--> ABSTRACT: Origin of Production Gases from Convergent Plate Margins, by Alan W. A. Jeffrey, Robert J. Poreda, William J. Gwilliam, Ian R. Kaplan, and Harmon Craig; #91038 (2010)
[First Hit]

Datapages, Inc.Print this page

Origin of Production Gases from Convergent Plate Margins

Previous HitAlanTop W. A. Jeffrey, Robert J. Poreda, William J. Gwilliam, Ian R. Kaplan, Harmon Craig

Molecular and isotopic compositions of hydrocarbon production gases from four convergent plate margins have been measured. New Zealand is represented by two gases from the Taranaki basin in the back arc of the active Tonga-Kermadec subduction system. Gases from Barbados and Taiwan are from forearc locations in the active Lesser Antilles system and relict northern Manila Trench system. Philippine gases from offshore Palawan are associated with the Palawan Trough. Gases from Taiwan, the Maui field in New Zealand, and the Nido field in Palawan have very high 3He/4He ratios, indicating considerable mantle input of helium to the gas reservoirs. Variations in 3He/4He ratios in neighboring fields are quite striking and suggest localize sources for the mantle components. Possible sources include shallow igneous bodies and fractures or faults tapping a direct mantle source.

Measurements of helium isotope ratios in hydrocarbon production gases have been compiled and show a striking association of mantle helium with gases from subduction zones in contrast to deep subsided or rifted sedimentary basins. The dynamics of the subduction process, involving the interaction of upper mantle and crustal rocks, is apparently responsible for the injection of volatile mantle components into reservoired gases. Current exploration techniques are based on maturation and gas migration theories developed from the study of subsiding sedimentary basins. At convergent margins, such techniques may have to be amended to include the effects of subduction dynamics on the source, maturation, and migration of hydrocarbons.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.