Page 641 - Economia Azul - versão: inglês

The main contribution of organic mat- surface, a factor that influences the orig-
chimneys with different hydrate satura- in yellow below the BSR suggest the exis-
tions. The inversion of the CSEM data re- tence of a zone of higher concentration ter in the formation of GH was marine or- inal organic matter and, therefore, masks
veals that the largest resistivity anomalies of free gas. The acoustic data (amplitude ganic carbon based on the results of the the ages of the organic matter.
13
within the gas hydrate stability zone are anomalies below the BSR) encompass this stable isotope of carbon (δ C-org) and Gas hydrate accumulations near the
possibly associated with gas hydrate sat- anomalous CSEM zone. total organic carbon/total nitrogen ratios seafloor in RGC pockmarks appear to
urations. Note that the CSEM anomalies Source: Authors elaboration, 2022 (RODRIGUES et al., 2019). Rodrigues et. be associated with pockets of gas from
al, (2019) observed a contribution of fluids shallow depths (tens of meters below
The gas in the hydrate is primarily meth- origin of the gases was classified as bio- from deep sediments, which transported the seafloor – Rodrigues et al., 2017)
ane with traces of ethane, and the stable genic. Likewise, studies of free gases in “old” organic compounds (> 50 ka) to the which, in turn, support chemosynthetic
carbon isotopes of the methane indicate sediments were produced by microbial

13
a microbial origin (δ C values from -69.3 methanogenesis, that is, gaseous hydrocar- Figure Z7
to -66.7; Miller et al., 2015; Rodrigues et bons were generated mainly through the
al., 2019). According to the diagrams, the microbial reduction of CO2 (Figure Z6). Images obtained
in the area
of PC22 in
which tubular
Figure Z6: Relationship between the values of δ C H polychaetes

13
6
2
and δ CH for samples from different areas of the of the genus
13
4
Rio Grande Cone (CONEGAS Project, 2021) Escarpia
occur, the
most frequent
-70 1 1
Microbi�I CH andjC : members of the
, . ----- 4 , 2 . , Area A chemosynthetic
: ,.· · · · ·· : 1 1 ••••••• � ••••• 1
: : I.' · • ···-,, \ �1•• ····�······ 1 1 : community.
■ ■ ■ ■ ■ ■ ■ ■ ■
1
1
f
\
-60 __________________ '\·.. ----;�------ � ------ 1 ---------- � ----------------- � -----------------r-----------------
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1
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.• The images
1 1 1
:
1 were taken
.
{O
I ---.. ___ \ '. : J ·· • ······ . ..... �...... . Area S 1 1 Área with a remotely
1
■ ■ I t ■ ■ ■ ■ ■ ■
1
N -50 ------------- --�:------------�---r------ 1 ----------r-----------------r-----------------T----------------- •ROV operated vehicle
!
;
1
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/
...
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() 1 ', - ,' J 1 1 1 . PC109 A (ROV) and an
- - - - - - - - - - - - - - - - - - -•- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - PC105 A autonomous
:
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-40 -----------------�-----------------r------ 1 ----------�-----------------r-----------------T-----------------· •PC92 underwater
1
1
i
1
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1 1 1 1 1 1 1 E
1 1 vehicle (AUV),
1 �PC95 E
Thermogenic CH anjd C 2 both used in
4
1
-30 ----------------- -----------------·-------�---------�-----------------�----------------- 1----------------- the CONEGAS
1
1
1
1
1 1 1 1 1 1
Microbjial CH an� project scientific
4
Thernjlogenic C ; cruises.
2
-20 1 1
-80 -70 -60 -50 -40 -30 -20
o 13 C of CH 4
Source: Authors elaboration, 2022 Source: Medina-Silva
(2018)
638 BLUE ECONOMY State of the Art of Gas Hydrate Occurrences 639