Downwelling solar irradiance, upwelling solar radiance, sky leaving radiance, and cloud cover observed during ARCHEMHAB study (on Maria S. Merian Leg MSM21/3) from 2012-07-26 to 2012-08-10

The need to obtain ocean color essential climate variables (OC-ECVs) using hyperspectral technology has gained increased interest in recent years. Assessing ocean color on a large scale in high latitude environments using satellite remote sensing is constrained by polar environmental conditions. Nevertheless, on a small scale we can assess ocean color using above-water and in-water remote sensing. Unfortunately, above-water remote sensing can only determine apparent optical properties leaving the sea surface and is susceptible to near surface environmental conditions for example sky and sunglint. Consequently, we have to rely on accurate in-water remote sensing as it can provide both synoptic inherent and apparent optical properties of seawater. We use normalized water leaving radiance LWN or the equivalent remote sensing reflectance RRS from 27 stations to compare the differences in above-water and in-water OC-ECVs. Analysis of above-water and in-water RRS spectra provided very good match-ups (R2 > 0.97, MSE<1.8*10**-7) for all stations. The unbiased percent differences (UPD) between above-water and in-water approaches were determined at common OC-ECVs spectral bands (410, 440, 490, 510 and 555) nm and the classic band ratio (490/555) nm. The spectral average UPD ranged (5 - 110) % and band ratio UPD ranged (0 - 12) %, the latter showing that the 5% uncertainty threshold for ocean color radiometric products is attainable. UPD analysis of these stations West of Greenland, Labrador Sea, Denmark Strait and West of Iceland also suggests that the differences observed are likely a result of environmental and instrumental perturbations.

(Table 1) Uncompacted and compacted sedimentation rate values corrected for bedding attitudes at DSDP Leg 66 Holes

Sediment accumulation rates, computed using agesediment thickness curves obtained from DSDP cores, are rarely corrected for compaction or bedding attitude to better approximate true sediment accumulation rates (c.f. van Andel et al., 1975; Davies et al., 1977; and Whitman and Davies, 1979). Variations with depth in either of these factors can hinder interpreting relative rates of sedimentary processes associated with a particular depositional environment. This problem becomes particularly relevant for convergent margin sediments, which often display variable bedding attitudes and pronounced changes in porosity, bulk density, and other parameters related to the compaction process at shallow depth. These rapid shallow changes render correlation of sedimentation rates within a single transect of holes very difficult. Two techniques have been applied to data collected from a transect of holes along the southwestern Mexico continental margin, DSDP Leg 66 (Fig. 1), to correct sediment accumulation rates for variations in compaction and bedding attitude. These corrections should help resolve true fluctuations in accumulation rates and their implications regarding convergent margin processes.

Geochemistry and pyrolysis at DSDP Hole 77-535

There are substantial differences in the character of organic matter contained in the Pleistocene and Cretaceous sedimentary sequences of DSDP Site 535. The argillaceous Pleistocene section contains type III, gas-prone organic matter whereas the calcareous Cretaceous section is dominated by type II, oil-prone organic matter. A more detailed investigation of the Cretaceous section reveals that the finely laminated limestones of Valanginian to Barremian age are of good to excellent source quality. The indigenous organic matter contained within this organically rich section is thermally immature, not having undergone sufficient thermal diagenesis for the generation and expulsion of hydrocarbons. Within this stratigraphic section, however, staining by mature hydrocarbons was detected. These stains are associated with a fractured interval. These fractures may in turn represent potential migration pathways.

40Ar-39Ar geochronological studies on rocks at DSDP Leg 58 Holes

The technique of 40Ar-39Ar step-heating dating was applied to three rock samples from core of DSDP Site 443, one sample from Site 445, and four samples at Site 446. All sites were drilled during DSDP Leg 58. At Site 443 (Shikoku Basin), about 116 meters of basalt basement was drilled. Three samples were chosen for dating from different levels in the basalt; two samples are aphyric basalt, and the other is subophitic dolerite. At Site 445 (Daito Ridge), no basement rock was drilled; however, conglomeratic sandstone was cored in the lower part of the hole. 40Ar-39Ar dating was applied to a basalt pebble in the conglomerate. At Site 446 (Daito Basin), the lower cored sequence is clay stone interlayered with 16 basalt sills. Four samples were chosen from sills at different levels.