Month: September 2022

Midnight chimes on New Year’s eve on the steps of the imposing Girona cathedral, and crowds repeat what has been a 2,000 year old tradition. View in LinkedIn

Hubble Revisits the Veil Nebula https://lnkd.in/dAAK_yED View in LinkedIn

ORIGIN OF MAGNETIC SHIELD. “Earth's internal strong dipolar magnetic field may have developed in its present form only about 600 m.y. ago after a long hiatus without such a field or with one that was much weaker or more complicated.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

ONE SAMPLED DATA SOURCE. “Testing, which I do not attempt, is desirable to confirm or reject that hypothesis. Purported Archean paleomagnetic data are so sparse in time and space, the dating of remnant magnetization so ambiguous and orientations so scattered, as to presently add little to the debate. There are, however, many hundreds of purported determinations of magnetic orientations of Proterozoic rocks.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

SELECTIVE DATA FITTING. “Nevertheless, there are few relevant dates and selective use of those ambiguous data to fit conflicting models has impeded progress. Buchan (2013) saw only a single continent (northern North America + Greenland) as usefully constrained during the Proterozoic.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

PLATE ASSUMPTIONS. “Some investigators infer intricate aggregations and sunderings much more chaotic than modern plate behavior of hypothetical supercontinents Columbia and Rodinia (Fig. 32a) found little change from 1000 to 750 m.y. ago but rationalized that plate activity occurred during that era without differential motions.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

PREVAILING DOGMA. “Piper (2018) illustrated a little-varying Proterozoic supercontinent (Fig. 32b) whose core aggregate was fixed in Proterozoic latitude (which is incompatible with the geodetic expectation that the spin equator be parallel, not perpendicular, to megacontinent/megaocean dichotomy boundary) until it sundered when modern plate tectonics began in the very late Proterozoic.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

GROUP THINK OF THE ERA. “These are only a few examples of the many that exist. Possibly relevant is the observation that all of these aggregates share similar features and so there may have been little or no dispersal or aggregation until latest Proterozoic time (Meert, 2014).” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

POSSIBLE SALVAGE. “Phanerozoic remagnetization of Precambrian rocks? The study of the large paleomagnetic database for Precambrian and Phanerozoic rocks of Europe east of Britain and the Carpathians by Bazhenov et al. (2016) provides a possible avenue for solving the conflicts.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn

THE HYPOTHESIS. “This is because purported Precambrian magnetic poles in that region apparently record Phanerozoic magnetization of Precambrian rocks. Earth's strong dipolar internally generated magnetic field may have originated only about 600 m.y. ago.” https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub View in LinkedIn