Tectonic Connection Research Articles

Evidence of interconnection between seismic activity in the Iberian Peninsula and North African belts

Abstract The seismicity patterns of the North African deformation belts and Iberian Peninsula show a close time correspondence. The high statistical significance of this interrelation, estimated using different techniques, suggests the presence of a tectonic connection between these regions.

Northern Hemisphere climate régimes during the past 3 Ma: possible tectonic connections

The 100 ka rhythm of orbital eccentricity has dominated large-amplitude climatic variations in the high-latitude North Atlantic during the Brunhes magnetic chron (0-0.735 Ma BP ). Earlier, during the Matuyama chron (0.735-2.47 Ma BP), climatic variations in this region were lower in amplitude and concentrated mainly at the 41 ka rhythm of orbital obliquity. These rhythmic climatic responses to orbital forcing are evident both in stable isotopic (δ 18 O) indicators of ice volume or temperature and in biotic and lithologic indicators of local North Atlantic surface-ocean variability. The synchronous responses of these indicators are consistent with results from atmospheric general circulation models showing that the North American ice sheet directly controls North Atlantic surface-ocean responses via strong cold winds that are generated on the northern ice-sheet flanks and blow out across the ocean, chilling its surface. Before 2.47 Ma BP , smaller-scale quasiperiodic oscillations of the planktonic fauna and flora occurred, but the cause of these variations in the absence of significant ice sheets is unclear.

Evidence of interrelation between the seismicity of the Southern Apennines and Southern Dinarides

During the last two centuries the strongest earthquakes in the Southern Apennines ( M > 5.5) have almost regularly occurred within a short time (a few months to some years) of the occurrence of earthquakes in Southern Yugoslavia. The high statistical significance of this correspondence suggests the presence of a tectonic connection between the two zones.

Late Paleozoic Clastic Wedges in Appalachian Province: ABSTRACT

Late Paleozoic clastic wedges, arrayed from north to south along the western edge of the Appalachian tectonic welt, differ in age as well as spatial relations. The northern, Catskill, wedge is the oldest and apparently was derived from the north, whereas the succeeding Warrior-Arkoma wedge was apparently derived from a southern or Ouachita source. The youngest, Pocahontas and Dunkard, wedges are located between the older two and were derived from only a relatively small area in the central Appalachian Blue Ridge and Piedmont. Although the style of sedimentation differs among these large sedimentary prisms, all were governed by similar tectonic controls of differential subsidence and growth faulting. Significantly, the trend of tectonic complexes from which the sediments w re derived is nearly at right angles to most of the present structures and suggests predrift tectonic connection. End_of_Article - Last_Page 778------------

Tectonic effects of sea-floor spreading on the Arabian Shield

Paleogeographic evidence shows that the series of broad E-W anticlines and synclines on the Arabian Shield (Southern Hadramawt Arch, Wadi Hadramawt Syncline, Northern Hadramawt Arch, Rub Al Khali Syncline, Tuwaiq Homocline, Nafud Basin) are not old, inherited structures, but were formed in late Eocene and Oligocene times, as indicated by the warping of Middle Eocene sediments. The fold axes of these structures trend parallel to the Gulf of Aden, and their separation increases from S to N, i. e., with increasing distance from the Gulf of Aden. The most pronounced orogenic phase of the Toros mountain belt and the folding of the foreland belt (Lebanon, Antilebanon, Palmyra Arch, Jebel Sinjar, etc.) took place simultaneously with the warping of the shield. Furthermore, the early Tertiary “Trap” Volcanism occurs only in the neighborhood of the Gulf of Aden (Yemen, W-Aden Protectorate, Eritrea, Ethiopia, Somaliland). Geophysical-oceanographic research in the Gulf of Aden suggests that emplacement of basic magmatic material forms a quasi-oceanic crust (sea-floor spreading) in that rift trough. This apparently causes the displacement of the continental blocks. The close connections in time as well as in directional trends of epirogenic, orogenic and volcanic activities on the Arabian Shield to the sea-floor spreading in the Gulf of Aden indicates tectonic interrelations.This impression is still emphasized, if one considers the younger tectonic development on the shield. The young Tertiary “Aden”-Volcanics Belt (Miocene-Recent) extends from the East African Rift system over the West Arabian Shield all the way up to Turkey, that is to say its trend is more or less parallel to the Red Sea. Warping effects (Ras en Naqb Uplift, Jafr Depression, Bayir Uplift, Wadi Sirhan Depression, Rutba Dome and the Mesopotanian Basin) on the northern part of the Arabian Shield, where the earlier developed (Aden Gulf-related) structures die out, can be related in time and direction to the rifting in the Red Sea. Faulting along the Aqaba-Dead Sea System is of the same age and cuts the foreland belt. Finally the folding of the Zagros mountain belt is of Miocene age too.The Arabian Shield, bounded by still-active rifting structures of different direction and age, provides a classical example of the effect of sea-floor spreading on a shield area itself, and on its surrounding instable belt. The correct interpretation of these tectonic connections eventually may allow far reaching, basic conclusions.