Measuring device and method for carbon and oxygen isotopes of carbonate rocks

Abstract

The invention discloses a measuring device and method for carbon and oxygen isotopes of carbonate rocks. The device comprises an ultraviolet laser ablation device and a carbon and oxygen isotope measurer. The ultraviolet laser ablation device comprises an ultraviolet laser and a carbonate sample cell. The ultraviolet laser is arranged above the carbonate sample cell. The carbonate sample cell is provided with a helium inlet and a helium outlet. A helium outlet pipe is provided with a spherical grinding connector, and a quartz filtering film is arranged in the middle of the spherical grinding connector. The oxygen isotope measurer comprises an automatic sample injector, a water removing trap A, an eight-way valve, a chromatographic column, a water removing trap B, an opening shunt and a mass spectrometer, all of which are connected in sequence. The method comprises the steps that a carbonate sample ablated through the ultraviolet laser device is conveyed to the carbon and oxygen isotope measurer, and the carbon and oxygen isotopes are measured through the phosphoric acid hydrolysis method. The problem that in an infrared laser probe carbonate microcell normal-position carbon and oxygen isotope analyzing method, the isotope fractionation cannot be accurately corrected is solved, and the precision and accuracy of an analysis result are greatly improved.

Description

technical field

[0001] The invention relates to the field of isotope analysis of rock minerals, in particular to a measuring device and method for carbon and oxygen isotopes of carbonate rocks. Background technique

[0002] Carbon and oxygen stable isotopes (δ 13 C and delta 18 O) analysis is an important part of the study of carbonate rock geochemistry. The routine analysis of carbonate carbon and oxygen isotopes is the phosphoric acid method proposed by McCree (1950), which has the advantages of stable data and simple operation. Rock samples react with phosphoric acid to generate CO 2 (CaCO 3 +H 3 PO 4 → Ca 3 (PO 4 ) 2 +H 2 O+CO 2 ), sent to a gas mass spectrometer to analyze and determine its carbon and oxygen isotopes. The main disadvantages of this method are: due to the limitation of manual and drilling tool sampling, not only cumbersome rock ore separation is required, but also the required sample volume is large (>10mg), and the spatial resolution is l...

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