Paleofluids and Recent fluids in the upper continental crust: Results from the German Continental Deep Drilling Program (KTB)

Year:

1997

Type of Publication:

Article

Authors:

Möller, P.; Weise, S. M.; Althaus, E.; Bach, W.; Behr, H. J.; Borchardt, R.; Bräuer, K.; Drescher, J.; Erzinger, J.; Faber, E.; Hansen, B. T.; Horn, E. E.; Huenges, E.; Kämpf, H.; Kessels, W.; Kirsten, T.; Landwehr, D.; Lodemann, M.; Machon, L.; Pekdeger, A.; Pielow, H. -U.; Reutel, C.; Simon, Klaus; Walther, J.; Weinlich, F. H.; Zimmer, M.

Journal:

Journal of Geophysical Research: Solid Earth

Volume:

102

Number:

B8

Pages:

18233-18254

ISSN:

2156-2202

BibTex:

@article{JGRB:JGRB10786, author = "P. M{\"o}ller and S. M. Weise and E. Althaus and W. Bach and H. J. Behr and R. Borchardt and K. Br{\"a}uer and J. Drescher and J. Erzinger and E. Faber and B. T. Hansen and E. E. Horn and E. Huenges and H. K{\"a}mpf and W. Kessels and T. Kirsten and D. Landwehr and M. Lodemann and L. Machon and A. Pekdeger and H.-U. Pielow and C. Reutel and Klaus Simon and J. Walther and F. H. Weinlich and M. Zimmer", abstract = "The two German Continental Deep Drilling Program (KTB) boreholes provided samples for studies of fluid inclusions (paleofluids), “free fluids” of the crystalline basement, and their fingerprints on the chemical and isotopic composition of minerals and rocks to 9101 m depth, which allowed reconstruction of the evolution of fluids, their migration pathways, and their sources. Aqueous fluids were largely lost during the Devonian amphibolite facies metamorphism. Thereafter, radiogenic, nucleogenic, and fissiogenic gases, together with NH4-fixed nitrogen, were released from host rocks and partly enclosed in secondary inclusions. During the Hercynian uplift, Na-Cl fluids (formation water) infiltrated and dissolved noble gases and N2 largely originating from the host rocks. In the course of the Cretaceous denudation, high-salinity Ca-Na-Cl brines, possibly derived from Permo-Carboniferous sediments but altered by fluid/rock interaction, migrated into their present position. This fluid introduced low-maturity hydrocarbons released together with nitrogen from early metamorphic organic-rich sediments. The 4000-m fluid from the KTB pilot hole pumping test, which was analyzed chemically and isotopically, seems to be a mixture of an ascending basement brine and a descending paleometeoric water, from which the late alteration minerals calcite and laumontite precipitated in fractures. The calcite is neither chemically nor isotopically in equilibrium with the recovered “free fluid.” Hydraulic tests indicate a communicating system of fractures between the boreholes with a distinct matrix and fracture porosity.", doi = "10.1029/96JB02899", issn = "2156-2202", journal = "Journal of Geophysical Research: Solid Earth", number = "B8", pages = "18233--18254", title = "{P}aleofluids and {R}ecent fluids in the upper continental crust: {R}esults from the {G}erman {C}ontinental {D}eep {D}rilling {P}rogram ({KTB})", url = "http://dx.doi.org/10.1029/96JB02899", volume = "102", year = "1997", }

Abstract:

The two German Continental Deep Drilling Program (KTB) boreholes provided samples for studies of fluid inclusions (paleofluids), “free fluids” of the crystalline basement, and their fingerprints on the chemical and isotopic composition of minerals and rocks to 9101 m depth, which allowed reconstruction of the evolution of fluids, their migration pathways, and their sources. Aqueous fluids were largely lost during the Devonian amphibolite facies metamorphism. Thereafter, radiogenic, nucleogenic, and fissiogenic gases, together with NH4-fixed nitrogen, were released from host rocks and partly enclosed in secondary inclusions. During the Hercynian uplift, Na-Cl fluids (formation water) infiltrated and dissolved noble gases and N2 largely originating from the host rocks. In the course of the Cretaceous denudation, high-salinity Ca-Na-Cl brines, possibly derived from Permo-Carboniferous sediments but altered by fluid/rock interaction, migrated into their present position. This fluid introduced low-maturity hydrocarbons released together with nitrogen from early metamorphic organic-rich sediments. The 4000-m fluid from the KTB pilot hole pumping test, which was analyzed chemically and isotopically, seems to be a mixture of an ascending basement brine and a descending paleometeoric water, from which the late alteration minerals calcite and laumontite precipitated in fractures. The calcite is neither chemically nor isotopically in equilibrium with the recovered “free fluid.” Hydraulic tests indicate a communicating system of fractures between the boreholes with a distinct matrix and fracture porosity.