Exogenous rocks

Boggs, K., Rock, C.O., and Jackowski, S., 1998, The antiproliferative effect of hexadecyl-phosphochohne toward HL60 cells is prevented by exogenous lysophosphatidylchohne. Biochim. Biophys. Acta, 1389 1-12... 

Because sedimentary carbonates represent primarily chemical and biochemical precipitates from seawater, and because they make up 20% of the common sedimentary rock record, these rock types have been particularly good sources of chemical and mineralogical data for interpretation of the secular and cyclic evolution of the Earth s surface environment. This carbonate rock record as a function of geological age is now explored as are age trends in other rock types and sediment properties. With this information as background material, we can then discuss what these relationships tell us about the history of carbonates and the exogenic system throughout geologic dme. 

Study of specific regions in which iron cherts and volcanic rocks are spatially unconnected naturally led to the development of hypotheses of an exogene source of the iron, unrelated to volcanism. Thus there arose the hypothesis that the iron cherts were formed from material supplied to the sedimentary basin in the course of intensive subaerial weathering. Svital skiy (1924), Piatnitskiy (1924), Strakhov (1947), James (1954), White (1954), Belevtsev (1957) and Plaksenko (1966) shared this hypothesis. 

The lithosphere, hydrosphere, atmosphere, and biosphere, or rocks, water, air, and life are all part of the terrestrial exogenic system that is definable by the rules and approaches of general system science theory, with its subsets, such as population dynamics and hierarchical structures. 

The two dominant exogenic reservoirs of carbon are carbonate rocks and organic matter in sediments. They are linked in the carbon cycle via atmospheric CO2 and the carbon species dissolved in the hydrosphere. The for the total... 

Sigal L, Crotty IS, Andino R, Rock KL (1999) Cytotoxic T-cell immuiuty to virus-infected non-haematopoietic cells requires presentation of exogenous antigen. Nature 398 77-80. 

Rock, K.L., Rothstein, L., Fleishacker, C. and Gamble, S. (1992). Inhibition of class I and class II MHC-restricted antigen presentation by cytotoxic T lymphocytes specific for an exogenous antigen. J. Immunol. 148, 3028-3033. 

Figure 1. The exogenic and endogenic cycles showing interchanges of matter between the biosphere, oceans, atmosphere and geological rocks. These features are usual in the biogeochemical cycles of different elements (from Engel and Macko, 1993).

It is remarkable, that only after the endogene alteration processes had finished, the rock has been exposed to the exogene processes of weathering. The change of mineral content and the increase of... 

Source Adapted from Navert H, Rock EV, Tyce GW, et al. Metabolism of exogenous histamine-during gastric secretion in dogs. Am J Physiol 217 1823-1829,1969. 

Chemical equilibrium and mass transfer mechanisms (chemical reactions, diffusion, fluid flow (advection), adsorption, etc.) (Chaps. 1,2, and 3) are examined in order to illustrate the compositional variation that exists within water (ground water, hydrothermal solution, seawater) and weathered and hydrothermally altered rocks and soils. To better understand the subsystems of the earth, equilibrium and mass transfer coupling models are apphed to the seawater system, as an example of a low-temperature exogenic system, and hydrothermal systems, as an example of high-temperature endogenic systems (Chap. 4). 

The flow of matter from continents to oceans and to the ocean floor is obviously visible it is frequently termed exogenous or minor cycle . It describes the transfer of matter from the lithosphere to the hydrosphere and then back to the lithosphere. It is questionable whether a fragment of weathered rock, either crystalline or sedimentary in origin, moving in streams is part of the lithosphere. 

Sea. Randama and Sahama [12] suggest that sediments and sedimentary rocks of marine origin should contain more arsenic than igneous rocks do, because large amounts of arsenic have been introduced directly into the exogenic cycle by volcanic activity. 

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