Publication Date:
2023-07-07
Description:
Heavy and light minerals were examined in 29 samples from Sites 494, 498, 499, 500, and 495 on the Deep Sea Drilling Project Leg 67 Middle America Trench transect; these sites represent lower slope, trench, and oceanic crust environments off Guatemala. All samples are Quaternary except those from Hole 494A (Pliocene) and Hole 498A (Miocene). Heavy-mineral assemblages of the Quaternary sediments are characterized by an immature pyroxene-amphibole suite with small quantities of olivine and epidote. The Miocene sediments yielded an assemblage dominated by epidote and pyroxene but lacking olivine; the absence of olivine is attributed to selective removal of the most unstable components by intrastratal solution. Light-mineral assemblages of all samples are predominantly characterized by volcanic glass and plagioclase feldspar. The feldspar compositions are compatible with andesitic source rocks and frequently exhibit oscillatory zoning. The heavy- and light-mineral associations of these sediments suggest a proximal volcanic source, most probably the Neogene highland volcanic province of Guatemala. Sand-sized components from Site 495 are mainly biogenic skeletons and volcanic glass and, in one instance (Section 495-5-3), euhedral crystals of gypsum.
Keywords:
67-494; 67-494A; 67-498A; 67-499; 67-500; Amphibole; Apatite; Clinopyroxene; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Electron microprobe (EMP); Elevation of event; Epidote; Epoch; Event label; Glomar Challenger; Heavy mineral grains; Latitude of event; Leg67; Longitude of event; North Pacific/TRENCH; Olivine; Orthopyroxene; Rutile; Sample code/label; Sphene
Type:
Dataset
Format:
text/tab-separated-values, 425 data points
Permalink