Expedition 390/393 Scientific Prospectus: The South Atlantic Transect

Coggon, Rosalind M.; Christeson, G. L.; Sylvan, Jason B.; Teagle, D.A.H.; Estes, Emily R.; Williams, T.; Zarikian, C.A. Alvarez

doi:10.14379/iodp.sp.390393.2020

Cited by 7 publications

(17 citation statements)

References 103 publications

(103 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…F4). A reflector at ~6.56 s TWT was interpreted to be the top of basement at 126 mbsf (Coggon et al, 2020). This site is located 13 nmi north of Site U1556, and the basement at both sites is predicted to have formed F7).…”

Section: Principal Resultsmentioning

confidence: 99%

“…We lowered the thrusters and entered DP mode at 0349 h. The APC/XCB BHA was made up and lowered to the seafloor. Based on the seafloor reflection in the seismic profile, the water depth at Site U1561 was expected to be 4857 mbsl (Coggon et al, 2020). As we arrived on site, the precision depth recorder (PDR) 3.5 kHz signal malfunctioned and the depth reading had to be taken with the 12.5 kHz signal instead, which gave an apparent water depth of 4963 mbsl (106 m deeper than the depth in the Scientific Prospectus [Coggon et al, 2020]).…”

Section: Principal Resultsmentioning

confidence: 99%

“…Site U1560 is located on Seismic Line CREST02 at common depth point (CDP) 12770, ~400 m south of the CREST1E crossing line. A reflector at ~5.08 s two-way traveltime (TWT) was interpreted to be the top of basement and estimated to be 104 mbsf (Coggon et al, 2020). Based on the deeper-than-expected basement depths we found during Expedition 390C, we expected basement to be similarly deeper at Site U1560.…”

Section: Background and Objectivesmentioning

confidence: 94%

“…Site U1556 is in the central South Atlantic Ocean at 30.6°S at a water depth of 5006 m, ~1250 km west of the MAR. It lies on Seismic Line CREST1A/B at CDP 3410 near the CREST05 crossing line (Figure F4) (Coggon et al, 2020). A reflector at ~6.9 s TWT was interpreted to be the top of basement and was found at 278 mbsf in Hole U1556A.…”

Section: Background and Objectivesmentioning

confidence: 96%

See 3 more Smart Citations

Expedition 395E Preliminary Report: Complete South Atlantic Transect Reentry Systems

Williams¹,

Estes²,

Rhinehart³

et al. 2021

International Ocean Discovery Program Preliminary Report

Self Cite

View full text Add to dashboard Cite

International Ocean Discovery Program (IODP) Expeditions 390C and 395E were implemented in response to the global COVID-19 pandemic and occupied sites proposed for the postponed Expeditions 390 and 393, South Atlantic Transect 1 and 2. Expedition 395E completed most of the preparatory work that Expedition 390C did not have time to complete. The overall objective of Expeditions 390C and 395E was to core one hole at each of the South Atlantic Transect sites with the advanced piston corer/extended core barrel (APC/XCB) system to basement for gas safety monitoring and to install a reentry system with casing through the sediment to a few meters into basement in a second hole.Expedition 395E started in Cape Town, South Africa, and ended in Reykjavík, Iceland, after 20 days of on-site operations. We cored to basement at two new sites, U1560 and U1561, and completed reentry systems at three sites, U1556, U1557, and U1560. These operations will expedite basement drilling during the rescheduled Expeditions 390 and 393.Hole U1560A (Proposed Site SATL-25A) lies in ~15.2 Ma crust and is composed of carbonate-rich sediments to 120 meters below seafloor (mbsf ) and 2.5 m of underlying basalt. A reentry system was deployed in Hole U1560B to 122.0 mbsf. We then moved to the sites at the western end of the transect on ~61 Ma crust. In Hole U1557D, 10¾ inch casing was deployed to 571.6 mbsf to deepen the 16 inch casing that was deployed during Expedition 390C, and in Hole U1556B, a reentry system was deployed to 284.2 mbsf. The remaining operations time was insufficient to install a reentry system at the originally planned site, Proposed Site SATL-33B. Instead, we cored Hole U1561A (Proposed Site SATL-55A) to 47 mbsf. It is composed of red clay and carbonate ooze overlying 3 m of basalt.The six primary sites of the South Atlantic Transect lie perpendicular to the Mid-Atlantic Ridge on the South American plate, overlying crust ranging in age from 7 to 61 Ma. Basement coring will increase our understanding of how crustal alteration progresses over time across the flanks of a slow/intermediate-spreading ridge and how microorganisms survive in deep subsurface environments. Sediment will be used in paleoceanographic and microbiological studies.

show abstract

Section: Principal Resultsmentioning

confidence: 99%

Section: Principal Resultsmentioning

confidence: 99%

Section: Background and Objectivesmentioning

confidence: 94%

Section: Background and Objectivesmentioning

confidence: 96%

See 2 more Smart Citations

Expedition 395E Preliminary Report: Complete South Atlantic Transect Reentry Systems

Williams¹,

Estes²,

Rhinehart³

et al. 2021

International Ocean Discovery Program Preliminary Report

Self Cite

View full text Add to dashboard Cite

show abstract

“…The original operational strategy for Expeditions 390 and 393 is described in detail in the Scientific Prospectus (Coggon et al, 2020) and was updated in the Scientific Prospectus Addendum (Coggon et al, 2022) following the completion of engineering Expeditions 390C and 395E. In brief, the SAT intended to drill six sites located at five different crustal ages (~7, 15, 31, 49, and 61 Ma), with two of the sites located in the same localized sedimentary basin on 61 Ma crust where significant basement topography results in variable sediment thickness (~180 and 640 m thick at proposed Sites SATL-53B and SATL-54A, respectively).…”

