10.1594/PANGAEA.717819
Bralower, Timothy J
Timothy J
Bralower
0000-0002-3503-859X
Fullagar, Paul D
Paul D
Fullagar
Paull, Charles K
Charles K
Paull
Dwyer, Gary S
Gary S
Dwyer
Leckie, R Mark
R Mark
Leckie
0000-0002-7311-2180
Depth, age, strontium isotopic ratios and trace elemental ratios of samples from thirteen DSDP and ODP holes
PANGAEA
1997
Drilling/drill rig
Leg26
Leg36
Leg44
Leg51
Leg52
Leg71
Leg79
Leg80
Leg103
Leg122
Glomar Challenger
Joides Resolution
Deep Sea Drilling Project (DSDP)
Ocean Drilling Program (ODP)
1972-10-25T00:00:00/1988-08-11T21:00:00
en
Supplementary Publication Series of Datasets
10.1130/0016-7606(1997)109<1421:MCSISO>2.3.CO;2
ftp://rock.geosociety.org/pub/reposit/1985/8514.pdf
13 datasets
application/zip
Creative Commons Attribution 3.0 Unported
Large variations exist between published mid-Cretaceous (late Barremian to early Turonian stages) seawater Sr-isotope stratigraphies; this has resulted in disparate interpretations of crustal production rates. We report on a detailed investigation of seawater Sr-isotope stratigraphy based on foraminifers and, where available, on inoceramid bivalves from 12 mid-Cretaceous Deep Sea Drilling Project and Ocean Drilling Program sections. The effects of diagenesis are assessed using scanning electron microscope observations and trace-elemental analyses, but are best distinguished by comparing the 87Sr/86Sr values of similar-age samples from different sites. Strontium-isotope analyses compiled from 9 of 12 sites that have detailed age control define one band of common values. This band is used as a composite curve, which presumably represents seawater 87Sr/86Sr values. The composite curve shows a "trough" of markedly lower 87Sr/86Sr values in the Aptian and early Albian stages, higher but constant values for the middle Albian-Cenomanian stages, followed by a decrease in 87Sr/86Sr values in the early Turonian.
Variations between published mid-Cretaceous Sr-isotope records result from diagenetic alteration, analytical problems, and the diverse biostratigraphic approaches and assumptions used to estimate sample ages. When preexisting age data are made consistent, the composite record shows close similarities with data sets derived from measurements of macrofossils in land sections of Europe and North America.
The interval of decreased 87Sr/86Sr values in the Aptian-Albian stages overlaps with the pulse of mid-plate volcanic activity that produced the Ontong Java, Manihiki, and Kerguelen Plateaus. The exact age and the shape of the trough, however, are consistent with increased spreading rates at oceanic ridges, given the existing data on the timing of mid-plate volcanic activity.
Supplement to: Bralower, Timothy J; Fullagar, Paul D; Paull, Charles K; Dwyer, Gary S; Leckie, R Mark (1997): Mid-Cretaceous strontium-isotope stratigraphy of deep-sea sections. Geological Society of America Bulletin, 109(11), 1421-1442
-76.178
112.4737
-51.0047
48.9107
Indian Ocean//PLATEAU
South Atlantic/PLATEAU
North Atlantic
North Atlantic/CONT RISE
North Atlantic/PLATEAU
North Atlantic/ESCARPMENT
South Atlantic Ocean
South Indian Ridge, South Indian Ocean