Help for PetDB

Setting constraints on a sample selection

The database contains chemical data for rock samples including volcanic, intrusive and metamorphic and mantle rocks. Most samples are either mid-ocean ridge basalts, abyssal peridotites, or mantle xenoliths, but PetDB also contains data for samples from other tectonic settings.

To query the database for chemical values, you first need to select samples in which you are interested. The following criteria can be used (you can use one criteria or a combination of criteria):

  • LATITUDE/LONGITUDE: Enter latitude and/or longitude of the geographical area you are interested in. Enter the Northern and Southern bounding latitudes (latitudes on the southern hemisphere need to be entered as negative values, e.g. 9.6°S = -9.6) and the Western and Eastern longitudes (Western longitudes need to be entered as negative values, e.g. 112°W = -112).
     
  • LOCATION: Use geographical names define a specific geographical area for your sample selection. Geographical names are used on various regional scales ranging from name of a volcanic province to volcano type or the name of an orogenic belt.
     
  • TECTONIC SETTING: Use this criterion if you are interested in samples from one or more specific tectonic settings such as 'SPREADI'INTRAPLATE_CRATON', 'CONVERGENT_MARGIN', or 'CONTINENTAL_RIFT'.
     
  • SAMPLE CHARACTERISTICS: You can define your sample selection by rock type (e.g. 'basaltic', 'alkaline', 'xenolith'), by degree of alteration*. When you click on a rock type, you will see a list rock classes in the selection box. It is important to note that the classification of samples into these 'rock classes' is based on information provided in publications and is NOT done by EarthChem.
    You can select samples based on their degree of alteration. NOTE that information on degree of alteration is provided only for a minority of samples in EarthChem due to lack of this information in publications. Selecting only 'fresh' samples will ensure that the data you get were actually measured on fresh samples, but you might miss data for fresh samples just because there was no information on alteration in the data publication.

 

  • CRUISE/SHIP:  This option allows you to get data for samples that have been collected on a specific cruise/expedition. Use a cruise name to select the samples collected on this cruise. In case you don't know the cruise name, you can use the ship name and the cruise year. You can also query by the name of the chief scientist or the name of the organizing institution. Note: Many cruises in PetDB are listed without the chief scientist or the organizing institution, so there might be only few records returned when you use these criteria.
     
  • PUBLICATION INFORMATION: The option 'Set Publication Information' allows you to find specific publications in PetDB and view and download data tables from the publication* (click on 'data tables' in the list of references that is returned when you submit a query for publications by author(s), year(s), keyword(s), etc.). Once you see a list of references, you can select any of these to define the group of samples for which you want data by clicking on 'APPLY'. Applying selected references to your sample search will allow you to find all chemical data for these samples available from multiple references. Note: The data tables contain only original values, any referenced values can only be found in the original publication.
     
  • DATA AVAILABILITY: Use a query by data availability if you are looking for data from samples for which specific data types have been published. For example, if you are interested to get data for only those samples for which major elements AND olivine analyses are available, you click on the appropriate check boxes here.
     
  • SAMPLE NAME: You can find samples by the name that is reported in the publication ('ALIAS'), or by the PetDB unique sample identifier. As many names in publications are non-unique (e.g. D5-1), you will often get multiple results. You need to check the sample information by clicking on the sample identifier to decide which sample is the correct one.
  • TAG-ALONG DATA: Once you have made your data selection in terms of material and analytes, note that there is an option to include "Tag-along data". This allows the user to get additional analytical items for teh chosen samples. For example, if you originally only selected all major elements and are ready to downlaod data, there is an option to include tag-along data of other analytes rather than going back and redoing the original search.

Downloading: Pre-Compiled Data vs. Individual Analyses

Individual analyses

This option will return a data table that contains all analytical values available for the samples and for the chemical parameters you selected organized by reference and method. This means that each individual row of the result table will contain only those analytical values for a sample that were analyzed with the same method and reported in same reference.

If you select 'Individual Analyses', you will get a table that lists all analyses available for the samples and for the chemical items you selected organized by reference and method. If multiple measurements have been made for a certain chemical item on the same sample (e.g. Nb measured by different methods and published in different papers), they will all be listed in the table. One row in the data table will only contain values from one publication and only data acquired by the same method. A table with individual analyses will generally report data for the same sample in multiple rows.

Sample Majors H2O Nb Rb Sr 87Sr/86Sr 143Nd/144Nd Method Ref
A XX             XRF 1
B YY             XRF 1
C ZZ             XRF 1
A   0.5           WET 1
B   0.4           WET 1
C   0.7           WET 1
A     0.3 2 98     ICP-MS 2
B     0.6 1.5 76     ICP-MS 2
C     0.5 1.7 82     ICP-MS 2
A           0.70305 0.51211 MS 3
B           0.70298 0.51193 MS 3
C           0.70311 0.51205 MS 3
A       1.98 96.8     MS-ID 3
B       1.45 74.2     MS-ID 3
C       1.80 83.5     MS-ID 3

Pre-compiled

This option will return a data table with only one row for each sample that contains a compilation of analytical values measured by different methods or reported in different references. If multiple values for the same chemical parameter exist, one of the values is selected on the basis of rules that we established (see below).

Example: You selected to get major elements, Nb, Rb, and Sr concentrations , and Sr and Nd isotope ratios for samples A,B, and C. Major elements analyzed by XRF and wet chemistry for these samples were published in reference 1, the trace elements analyzed by ICP-MS in reference 2, isotope ratios by mass spectrometry and Sr and Rb by isotope dilution MS in reference 3.

Sample Majors H2O Nb Rb Sr 87Sr/86Sr 143Nd/144Nd Method Ref
A XX 0.5 0.3 1.98 96.8 0.70305 0.51211 XRF,etc 1,2,3
B YY 0.4 0.6 1.45 74.2 0.70298 0.51193 XRF,etc 1,2,3
C ZZ 0.7 0.5 1.80 83.5 0.70311 0.51205 XRF,etc 1,2,3

Rules of Data Selection for Pre-Compilation

For isotope ratios:

  1. Publication year is compared. The latest value has the highest priority
  2. If there is more than one value published in the latest year, standard deviation is used as criteria.

For major elements, rare earth elements and other trace elements:

  1. Method: choose the values with highest method priority.
  2. If there is more than one value done by the same method (and which has the highest priority among all analyses for that element of that sample), then publication year is compared. The latest value has the highest priority

Method: listed below with priority from high to low.

Major elements:

  • XRF: X-RAY FLUORESCENCE
  • DCP: DIRECT CURRENT PLASMA
  • WET: WET CHEMISTRY
  • EMP: ELECTRON MICROPROBE
  • ES: EMISSION SPECTROMETRY
  • Other

Rare earth elements:

  • MS-ID: ISOTOPE DILUTION MASS SPECTROMETRY
  • MS: MASS SPECTROMETRY
  • ICPMS: INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY
  • DCP: DIRECT CURRENT PLASMA
  • SSMS: SPARC SOURCE MASS SPECTROMETRY
  • INAA: INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS
  • Other

Other trace elements:

  • MS-ID: ISOTOPE DILUTION MASS SPECTROMETRY
  • MS: MASS SPECTROMETRY
  • ICPMS: INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY
  • SSMS: SPARC SOURCE MASS SPECTROMETRY
  • XRF: X-RAY FLUORESCENCE
  • DCP: DIRECT CURRENT PLASMA
  • INAA: INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS
  • AAS: ATOMIC ABSORPTION
  • Other