SPECMAP Archive #4: Specmap4.readme
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               World Data Center A- Paleoclimatology
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NOTE: PLEASE CITE ORIGINAL REFERENCES WHEN USING THIS DATA!!!!!


NAME OF DATA SET:  SPECMAP Archive #4
LAST UPDATE: 11/93  (Original receipt date by WDC-A Paleo) 
CONTRIBUTORS:  John Imbrie, Angeline Duffy, Brown University
IGBP PAGES/WDCA Data Contribution Series #:  93-031

SUGGESTED DATA CITATION: 
Imbrie, J., et al, 1993, SPECMAP Archive #4.  IGBP PAGES/World Data Center-A for Paleoclimatology
Data Contribution Series # 93-031.  NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

ORIGINAL REFERENCE:
'On the Structure and Origin of Major Glaciation Cycles: part 2', 
Imbrie et al., PALEOCEANOGRAPHY, Dec., 1993.

GEOGRAPHIC REGION: Global
PERIOD OF RECORD: 0 - 400,000 YBP
LIST OF FILES: 47 data files.  See the file Archive4.con for descriptions.

DESCRIPTION:
     This archive contains files of the time series appearing               
in 'On the Structure and Origin of Major Glaciation Cycles: part 2',        
Imbrie et al., PALEOCEANOGRAPHY, Dec., 1993 (hereafter part 2).             
If a time series is contained in SPECMAP Archive 2 it is not repeated       
here.  No spectra are included, as most investigators would prefer          
to do their own analysis using the files in this archive.  However,         
filtered components of time series are included.                            
                                                                            
     One time series given in Archive 2 is repeated here (cadmium/          
calcium ratio for CHN82-24) to aid in identification of a section           
of the core where species abundance was low.  The section extends           
from adjusted depth 415cm to 436cm, with corresponding ages from            
118ka to 124ka.  The section includes seven data points.                    
                                                                            
     Fig 3 of part 2 shows a long benthic del O-18 record, ODP677,          
patched to a stacked benthic del O-18 series.  The values younger           
than 400ka are taken from the latter series, while all values older         
than 400ka are from ODP677.  In the file, the core identification           
(the first twelve characters) identifies the source of the del O-18         
value.  For some del O-18 values, -9999 appears, indicating a gap           
in the data.                                                                
                                                                            
     The benthic stack Fig 3 part 2, is a composite of del O-18             
values from seven sites, IOS 82, ODP 677, V19-27, RC13-110, V19-30,         
site 607, DSDP 552.  All except IOS 82 are displayed in Fig 5, 'On          
the Structure and Origin of Major Glaciation Cycles: part 1', Imbrie        
et al., PALEOCEANOGRAPHY, Dec., 1992 (hereafter part 1), and found          
in Archive 2.  The IOS 82 data are given here with the other files          
for Fig 3.  Four of the records go beyond 600ka, while the other            
three are shorter.  A Gaussian stacking method was used to                  
estimate smoothed del O-18 values every two kyrs.  From all seven           
cores raw data values and their ages were combined into one large           
file.  All del O-18 values with ages within +/- 5kyrs of a                  
particular time were given a weight corresponding to their                  
position within a Gaussian filter (6 sigma = 10kyrs) centered at            
at that time.  For each time a weighted mean was calculated.  The           
standard deviation from the mean is included for each estimate.  The        
whole stack is included here although only the first 200 values             
are used in Fig 3, part 2.                                                  
                                                                            
     The files in Archive 4 are listed in file archive4.con.
They are identified by the figure in part 2 where they appear.  
It is important that the user have a copy of this publication 
in hand,  as a terse description is all that is given.