Rhymites are indicator of sea level change, tides, glaciation and change in paleoclimatology. Does salinity play role to form tidal rhymites?
No!
Rhymites are the result of physical changes such as tides. Salinity is a chemical effect and cannot produce rymites.
Dear Dr. Saha,
Tidal rhythmites sensu stricto occurring in what is called the intertidal zone result from periodical physical processes of alternating ebb and flood and first and foremost are not affected by salinity variations. The tidal environment can roughly be subdivided into three zones, sub-, intra- and suprtidal. Considering the Ca sulfate system represented by gypsum and anhydrite may provide a different picture for the subtidal (basinal) and supratidal (sabkha) zones, where near the coast in combination with OM (algal growth), carbonate minerals such as huntite and particular clay minerals of the hormite group (palygorskite) a crude rhythmic lamination can be observed . In the latter zone the salinity changes can easily be recognized by the ubiquitous but variable accumulation of halite cubes. It is a function of the lateral facies changes which have a control on the fine-tuning of the salinity and last-but-not least the presence or absence of laminated or rhythmic sedimentary sequences.
H.G.Dill
Dear Sir (Professor Dr. H. G. Dill),
Good morning. Your detailed explanation helped me a lot to comprehend the formation of tidal rhythmites. Thanks a lot Sir.
Sincerely yours,
Sudip Saha
Alastair Bain McDonald To separate physical from chemical processes in the tidal zone seems dubious. Surely, in certain environments, tides can change salinity on the diurnal or semidiurnal period. Think of either estuaries or hypersaline lagoons - in either case the tide will change the salinity (rising tide raising salinity in estuaries and lowering salinity in hypersaline lagoons).
However, after addressing that (I couldn't keep my nose out of that response), I thought I would pose the question of whether there is a difference between rhymites and rhythmites. Is there a good text or manuscript detailing differences, or is this just a slow change in our vernacular as geologists?
Brad E. Rosenheim ,
Rhythmites formed by diurnal tides would, IMHO, have difficulty in retaining any chemical characteristics as the following tide would dissolve away the effects of the previous tide. Of course, seasonally formed evaporites might produce annual rhythmites. Of course the proof is in the pudding - does anyone know of saline rhythmites?
There are some texts here describing rhythmites. I think rhymites is just a misspelling.
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/rhythmite
I completely agree with Dr. Alastair Bain McDonald. The subsequent tide, monsoon floods can wash away the dissolved materials that deposited in the rhythmites from the previous tides.
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