Laser-induced　breakdown　spectroscopy　(LIBS)　has　provided　an　optional　access　method　to　analyze　multiple　components　of　geomaterials　with　the　advantages　of　rapid　detection　and　minimal　damage　and　preprocessing　of　samples　compared　with　other　conventional　analytical　methods.　A　fiber-optic　LIBS　(FO-LIBS)　system　with　a　compact　laser　probe　was　established　to　analyze　ten　different　sediment　samples,　with　Al,　Fe,　Ca,　Mg,　Ti,　Mn,　V,　and　Cr　successfully　detected.　The　spectra　from　the　different　samples　are　quite　different　due　to　matrix　effects,　and　the　spot　size　has　a　great　influence　on　both　plasma　evolution　and　emission　spectra　for　the　same　sample.　The　laser　irradiance　decreased　from　1.382　to　0.855　GW/cm2　with　increasing　the　spot　diameter　from　480　to　610　μm　as　the　spectral　fluctuation　was　gradually　aggravated.　Internal　standardization　(IS)　was　utilized　to　decline　the　spectral　fluctuations　caused　by　the　spot　size　and　matrix　effects　for　the　quantification　of　multiple　elements.　By　adopting　the　most　suitable　combinations　of　emission　lines,　the　fluctuation　of　emission　lines　caused　by　the　spot　size　was　also　limited　with　a　relative　standard　deviation　lower　than　30%.　The　R2　of　all　the　calibration　curves　was　higher　than　0.9　with　the　major　element　Si　out　of　the　detection　range　and　spectra　mixed　at　different　spot　sizes,　which　outperformed　normalization　by　the　whole　spectrum.　Two　multi-variate　chemometric　methods,　including　partial　least　squares　regression　and　support　vector　regression,　were　also　applied　to　establish　quantitative　models　for　the　sediments.　It　was　found　that　three　methods　provided　similar　prediction　results,　while　IS　could　establish　a　more　robust　calibration　model　that　was　less　sensitive　to　spot　size.　This　study　also　demonstrated　that　FO-LIBS　has　the　potential　to　quantitatively　analyze　the　chemical　compositions　of　geomaterials　combined　with　IS　and　machine　learning.　©　2022　Elsevier　B.V.