DOI: 10.25921/r26b-jy34
title: NOAA/WDS Paleoclimatology - Atlantic and Pacific Foraminiferal Amino Acid Racemization Data

description: Isoleucine, one of several amino acids isolated from a suite of 
well-dated deep-sea cores, shows a progressive increase in the 
degree of racemization with the age of the sediment. Amino acids 
in sediments show an initial rate of racemization almost an order 
of magnitude faster than the rate observed for free amino acids 
at a comparable pH and temperature. The observed kinetics depend 
on a variety of diagenetic processes, but it appears that the 
ratio of alloisoleucine to isoleucine is a reliable indicator 
of age for samples less than 400,000 years old; for older samples 
the results are more ambiguous. Isoleucine is racemic in samples 
older than about 15 million years.
description: Concentration and D-alloisoleucine/L-isoleucine values from mixed 
foraminfera samples from sediment cores from Atlantic, Caribbean, 
and Pacific basins. 	 

Core Locations:

Core              Latitude   Longitude WaterDepth(m)  OceanBasin
V12-122             17.00     -74.47       2730          A
A179-4              16.60     -74.80       2965          A
V16-205             15.40     -43.40       4045          A
V16-39             -24.72      -4.75       4510          A
V12-18             -28.70     -34.50       2935          A
RC8-93             -29.37     -105.23      3157          P
V23-110             17.63     -45.87       3746          A
CH96-G12            30.27     -43.32       4014          A
V24-28              15.32     -77.95       2274          A
RC5-12              26.58     -56.48       5104          A
A167-21             29.82     -76.58       1455          A
V18 BBD 2          -17.93     -154.13       800          P

JOIDES
Leg 7, site 62-1    1.867     141.93       2591          P
Leg 7, site 64-1    -1.73     158.60       2052          P
Leg 6, site 47-2    32.45     157.72       2689          P



LABORTAORY AND ANALYTICAL INFORMATION
Lab history                Lamont-Doherty Geological Observatory (LDGO) and Carnegie Institution of Washington, Geophysical Laboratory  (GL CIW)
Lab PI                     J. F. Wehmiller and P. E. Hare
Preparation date           1969-1970
Pretreatment               Sieve >74 µm, repeated sonication, distilled water wash  (see "Sonication")
AA  fraction               = AMINO FRACTION
Hydrolysis procedure       22 or 46 hr at 110°C in 6 M HCl under N2  (see "Hydrolysis time")
Bleach                     No
Analytical method          High pressure ion exchange liquid chromatography   (IELC)
Instrumental programming   Buffer gradient; concentrations based on separate chromatograms of standards
Area or height ratio       Area
Blank corrections          none
Response factors           none
Data screening criteria    none
Interlab comparisons       none

SAMPLE LOCATION INFORMATION
Country or ocean           Atlantic, Pacific
State or province or sea   Caribbean
Locality descriptors       = AREA
Lat (°)                    = LAT (°N)
Lon (°)                    = LON (°W)
Coordinate precision
Datum
Elevation, m               = WATER DEPTH (m)
Elevation precision

SAMPLE MATERIAL AND CONTEXT
Material type              = SAMPLE TYPE
Genus
Species
Number of individuals
Field context              marine
Field context              core
Field context              stratified section
Collection date
Collector                  Wehmiller
Sample PI                  Wehmiller
Stratigraphic unit or age
Numerical age              = APPROX AGE, Ma
Field ID                   = SITE NAME
Field ID 1                 = CORE DEPTH (cm)
Field ID 2
Sample ID
Fraction of shell
Sample position

RESULTS
Lab code                   GL CIW
Lab ID                     = Core, depth
Number of chromatograms    1
Sample or analytical qualitsee reference
AI                         = Alloisoleucine/Isoleucine
Free field 1               = Alloisoleucine, nmole/gm
Free field 2               = Isoleucine, nmole/gm
Free field 3               = Hydrolysis time
Free field 4               = Sonication