Expedition 385 methods

Abstract

The best precaution is to ensure that the operating temperature is constant during measurements, and preferably cool, and that sensor and samples have time to reach an equilibrium temperature. This may be more difficult when operating in the field. Wet ConditionsCaution: These instruments are protected against the ingress of moisture but operation in very wet conditions should be avoided.Note: Some sensors can be operated while submerged in water: see product brochure for further information. Noise and Interference CheckCaution: These instruments should not be operated close to high power radio transmitters, heavy electrical machinery, computers, or other electrical or magnetic equipment. Note:The unit is unlikely to be affected by interference from other equipment in the normal operating environment. However, by their nature the sensors are susceptible to electromagnetic interference and operation close to a radio frequency source with a frequency close to the operating frequency of the sensor should be avoided. It is important to position the sensor to minimise interference and obtain the best performance.Select the normal sensitivity, x1.0 range. With no sample present, first press the 'Z' button and then select continuous measurements on the 'M' toggle switch. If fluctuations of greater than ±1 least significant digit per reading appear on the display then external electrical noise should be suspected. In this case the only solution is to re-site the equipment.Before using the laboratory sensors, first check the selected area for freedom from large ferrous objects by moving the sensor and watching for any changes on the display.

Site U1545

“…Lithostratigraphic description and analysis were carried out based on the curated length of the cores (on the CSF-A depth scale), but all references to CSF-A depths in text, figures, and tables are given as meters below seafloor, unless otherwise noted. Lithologic description and interpretation are based on a combination of macroscopic core description, smear slide and thin section examination with a petrographic microscope, MS and NGR measurements, color reflectance analysis, and mineralogic analysis using X-ray diffraction (XRD) and carbonate analyses (see Lithostratigraphy and Petrophysics in the Expedition 385 methods chapter [Teske et al, 2021a]; see also Inorganic geochemistry and Organic geochemistry). Most of the observations and the depths used in this section refer to Hole U1545A because it was the deepest hole drilled.…”

“…It is defined as a "gap zone" bounded by the bottom of E. huxleyi (0.29 Ma) as the upper boundary and the top of P. lacunosa (0.44 Ma) as the lower boundary. The absence of P. lacunosa and other zonal markers (see Figure F20 in the Expedition 385 methods chapter [Teske et al, 2021a]) in Samples 385-U1545A-41F-CC to 74X-CC and 385-U1545B-42F-1, 50 cm, to 67X-CC, 28 cm, indicates that this interval falls above the top of P. lacunosa (0.44 Ma), suggesting a middle Pleistocene age (0.29-0.44 Ma) with the bottom of both holes younger than 0.44 Ma.…”

“…Paleomagnetic measurements on archive-half sections from Hole U1545B were carried out on Cores 46F-60F (with the exception of Core 48X) to increase the depth interval for paleomagnetic measurements for HLAPC cores. Paleomagnetic measurements for Cores 1H-45F were not conducted because of (1) a discontinuous record of the archive-half sections due to complete sampling of whole-round sections (approximately a few meters per core) for microbiology and geochemistry (see Microbiology, Inorganic geochemistry, and Organic geochemistry in the Expedition 385 methods chapter [Teske et al, 2021a]) and ( 2) the absence of excursions and reversals in the paleomagnetic record (see Magnetostratigraphy).…”

“…Measurements of remanence were made using an AGICO JR-6A dual speed spinner magnetometer on a total of sixty 8 cm 3 cube samples (see Figure F21 in the Expedition 385 methods chapter [Teske et al, 2021a]). All of these samples were demagnetized using a stepwise increasing AF to isolate the ChRM direction by means of principal component analysis (PCA) (Kirschvink, 1980).…”

Microbial Hydrocarbon Degradation in Guaymas Basin—Exploring the Roles and Potential Interactions of Fungi and Sulfate-Reducing Bacteria

“…Analysis of the mRNA pool, proteome, and secretome isolated from samples along the depths drilled at each site are necessary to inform on the active fraction of the community and on microbial strategies for coping with increasing heat and the stresses of ever-scarcer nutrients with depth. The application of recently developed molecular methods such as bioorthogonal non-canonical amino acid tagging (BONCAT), RNA-SIP, and live/dead stains applied to isolated cells are needed to confirm results from interpretations of molecular data as to the fraction of the in situ community that is actively contributing to nutrient cycling in the deep subsurface Guaymas biosphere ( Teske et al, 2021c ). In the anoxic deep biosphere, we may discover diverse fungal-bacterial syntrophic interactions, that allow the syntrophic partners to survive by adapting to different sources of carbon and/or energy, and by cooperating in accessing substrates that individual taxa cannot access alone.…”