VII. Economic Resources
(also see Socioeconomic Uses section)
A. Petroleum
The sedimentary basins both onshore and offshore, including the Outer
Santa Cruz basin, were formed along the California margin during the transition
period between subduction and transformation. These basins were then enlarged,
elongated, filled and deformed during the transform movement, and transported
on the Pacific plate to their present location. During their evolution many
of these basins underwent a depositional and thermal history that favored
the generation and concentration of hydrocarbons. Today, onshore seeps of
tar sands are present along the coast between Santa Cruz and Davenport (Phillips
1990). Offshore, a concentration of shallow hydrocarbons, including natural
seepage of thermogenic hydrocarbons into the oceanic water column, occurs
near the southern terminus of the outer Santa Cruz basin (Nagel 1983, Nagel et al. 1986). Several oil fields have been developed in the region,
including the Half Moon Bay, La Honda and Moody Gulch fields (Wright 1990).
All are located along structures that resulted from Neogene and Quaternary
tectonic movement (McCulloch 1987).
B. Minerals
With the exception of jade, no economically important deposits of minerals
have been located within the MBNMS. Phosphate coating has been identified
on rocks in Monterey Canyon (Greene 1977, Galliher 1932), but are not of
the concentration to warrant mining.
Jade and jadeite exist along the Big Sur coast, and have been mined for
years. They are eroded from Franciscan rocks during periods of severe storms
and heavy winter rains. An especially large block (9000 lbs) of nephrite
jade was taken from the nearshore seafloor in 1971 (Wobber 1975). Amateur
mineralogists and gem collectors regularly comb the Big Sur coast for jade,
and much jade is still believed to occur offshore.
C. Building materials
Though sand and gravel are mined from the Santa Margarita Formation
in the Santa Cruz Mountains (Phillips 1981) and limestone and dolomites
are mined from the Santa Cruz, Gabilan, and Santa Lucia Mountains, these
materials have not been mined along the coast or within the MBNMS. However,
mining of fine-grained quartzose sands used in porcelain making has taken
place in the nearshore regions of southern Monterey Bay (Arnal et al. 1973,
Galliher 1932). Only one sand mine operation exists (in Marina).Historically,
as many as three or four sand mining operations exported these sands all
over the world.
Next - Section VIII.
Selected Geology Resources
Geology Table of Contents