Smith0Hans Schouten1Ross Parnell‐Turner2Emily M. Klein3Johnson Cann4Charles Dunham5Gabriella Alodia6Iker Blasco7Benjamin Wernette8Dominik Zawadzki9Elvira Latypova10Sara Afshar11Scott Curry12National Science Foundation Alexandria VA USAWoods Hole Oceanographic Institution Woods Hole MA USAScripps Institution of Oceanography University of California, San Diego La Jolla CA USADivision of Earth and Ocean Sciences Duke University Durham NC USASchool of Earth and Environment University of Leeds, UK and Curlew Cottage Penrith UKSchool of Earth and Environment University of Leeds Leeds UKSchool of Earth and Environment University of Leeds Leeds UKGeological Survey of Spain, Instituto Geológico y Minero de España Madrid SpainDivision of Earth and Ocean Sciences Duke University Durham NC USAInstitute of Marine and Environmental Sciences University of Szczecin Szczecin PolandDepartment of Regional Geology Saint Petersburg State University St Petersburg RussiaScripps Institution of Oceanography University of California, San Diego La Jolla CA USAWoods Hole Oceanographic Institution Woods Hole MA USAAbstract At the Galapagos triple junction in the equatorial Pacific Ocean, the Cocos‐Nazca spreading center does not meet the East Pacific Rise (EPR) but, instead, rifts into 0.4 Myr‐old lithosphere on the EPR flank. Westward propagation of Cocos‐Nazca spreading forms the V‐shaped Galapagos gore. Since ~1.4 Ma, opening at the active gore tip has been within the Cocos‐Galapagos microplate spreading regime. In this paper, bathymetry, magnetic, and gravity data collected over the first 400 km east of the gore tip are used to examine rifting of young lithosphere and transition to magmatic spreading segments. From inception, the axis shows structural segmentation consisting of rifted basins whose bounding faults eventually mark the gore edges. Rifting progresses to magmatic spreading over the first three segments (s1–s3), which open between Cocos‐Galapagos microplate at the presently slow rates of ~19–29 mm/year. Segments s4–s9 originated in the faster‐spreading (~48 mm/year) Cocos‐Nazca regime, and well‐defined magnetic anomalies and abyssal hill fabric close to the gore edges show the transition to full magmatic spreading was more rapid than at present time. Magnetic lineations show a 20% increase in the Cocos‐Nazca spreading rate after 1.1 Ma. The near‐axis Mantle Bouguer gravity anomaly decreases eastward and becomes more circular, suggesting mantle upwelling, increasing temperatures, and perhaps progression to a developed melt supply beneath segments. Westward propagation of individual Cocos‐Nazca segments is common with rates ranging between 12 and 54 mm/year. Segment lengths and lateral offsets between segments increase, in general, with distance from the tip of the gore.https://doi.org/10.1029/2020GC008957Galapagos triple junctionmid‐ocean ridgesseafloor spreadingGalapagos microplateplate boundaries |
| spellingShingle | Deborah K. Smith Hans Schouten Ross Parnell‐Turner Emily M. Klein Johnson Cann Charles Dunham Gabriella Alodia Iker Blasco Benjamin Wernette Dominik Zawadzki Elvira Latypova Sara Afshar Scott Curry The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center Geochemistry, Geophysics, Geosystems Galapagos triple junction mid‐ocean ridges seafloor spreading Galapagos microplate plate boundaries |
| title | The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center |
| title_full | The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center |
| title_fullStr | The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center |
| title_full_unstemmed | The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center |
| title_short | The Evolution of Seafloor Spreading Behind the Tip of the Westward Propagating Cocos‐Nazca Spreading Center |
| title_sort | evolution of seafloor spreading behind the tip of the westward propagating cocos nazca spreading center |
| topic | Galapagos triple junction mid‐ocean ridges seafloor spreading Galapagos microplate plate boundaries |
| url | https://doi.org/10.1029/2020GC008957 |
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