Yes, interact or exchange with meteoric water at high-T could lead to marine carbonate with negative delta18O values as pointed out by David. If this occur, however, delta13C may remain its original values unchanged.

I agree Decreases in d18O values during diagenesis can be related to the influence of 18O-depleted meteoric waters as well as to elevated temperatures during post-depositional alteration.

What was the original carbonate mineralogy, LMC or HMC/Aragonite (during the Jurassic it could've been either)?

What is the current mineralogy? If it's different, then your rocks have undergone neomorphism (near certainty that they did) and your d18O values reflect the temperature and water d18O during neomorphism.

Then ask yourself the following questions:

1.) What was the temperature of neomorphism/formation?

2.) What were the potential fluid sources?

3.) Was there a meteoric fluid source?

4.) What were possible d18O values of your fluids?

Then with that data, plug it into calcite-water fractionation equation e.g. Friedman and O'Neil (1977) and see if you get realistic values.

Examples:

Seawater with a d18O of 0 per mil VSMOW at 25 oC produces a calcite with -2.45 per mil VPDB.

Seawater with a d18O of -2 per mil VSMOW at 25 oC produces a calcite with -4.39 per mil VPDB. (The upper end of your values)

Seawater with a d18O of -2 per mil VSMOW at 45 oC produces a calcite with -8.08 per mil VPDB. (The lower end of your values)

Now it's up to you to figure out if those are realistic temperatures or fluid d18O based on other data. I agree with Xue-Ming Yang that even if meteoric waters interacted with your rocks, the d13C may still reflect the original carbonate values.

To see an example of how to do this you can check out my publication:

Article Early diagenesis driven by widespread meteoric infiltration ...

And the calcite-water fractionation equation is below:

Chapter Compilation of stable isotope fractionation factors of geoch...

Good luck!