Spider diagram: primitive-mantle-normalized multi-element patterns

What a spider diagram shows

Elements are arranged from the most incompatible on the left to the least incompatible on the right, so a smooth pattern indicates simple melting and crystallization, while peaks and troughs point to specific processes or sources.

Classic signals include the negative Nb–Ta anomaly and positive Pb anomaly of subduction-related magmas, Sr and Eu troughs from plagioclase, and Ti or P troughs from oxides or apatite.

Data you need

• Up to 28 elements in ppm, by default in the order Rb, Cs, Ba, Th, U, Nb, Ta, K, La, Ce, Pb, Pr, Sr, Nd, Zr, Hf, Sm, Eu, Ti, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, Lu.
• K and Ti must be supplied as ppm columns named K and Ti; Kaligeos does not convert them from K₂O or TiO₂.

Plotting a spider diagram in Kaligeos

• Normalization to primitive mantle of Sun & McDonough (1989); the Y axis reads “Sample / Primitive mantle”.
• “Configure elements…” reorders elements, hides the ones you do not need and restores the default order.
• Markers, lines, logarithmic minor ticks, automatic or manual Y range and the option to connect across missing elements.
• Import CSV or Excel (.xlsx, .xlsm) tables. Kaligeos recognizes common oxide and element headers regardless of case, accents or punctuation, for example FeOt, FeO*, “La ppm” or “La (ppm)”.
• Values below detection such as “<0.5” are imported as half the limit by default; you can choose L/√2, a custom fraction or leave them empty.
• Group samples with reusable legend schemes, keep several diagrams linked to the same selection and save views inside a .kaligeos project.
• Export the figure as SVG or PDF for papers, theses and posters. Kaligeos Community includes 50 vector exports per account.

Frequently asked questions

Can I normalize to N-MORB or chondrite instead of primitive mantle?

Not in the spider diagram at present: it uses primitive mantle of Sun & McDonough (1989). Chondrite normalization is available in the REE diagram and in normalized ratios.

My table has K₂O and TiO₂ but no K or Ti in ppm. What should I do?

Add K and Ti columns in ppm to your table before importing (K ppm = K₂O wt% × 8301.5; Ti ppm = TiO₂ wt% × 5995).

References

• Sun, S.-s. & McDonough, W. F. (1989). Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications 42, 313–345.

Related diagrams

• REE diagramChondrite-normalized rare earth element patterns (Sun & McDonough, 1989).
• Pearce diagramsTh/Yb–Nb/Yb, granite discrimination and other tectonic discrimination diagrams.
• Generic XY plotScatter plots of any variable, sum or element ratio, including normalized ratios.