Hydrated Organic Matter: Functional Relationships with the Mass Physical Static and Dynamic Properties of Marine Mud

TL;DR

This paper explores how hydrated organic matter influences the physical and dynamic properties of marine mud, highlighting the importance of accounting for organic matter in geotechnical analyses to avoid significant errors.

Contribution

It introduces a detailed analysis of hydrated organic matter's role in marine mud properties and demonstrates the potential errors in traditional measurements that neglect this component.

Findings

Hydrated OM significantly affects porosity and void ratio calculations.

Differences due to hydrated OM can reach meaningful levels even at low TOC percentages.

Accounting for hydrated OM improves the accuracy of marine mud property assessments.

Abstract

The mass physical and dynamic properties of marine mud deposits are a function of the interaction among a maximum of four sediment Phases as follows: (1) clay mineral solids that often include silt and sand size particles of different mineralogy, (2) semisolid hydrated organic matter, (3) free pore water, and (4) free gas when present. Historically, the total water was removed by oven drying which includes the seawater of hydration of the organic matter (OM); thus, the total water content was considered free pore water in several research disciplines. The semisolid hydrated OM resists transport through the mud pore space and the water that is bound to the OM is not free pore water. Calculations of marine mud mass-physical properties without consideration and correction for the presence of hydrated organic matter can introduce significant error in the amount of free water content of the pore space in the mud and the quantitative differences in both porosity and void ratio. Simulations reveal absolute relative differences due to the presence of hydrated OM that can reach meaningful values even when the %TOC values are below ~3%. Relevance is determined by comparing the differences due to the hydrated OM Phase with the differences in the fluid saturation Phase at 100% and at 90%. Understanding the presence and characteristics of hydrated OM is expected to engage important future research in several sciences and in geotechnical engineering of terrestrial and marine mud deposits.