Bir Dağın Baş Döndürücü Yolculuğu: Aziz Martha’nın Karlı Sıradağları

Avrupa ve Amerika’nın çeşitli üniversitelerinden araştırmacılar dört yıllık ortak bir çalışma ile Sierra Nevada de Santa Marta (Aziz Martha Karlı Sıradağları) jeolojik (yerbilimsel) evrimini araştırıyorlar. ABD Smithsonian Enstitüsü’nün bir ayağı olan ve Panama’da yer alan Smithsonian Tropikal Araştırmalar Enstitüsü (STRI) araştırmacıları da bu projede yer alıyor. STRI araştırmacıları bu ay yayımladıkları bir makaleyle Kolombiya’nın Karayip sahillerinde bulunan Santa Marta’nın buraya Peru’dan geldiğini açıkladılar.

Çalışma, dağın taşlarından (ya da jeolojik jargona göre kayaçlarından) yola çıkarak oldukça ilgi çekici bir hikâye ortaya koyuyor: Süper-kıtalarla çarpışma ve ayrılma. Volkanların (yanardağların) doğuşu ve ölüşü. Peru’dan başlayıp kuzey Kolombiya’ya ulaşarak saat yönünde yapılan bir dönüş ile şimdi bulunduğu yere ulaşma ve yepyeni bir jeolojik havzanın açılışı.

Yürütülen araştırmalarda jeolojik, yapısal, paleomanyetik, jeokimyasal ve jeokronolojik alanlardaki en son tekniklerin kullanıldığı belirtiliyor. Bu uluslararası bilimsel projede yer alan bilim insanları, çalışmalarıyla bölgenin jeolojisine (yerbilimine) dair bilgilerimizdeki boşlukların tamamladığına işaret ediyorlar.

Santa Marta’nın farklı türlerdeki taşların kökenlerinin 1 milyar yıldan daha önceye gittiğini anlatan araştırmacılar, çalışmalardan birisinde bu taşlarla Güney Amerika’daki sıra dağların kökenleri arasında ilişki kurulduğunu belirtiyorlar. STRI araştırmacıları, bu taşlardaki manyetik alan izlerini inceleyerek Santa Marta’nın Peru’nun kuzeyinden başlayıp Kolombiya’nın Karayip sahillerine kadar uzanan 2200 km ve 170 milyon yıllık seyahatini ortaya koyuyorlar.


Sierra Nevada de Santa Marta, Colombia – January 1990
The highest coastal mountain range in the world, the Sierra Nevada de Santa Marta is visible in this east-southeast-looking view. The Sierra Nevada de Santa Marta includes several climatic zones across a strip only 25 miles (40 km) from the sea. These zones include a tropical climate at the coast to a perpetual snow line above 16,000 feet (4880 meters) and a cold Alpine climate. The two highest peaks in the Santa Marta Range are Cristobal Colon Peak (named after Christopher Colombus) 19029 feet (5800 meters) and Simon Bolivar Peak (named after the famous South American liberator) 18947 feet (5775 meters). Small glacier fields at the top of the range cover an area of 6 sq. miles (16 sq. km). The Sierra Nevada de Santa Marta serves as the source of 36 streams and rivers. To the west of the Santa Marta Range just to the right of the bottom center of the image, is a swamp-like feature, the Cienaga Grande. To the left of the Cienaga Grande swamps near the bottom center of the scene is the city of Santa Marta, the oldest city of European origin in South America. Image: Image Science and Analysis Laboratory, NASA-Johnson Space Center

Earth’s Highest Coastal Mountain on the Move
The rocks of Colombia’s Sierra Nevada de Santa Marta—the highest coastal mountain on Earth—tell a fascinating tale: The mountain collides and then separates from former super-continents. Volcanoes are born and die. The mountain travels from Peru to northern Colombia and finally rotates in a clockwise direction to open up an entirely new geological basin. Smithsonian scientists were part of a four-year project researching Santa Marta’s geological evolution. Their findings are published in the October 2010 special issue of the Journal of South American Earth Sciences.

The study involved state-of-the-art geological, structural, paleomagnetic, geochemical and geochronological techniques applied by collaborators from universities and research institutions in several European countries and the Americas. “This integrated study represents a long-awaited contribution—particularly to the international scientific community who work in the circum-Caribbean—and fills a notorious gap in the picture of the region’s geology,” said Agustin Cardona, postdoctoral fellow at the Smithsonian Tropical Research Institute.

The diverse rock record exposed in Santa Marta rests on an ancient foundation that is more than 1 billion years old. One of the studies links the foundation to other old massifs in the Americas. Using the ancient magnetic field recorded in these rocks, the Smithsonian research group revealed Santa Marta’s 2,200-kilometer journey from northern Peru to its modern position on the Caribbean coast of Colombia during the past 170 million years.

Sophisticated laboratory analyses of Santa Marta rock samples also offered scientists an explanation of their origin as remnants of extinct volcanoes and mountains that once existed but were later obliterated by powerful geologic forces.

Other studies revealed observations pertaining to recent dislocations along the Sierra’s bounding faults—evidence of historic earthquakes and a large submarine canyon carved in the floor of the Caribbean Sea. “We hope that this contribution will serve as a catalyst to accelerate the pace of geological research along this margin of South America,” said German Ojeda, co-leader of the research team and geologist at Colombia’s Ecopetrol energy company. Sponsoring agencies included the geological and marine science research institutes of the Colombian government.

STRI, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.

Kaynakça
Hanoğlu, Ö. Dağlar da Seyahat Eder, Güncel Haber ve Yazılar, TÜBİTAK, 4 Nisan 2011 tarihinde ulaşılmıştır.
King, B., and Alvarado, M., 2011. Earth’s Highest Coastal Mountain on the Move, News Releases, STRI, accessed at April 4th 2011.