ICHNOFABRIC CHAR AC TER IZA TION IN CORES: A METHOD OF DIG I TAL IM AGE TREAT MENT

Ab stract: Ichnofabric anal y sis, as a rel a tively young ichnological ap proach, has wit nessed rapid growth, show ing its use ful ness in ba sin anal y sis, with spe cial at ten tion to palaeoenvironmental in ter pre ta tions. The ichnofabric ap proach has evolved from the de scrip tion of trace com po si tion and the in ten sity of bioturbation to in te grate de tailed in for ma tion on nu mer ous ichnofabric fea tures, such as pri mary sed i men tary struc tures, ichnological di ver sity, ichnological fea tures, cross-cut ting re la tion ships or tier ing struc tures. This de vel op ment has been as so ci ated with its ap pli ca tion to the study of deep-sea sed i ments, es pe cially in re search on cores, which is not easy, ow ing to the par tic u lar fea tures of cores. Here a method for im prov ing ichnofabric char ac ter iza tion in mod ern ma rine cores is pre sented, on the ba sis of dig i tal high-res o lu tion im age treat ment, with spe cial em pha sis on the quan ti fi ca tion of ichnofabric at trib utes. The pro posed meth od ol ogy is based on the mod i fi ca tion of three im age ad just ments (im age ad just ment), the es ti ma tion of the per cent age of the area oc cu pied by bioturbation (dig i tal es ti ma tion), the lat eral and ver ti cal quan ti fi ca tion and com par i son of pixel val ues for the infill of the trace fos sils and the host sed i ment (pixel count ing), and the in te gra tion of the in for ma tion ob tained in the vi sual rep re sen ta tions of ichnofabrics (the ichnofabric rep re sen ta tion). The se quen tial ap pli ca tion of these pro posed steps al low, 1) better iden ti fi ca tion of trace fos sils, to gether with cross-cut ting re la tion ships and the char ac ter iza tion of trace-fos sil as sem blages, 2) es ti ma tion of the per cent age of bioturbation as so ci ated to each ichnotaxon, the whole ichnocoenosis, or a com plete ichnofabric, 3) dif fer en ti a tion be tween biodeformational struc tures and trace fos sils, dis crim i na tion be tween ichnotaxa, dis tinc tion be tween pas sively and ac tively infilled struc tures, and 4) eval u a tion of the depth of pen e tra tion by par tic u lar tracemakers.