chemosynthetic bacteria metabolism produce light N isotopic signatures. These communities live around submarine vents. If not only work on sediments around vents is an older paper in Nature that give positive value of +12 per mil I think.

Could you clarify your additional explanation about TN and IN d15N values, because it seems it does not corresponds to the figures, TN (in red) showing values between 0 and -15 for site A and -10 and -20 for site B. So the opposite from your text. Also, on your histogramm, TN is in blue and IN in orange suggesting that until more than 95% of the N is from organic origin. Is it reasonable in a vent context or is it a confusion with caption again? Please clarify before we can help you :)

Could you clarify your additional explanation about TN and IN d15N values, because it seems it does not corresponds to the figures, TN (in red) showing values between 0 and -15 for site A and -10 and -20 for site B. So the opposite from your text. Also, on your histogram, TN is in blue and IN in orange suggesting that until more than 95% of the N is from organic origin. Is it reasonable in a vent context or is it a confusion with caption again? Please clarify before we can help you :)

Sorry, about that. Above figure is incorrect, it is my mistake. Revised figure attach below.

I did an analysis that nitrogen content and their nitrogen isotopic values for ammonium bearing clay fraction around vent system. And nitrogen isotope values between total nitrogen isotope value and inorganic nitrogen isotope value showed some different patterns by sampling sites (Fig. 1,2). To get the inorganic nitrogen information, I tried firstly, 6N HCl treatment and secondary, KOBr-KCl treatment after 30% H2O2 treatment.

Of course, I confirmed the existence of ammonium in crystal structure by FT-IR analysis (i.e. nearby 1450cm-1 ). And XRD analysis data showed ranging from 14-15Å (i.e. saponite, montmorillonite, nontrite; (001) interlay position).

Just I think that most of inorganic nitrogen such ammonium form can exist interlayer in 2:1 smectite in clay fractions.

About nitrogen isotope data, I think two case that one is nitrogen fractionation during mineral formation, and the other case is the possibility of some different nitrogen origin from deep mantle such reduced condition, probably.

Study area is caldera like crater in back-arc system, and overlaid sediment complex. And the  seafloor vent area be supplied volcano-clastic materials around the Bay area. So, most of smectite in this area formed from volcanic materials (previous reports). and nitrogen isotopic values of  marine sediments in this area showed ranging from 0~+5‰, respectively. and also it showed that mostof total nitrogen isotope values for clay fraction around seafloor vent system.

However, such lighter tendencies of inorganic nitrogen data for some clay samples maybe, just I think that it is possible to be affected by flux from seafloor hydrothermal vent. Actually, According to the previous data, nitrogen isotopic values of interlayer water showed lighter tendencies(-1~ -2 ‰) than pore-water’s(1~2 ‰), but I don’t know that such

However, how to demonstrate such lighter tendency of nitrogen isotope values from clay fractions(i.e. -10~20‰). If it occurred assimilation between flux and ammonium bearing minerals such reduced condition from deep mantle, how to prove those hypothesis?