GSA (Geological Society of America) doesn't have a complete style guide, but they Reference Guidelines and Examples for authors on their website regarding formatting for manuscript templates.
NOTE:
Chinese names are commonly arranged family name first, followed by a given name (see Book example below); for references with Chinese authors, spell out the entire name.
Include the names of co-chief scientists for publications.
In text citation examples
One author: (Name, Year, p. xxx) --> (Taylor, 1990, p. 154)
NOTE: Page numbers required only if a direct quote is used.
Two authors: (Author 1 and Author 2, Year, p. xxx) --> (Kane and Neuzil, 1993)
Three or more authors: (Author 1 et. al., year) --> (Sawyer et al., 1991)
Or to cite works in one sentance: (Taylor, 1990, p. 154; Sawyer et al., 1991; Kane and Neuzil, 1993)
Reference list examples
Author, O., and Author, P., Year, Title of article: Title of Publication, v. xx, p. xxx-xxx.
Brown, M., 1993 P-T-t evolution of orogenic belts and the causes of regional metamorphism: Journal of the Geological
Society [London], v. 150, p. 227-247.
Last Name, X., Last Name, Y. and Last Name, A., Year, Title of article: Title of Publication: City of Publication, State,
Series, xx p.
Burchfiel, B.C., Chen Zhiliang, Hodges, K.V., Liu Yuping, Royden, L.H., Deng Changrong and Xue Jiene, 1992, The
South Tibetan detachment system, Himalayan orogen: Extension contemporaneous with and parallel to shortening in a collisional mountain belt: Boulder, Colorado, Geological Society of America Special Paper 269, 41 p.
Last Name, A., Year, Name of presentation: Conference Title, City, State, Abstracts, v.x, p. xxx.
Fitzgerald, P.G., 1989, Uplift and formation of Transantarctic Mountains: Applications of apatite fission track analysis to
tectonic problems: International Geological Congress, 28th, Washington, D.C., Abstracts, v.1, p.491.
Last Name, A. B., Year, Title of page or site, url (Date accessed).
or
TITLE OF BLOG, Year, Title of post, url (Date accessed).
Johnson, A.B., 2001, Raw data for relay stations AB1-AB15 in the Mojave desert:
http://www.seismo.berkeley.edu/mojave (December 2001)
MARGINS, 1999, The Seismogenic Zone Experiment (SEIZE): Science plan:
http://www.soest.hawaii.edu/margins/SEIZE_sci_plan.html (July 2001)