Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication]

Details Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication] Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication]

Dec 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005e%26psl.240..642b&link_type=abstract

Earth and Planetary Science Letters, Volume 240, Issue 3-4, p. 642-655.

Physics

4

Scientific paper

The Vema Transverse Ridge (VTR) is a prominent, long and narrow topographic anomaly that runs for over 300 km along a sea floor spreading flow line south of the Vema transform at 11° N in the Atlantic. It rises abruptly about 140 km from the axis of the Mid-Atlantic Ridge (MAR) in ˜10 Myr old crust and runs continuously up to ˜25 Myr old crust. It reaches over 3 km above the predicted lithospheric thermal contraction level. It is absent in crust younger than 10 Myr; thus, the uplift of the VTR must have ended roughly 10 Ma. The VTR is interpreted as the exposed edge of a flexured and uplifted slab of oceanic lithosphere that was generated at an 80 km long MAR segment. Based on satellite gravimetry imagery this MAR segment was born roughly 50 Ma and increased its length at an average rate of 1.6 mm/yr. Multibeam data show that the MAR-parallel sea floor fabric south of the VTR shifts its orientation by 5° to 10° clockwise in ˜11 12 Myr old crust, indicating a change at that time of the orientation of the MAR axis and of the position of the Euler rotation pole. This change caused extension normal to the transform, followed between 12 and 10 Ma by flexure of the edge of the lithospheric slab, uplift of the VTR at a rate of 2 to 4 mm/yr, and exposure of a lithospheric section (Vema Lithospheric Section or VLS) at the northern edge of the slab, parallel to the Vema transform. Ages of pelagic carbonates encrusting ultramafic rocks sampled at the base of the VLS at different distances from the MAR axis suggest that the entire VTR rose vertically as a single block within the active transform offset. A 50 km long portion of the crest of the VTR rose above sea level, subsided, was truncated at sea level and covered by a carbonate platform. Subaerial and submarine erosion has gradually removed material from the top of the VTR and has modified its slopes. Spreading half rate of the crust south of the transform decreased from 17.2 mm/yr between 26 and 19 Ma to ˜16.9 mm/yr between 19 and ˜10 Ma, to ˜13.6 mm/yr from 10 Ma to present. The slowing down of spreading occurred close in time to the change in ridge/transform geometry, suggesting that the two events are related. A numerical model relates lithospheric flexure to extension normal to the transform, suggesting that the extent of the uplift depends on the thickness of the brittle layer, consistent with the observed greater uplift of the older lithosphere along the VTR.

Affiliated with

Also associated with

No associations

Rating

Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication] does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication], we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [rapid communication] will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1430278