Section: Operational Strategymentioning

confidence: 99%

Expedition 390 Preliminary Report: South Atlantic Transect 1

Coggon¹,

Sylvan²,

Teagle³

et al. 2022

International Ocean Discovery Program Preliminary Report

View full text Add to dashboard Cite

The South Atlantic Transect (SAT) is a multidisciplinary scientific ocean drilling project that comprises four International Ocean Discovery Program (IODP) expeditions: engineering Expeditions 390C and 395E as well as Expeditions 390 and 393. Altogether, the expeditions aim to recover complete sedimentary sections and the upper 100-350 m of the underlying oceanic crust along a slow/intermediate spreading rate Mid-Atlantic Ridge crustal flow line at ~31°S. The sediments along this transect were originally spot cored more than 50 y ago during Deep Sea Drilling Project Leg 3 (December 1968-January 1969 to help verify the theories of seafloor spreading and plate tectonics. Given dramatic advances in drilling technology and analytical capabilities since Leg 3, many high-priority scientific objectives can be addressed by revisiting the transect. The SAT expeditions target six primary sites on 7, 15, 31, 49, and 61 Ma ocean crust, which fill critical gaps in our sampling of intact in situ ocean crust with regards to crustal age, spreading rate, and sediment thickness. Drilling these sites is required to investigate the history of the low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean and quantify past hydrothermal contributions to global biogeochemical cycles. Samples from the transect of the previously unexplored sediment-and basalt-hosted deep biosphere beneath the South Atlantic Gyre are essential to refining global biomass estimates and examining microbial ecosystems' responses to variable conditions in a low-energy gyre and aging ocean crust. The transect is located near World Ocean Circulation Experiment Line A10, providing access to records of carbonate chemistry and deepwater mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO 2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deepwater formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change and the effects of tectonic gateways and climate on ocean acidification.Engineering Expeditions 390C and 395E cored a single hole through the sediment/basement interface with the advanced piston corer/extended core barrel system at five of the six primary proposed SAT sites and installed a reentry system with casing either into basement or within 10 m of basement at each of those five sites. Expedition 390 (7 April-7 June 2022) conducted operations at three of the SAT sites, recovering 700 m of core (77% recovery) over 30.3 days of on-site operations. Sediment coring, basement drilling, and logging were conducted at two sites on 61 Ma crust, and sediment coring was completed at the 7 Ma crust site. At Site U1557 on 61 Ma crust, the drill bit was deposited on the seafloor prior to downhole logging, leaving Hole U1557D available for future deepening and to establish a legacy borehole for basement hydrothermal and mi...

show abstract

Expedition 393 Preliminary Report: South Atlantic Transect 2

Teagle¹,

Reece²,

Coggon³

et al. 2023

International Ocean Discovery Program Preliminary Report

Self Cite

View full text Add to dashboard Cite

The South Atlantic Transect (SAT) is a multidisciplinary scientific ocean drilling experiment designed to investigate the evolution of the oceanic crust and overlying sediments across the western flank of the Mid-Atlantic Ridge. This project comprises four International Ocean Discovery Program expeditions: fully staffed Expeditions 390 and 393 (April-August 2022) built on engineering preparations during Expeditions 390C and 395E that took place without science parties during the height of the Coronavirus Disease 2019 (COVID-19) pandemic. Through operations along a crustal flow line at ~31°S, the SAT recovered complete sedimentary sections and the upper ~40-340 m of the underlying ocean crust formed at a slow to intermediate spreading rate at the Mid-Atlantic Ridge over the past ~61 My. The sediments along this transect were originally spot cored more than 50 y ago during Deep Sea Drilling Project Leg 3 (December 1968-January 1969 to help verify the theories of seafloor spreading and plate tectonics.The SAT expeditions targeted six primary sites on 7, 15, 31, 49, and 61 Ma ocean crust that fill critical gaps in our sampling of intact in situ ocean crust with regards to crustal age, spreading rate, and sediment thickness. Drilling these sites was required to investigate the history, duration, and intensity of the low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean. This knowledge will improve the quantification of past hydrothermal contributions to global biogeochemical cycles and help develop a predictive understanding of the impacts of variable hydrothermal processes and exchanges. Samples from the transect of the previously unexplored sediment-and basalt-hosted deep biosphere beneath the South Atlantic Gyre are essential to refine global biomass estimates and examine microbial ecosystems' responses to variable conditions in a low-energy gyre and aging ocean crust.The transect is located near World Ocean Circulation Experiment Line A10, which provides a baseline for records of carbonate chemistry and deepwater mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO 2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deepwater formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change and the effects of tectonic gateways and climate on ocean acidification.During engineering Expeditions 390C and 395E, a single hole was cored through the sediment cover and into the uppermost rocks of the ocean crust with the advanced piston corer (APC) and extended core barrel (XCB) systems at five of the six primary proposed SAT sites. Reentry systems with casing were then installed either into basement or within 10 m of basement at each of those five sites. Expedition 390 (7 April-7 June 2022) conducted operations at three of the SAT sites, recovering 700 m of core (77%) over 30...

show abstract

Expedition 390/393 Scientific Prospectus: The South Atlantic Transect

Cited by 7 publications

References 103 publications

Expedition 395E Preliminary Report: Complete South Atlantic Transect Reentry Systems

Expedition 395E Preliminary Report: Complete South Atlantic Transect Reentry Systems

Expedition 390 Preliminary Report: South Atlantic Transect 1

Expedition 393 Preliminary Report: South Atlantic Transect 2

Contact Info

Product

Resources

About