Nd isotope composition of seep carbonates: Towards a new approach for constraining subseafloor fluid circulation at hydrocarbon seeps

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27350%2F19%3A10239629" target="_blank" >RIV/61989100:27350/19:10239629 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0009254118305187" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0009254118305187</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemgeo.2018.10.015" target="_blank" >10.1016/j.chemgeo.2018.10.015</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Nd isotope composition of seep carbonates: Towards a new approach for constraining subseafloor fluid circulation at hydrocarbon seeps

Popis výsledku v původním jazyce

The carbonates forming at deep-sea hydrocarbon seeps provide an archive for the source and migration pathways of the seeping fluids. Interpretation of the archived isotopic and elemental signatures is, however, not straightforward because of mixing between the signals of fluids and ambient seawater, limited understanding of subseafloor fluid circulation, and effects of diagenetic alteration. The Nd isotope system is among the most widely used tracers of circulation patterns in modern and past oceans, but to date Nd isotopes have been rarely used in investigations of fluid migration pathways at hydrocarbon seeps. To test the sensitivity of Nd isotope signals of seep carbonates to record past interactions between the seeping fluids and Nd-143-enriched, volcanic-derived mineral components, we performed Nd, Sr and stable isotope analyses of the Lower Cretaceous (Barremian) seep carbonates found in Bagka (Czech Carpathians). These seep deposits are directly underlain by a complex of mafic igneous rocks, which the methane-charged fluids must have passed through on their way to the seafloor. The epsilon(Nd)(t) values measured in the seep carbonates are significantly more radiogenic than the inferred signal of contemporaneous local seawater, and shifted towards the composition typical of the underlying basaltoids. This is in agreement with the Sr-87/Sr-86 ratios, which are markedly lower that the coeval seawater signature. Consistent co-variance trends are observed among the measured epsilon(Nd)(t), Sr-87/Sr-86 and delta C-13 values, attesting increasing role of the volcanic-derived fluid component with increasing contribution of methane-derived carbon. The results of the present approach reveal the potential of Nd isotopes to fingerprint exotic fluid end-members present in plumbing systems of both fossil and modern methane discharges. The method can be of particular use in studies of seeps associated with plate margins, where Nd-143-enriched igneous materials are commonly encountered in the basement or in the sediment column.

Název v anglickém jazyce

Nd isotope composition of seep carbonates: Towards a new approach for constraining subseafloor fluid circulation at hydrocarbon seeps

Popis výsledku anglicky

The carbonates forming at deep-sea hydrocarbon seeps provide an archive for the source and migration pathways of the seeping fluids. Interpretation of the archived isotopic and elemental signatures is, however, not straightforward because of mixing between the signals of fluids and ambient seawater, limited understanding of subseafloor fluid circulation, and effects of diagenetic alteration. The Nd isotope system is among the most widely used tracers of circulation patterns in modern and past oceans, but to date Nd isotopes have been rarely used in investigations of fluid migration pathways at hydrocarbon seeps. To test the sensitivity of Nd isotope signals of seep carbonates to record past interactions between the seeping fluids and Nd-143-enriched, volcanic-derived mineral components, we performed Nd, Sr and stable isotope analyses of the Lower Cretaceous (Barremian) seep carbonates found in Bagka (Czech Carpathians). These seep deposits are directly underlain by a complex of mafic igneous rocks, which the methane-charged fluids must have passed through on their way to the seafloor. The epsilon(Nd)(t) values measured in the seep carbonates are significantly more radiogenic than the inferred signal of contemporaneous local seawater, and shifted towards the composition typical of the underlying basaltoids. This is in agreement with the Sr-87/Sr-86 ratios, which are markedly lower that the coeval seawater signature. Consistent co-variance trends are observed among the measured epsilon(Nd)(t), Sr-87/Sr-86 and delta C-13 values, attesting increasing role of the volcanic-derived fluid component with increasing contribution of methane-derived carbon. The results of the present approach reveal the potential of Nd isotopes to fingerprint exotic fluid end-members present in plumbing systems of both fossil and modern methane discharges. The method can be of particular use in studies of seeps associated with plate margins, where Nd-143-enriched igneous materials are commonly encountered in the basement or in the sediment column.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10502 - Oceanography

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Chemical Geology

ISSN

0009-2541

e-ISSN

—

Svazek periodika

503

Číslo periodika v rámci svazku

JAN 5 2019

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

40-51

Kód UT WoS článku

000451060800004

EID výsledku v databázi Scopus

—