Characterization of diagenetic fluids at ODP Site 103-639

Site 639, drilled during Leg 103 of the Ocean Drilling Program, penetrated an Upper Jurassic to Lower Cretaceous carbonate platform on a tilted fault block along the Galicia margin off the northwest Iberian Peninsula. The carbonate platform is composed primarily of a sequence of dolomite overlying l...

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Bibliographic Details
Main Authors: Haggerty, Janet A, Smith, Michael P
Format: Dataset
Language:English
Published: PANGAEA 1988
Subjects:
103-639A
103-639B
103-639C
103-639D
DRILL
Drilling/drill rig
Joides Resolution
Leg103
North Atlantic Ocean
Ocean Drilling Program
ODP
Newfoundland
North Atlantic
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.743488
https://doi.org/10.1594/PANGAEA.743488
Description
Summary:Site 639, drilled during Leg 103 of the Ocean Drilling Program, penetrated an Upper Jurassic to Lower Cretaceous carbonate platform on a tilted fault block along the Galicia margin off the northwest Iberian Peninsula. The carbonate platform is composed primarily of a sequence of dolomite overlying limestone. Samples were analyzed for mineral chemistry, stable isotope geochemistry, fluid inclusion microthermometry, and volatile contents and by dolomite pyrolysis mass spectrometry for trace sulfate minerals. The dolomite recovered from the Galicia margin at Site 639 formed during shallow burial from sulfate-bearing, hypersaline brines at slightly elevated temperatures. The light oxygen isotopic signatures of the dolomite are interpreted as the result of the evaporative loop and slightly elevated temperatures during dolomite formation or from reequilibration at higher temperatures during deeper burial. The hypersalinity is interpreted to be associated with a nearby, shallow restricted basin that formed during rifting of the Iberian margin from Newfoundland. The dolomitization of the platform is therefore a by-product of the rifting.

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