Coastal submarine hydrothermal activity off northern Baja California: 2. Evolutionary history and isotope geochemistry

Abstract

A geochemical model of the Punta Banda submarine hydrothermal system (PBSHS) and Ensenada quadrangle subaerial hot springs is developed using 18O/16O, D/H, 34S/32S, 3H, water and gas chemistry. The PBSHS water is a primary high temperature, acid, reducing fluid of old seawater origin which has been titrated by cold, alkaline groundwater of meteoric origin. The final exiting solutions represent a 1 : 1 mixture of the two primary mixing components. In contrast, the subaerial hot spring waters are of unmixed meteoric origin. The subaerial hot spring gas is predominantly atmospheric N2, while the PBSHS contains large amounts of CH4 and N2 derived from trapped marine sediments of Cretaceous age; δS34 values of sampled hydrothermal waters are similar to Cretaceous marine sulfate values and suggest that the waters contacted Cretaceous marine sedimentary strata. The presence of the Alisitos and Rosario marine sedimentary formations of Cretaceous age within the Ensenada‐Punta Banda quadrangle renders support to the above hypothesis. The data also demonstrate that pyrite mineralization and deposition in submarine hydrothermal environments result from the complexing of ferrous iron with elemental sulfur and sulfide and that submarine hydrothermal activity acts as a major source of silica, Ca2+, and trace metals and as a major sink for seawater Mg2+ and SO42−.

Insights into hydrological regime of Lake Vostok from differential behavior of deuterium and oxygen‐18 in accreted ice

“…But these slopes correspond to the line between hydrothermal and local meteoric waters feeding the hydrothermal circulation (S w-HT ). The ddD/dd 18 O slope in the hydrothermal waters (S HT ) may thus be quite different [Polya et al, 2000;Vidal et al, 1981;Vuataz and Goff, 1986;Xu et al, 2006], depending on various factors, among which the most important are the water and rock geochemistry, the groundwater recharge by meteoric waters, the renewal time of underground water pools, the fractionation during separation of vapor fraction. The isotopic alteration of hydrothermal waters has different mechanisms for dD and d…”

Mantle Degassing Through Continental Crust Triggered by Active Faults: The Case of the Baja California Peninsula, Mexico

“…The distinction between colored and gray symbols is as in Figure caption. The reported literature data are as follows: SSGF from Mazzini et al (); CPGF from Welhan et al (), Polyak et al (), Birkle et al (), and Pinti et al (); LTVGF from Birkle et al (); LV from Schmitt et al (); PB, SC, and UR from Vidal et al (); UR, AC, SC, SV, VG, SA, and ECH from Polyak et al (); and BC from Forrest et al (). (b) Binary plot of the CH 4 /CO 2 ratio versus 3 He/ 4 He corrected for air contamination (Rc/Ra).…”

“…This degassing extends north to the Cerro Prieto and Salton Sea geothermal fields and to the western coast of the peninsula. In the latter, the emission of gases is not related to the rifting process but to the presence of local faults (Polyak et al, ; Vidal et al, ).…”

Geothermal prospects in the Baja California Peninsula

“…Geochemical data on the Ensenada's region surface manifestations waters have been reported by Vidal et al (1978Vidal et al ( , 1981, Álvarez-Rosales (1993) and Arango-Galván et al (2011). Silica geothermometric temperatures (Fournier et al, 1982) on the hot springs vary from 120 to 140 • C, while the calculated value for the submarine vents is 126 • C (Arango-Galván et al, 2011).…”