Publikationsdatum:
2024-05-15
Beschreibung:
Transmission electron microscopy observations and rock magnetic measurements reveal that alteration of fine- and large-grained iron-titanium oxides can occur at different rates. Fine-grained titanomagnetite occurs as a crystallization product within interstitial glass that originated as an immiscible liquid within a fully differentiated melt; in several samples with ages to 32 Ma it displays very little or no oxidation (z = ca. 0). In contrast, samples with ages of 10 Ma or older are observed to also contain highly oxidized (z 〉/= 0.66) large-grained titanomaghemite. These large grains, having originated by direct crystallization from melt, are associated with pore space. Such pore space can serve as a conduit for fluids that promote alteration, whereas fine grains may have been "armored" against alteration by the glass matrix in which they are embedded. Apparently, alteration of oceanic crust is a heterogeneous process on a microscopic scale. The existence of pristine, fine-grained titanomagnetite in the interstitial glass of older ocean-floor basalts that have undergone significant alteration implies that such glassy material is capable of carrying original thermal remanent magnetization and may be suitable for paleointensity determinations.
Schlagwort(e):
34-320B; 37-335; 73-519A; 82-556; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Leg34; Leg37; Leg73; Leg82; North Atlantic; North Atlantic/RIDGE; South Atlantic/RIDGE; South Pacific/BASIN
Materialart:
Dataset
Format:
application/zip, 2 datasets
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