LA-ICP-MS Laboratory

The laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) facility at GEUS is designed to address different problems in Earth Sciences through the generation of isotopic, elemental and U-Th-Pb geochronology information.

 

The main purpose of this facility is to:

  • offer researchers, companies, students and organizations to use our expertise and instrumentation to address problems in Earth and other sciences.
  • develop new applications of laser ablation ICP mass spectrometry for basic research and applied science.
  • provide researchers and students the opportunity to obtain “hands-on” experiences with the LA-ICP-MS analytical techniques used while acquiring data.

Key Instruments

The facility operates an Element 2 single-collector magnetic sector field inductively coupled plasma mass spectrometer (SF-ICP-MS) from Thermo-Fisher Scientific that is connected to a NWR213 laser ablation system from esi/New Wave Research.

 

Key instrument capabilities:

  • Quantitative analyses can be obtained for most elements in the mass range from 7Li to 238U.
  • Low ppm level trace element determinations in most solid materials at spatial resolutions of 15 to 150 microns (spot or line).
  • Detection limits in the order of ppb to a few ppm
  • Laser beam diameters of 5-150 µm

 

Types of analyses

The LA-ICP-MS facility at GEUS mainly performs U-Th-Pb age determination of accessory minerals and trace element analysis of mineral grains and bulk geological samples. Types of analyses carried out are:

 

Zircon U-Pb geochronology
Analyses are performed on a routine basis for detrital zircon provenance analysis, formation ages of magmatic and metamorphic rocks, structural and tectonic framework studies and for ore formation investigations. Where core-rim (or other significant growth domains) is observed it is sometimes possible to obtain multiple ages representing events recorded in the core or rim of a single crystal. Analyses are typically performed on mineral separates embedded in epoxy mounts or on thin sections (typically 30-100 µm thick).

Analyses are performed on a routine basis for detrital zircon provenance analysis, formation ages of magmatic and metamorphic rocks, structural and tectonic framework studies and for ore formation investigations. Where core-rim (or other significant growth domains) is observed it is sometimes possible to obtain multiple ages representing events recorded in the core or rim of a single crystal. Analyses are typically performed on mineral separates embedded in epoxy mounts or on thin sections (typically 30-100 µm thick).


Trace elements concentration

Determination of the trace (and some major) elements abundances and ratios in single minerals or bulk rock compositions are performed on a routine basis. We specialize in the analysis of inorganic materials, naturally occuring materials as well as synthetic materials, e.g.:

  • rocks
  • minerals
  • gem stones
  • carbonate materials (e.g. otoliths, shells)
  • some synthetic materials (glasses, ceramics, pressed powder pellets)

Analysis of almost any solid material is in principle possible to analyze by LA-ICP-MS, but the following materials are not routinely performed at GEUS: metals including sulfide minerals, bones, teeth, paints and plastics, soft tissues and hair.

NB: Major element composition is used as internal standard for concentration determinations. Thus, to quantify data the concentration of at least one major element constituent (e.g. Si, Ca or Mg) that is to be used as internal standard must be known prior to laser analysis. Typically, this is obtained by electron probe micro-analysis (EPMA), XRF or akin technique.


U-Th-Pb multi-phase geochronometry

Dating of accessory minerals (other than just zircon) is a powerful tool for understanding geological processes that may not be recorded in the zircons, e.g. metamorphic or hydrothermal events or the provenance of sediments derived from metamorphic terrains. Thus, we offer U-Th-Pb dating analyses of the mineral phases:

  • Rutile
  • Titanite
  • Baddeleyite
  • Xenotime
  • Monazite

Analyses are performed on request and can include one (single phase dating) or several (multi-phase dating) of the minerals listed above. Please consult the laboratory staff for further information. We are always open to requests concerning dating of other mineral than listed here.


Fluid inclusion analyses (development stage)

When minerals crystallize from a melt or a fluid phase, relics are commonly trapped and preserved as fluid (or melt) inclusions several micrometers in size. Such inclusions are a main source of chemical information about e.g. late-stage magma crystallization, crustal fluid flow, hydrothermal transport processes and ore formation, and can be analyzed by LA-ICP-MS. At present we are developing and testing procedures for the quantitative chemical analysis of such inclusions.

 

Sample preparation for LA-ICP-MS analysis


Preparation by GEUS staff:

We have extensive experience in preparing samples in our sample preparation laboratories from crushing of the raw rock material to the fabrication of polished mounts. Available mineral separation techniques include heavy liquid separation, water-shaking table, Frantz electro-magnetic separator and high-quality picking microscopes. External users can bring prepared samples (please consult the staff for details).


Sample types and size:

Our different sample holders offer a number of options for mounting sample material of different size and shape. In most cases the sample material is prepared by mounting mineral grain separates in standard 1” epoxy mounts or as petrographic thin or thick sections for in-situ analysis.Sample sizes that can be accommodated:

  • Round mounts of 10, 25 (1”), 30 and 40 mm in diameter
  • Standard size (ca. 20x30 mm) thin or thick sections
  • Odd sized and shaped samples of <80 mm in size may be accommodated. please ask for further information.
  • Coating: Materials to be analyzed must be dry, cleaned and free of any kind of coating (e.g. carbon, gold, etc.). Any carbon coating from previous microprobe analysis should be removed. Gold coating must be removed thoroughly as residues of gold coating can severely affect LA-ICP-MS data quality.


Polishing: Preferably, the surface of the material should be sufficiently polished. Samples do not need to have surface preparation, but data quality improves considerably if the samples are polished.


Imaging:

The microscope on the laser instrument is not as good as some of the dedicated microscopes one might be accustomed to, and locating specific spots to analyze can be tricky and time-consuming, in particular on polished sections and for fluid inclusions. Thus, prior to analysis users are strongly encouraged to bring along “sample map” images that will help maneuvering on the surface of the sample. For polished sections optical microscopy images are often required in addition to e.g. BSE, CL or equivalent imaging. Pen markings should be on the lower (glass) side of the thin sections because the section side is cleaned before analysis.

 

Data processing

Appropriate software is available for the data reduction of all types of LA-ICP-MS analyses performed. It is possible for external users to carry out their own analytical work and subsequent data reduction after receiving appropriate training by our experienced laboratory staff.

 

Prices

Please contact the laboratory manager for information.

 

Location

Department of Petrology and Economic Geology, area 3, room 2-335.