Econ. Environ. Geol. 2014; 47(1): 1-15

Published online February 28, 2014

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

The Occurrence and Origin of a Syn-collisional M?lange in Timor

Seung-Ik Park1,2*, Hee Jae Koh1, Sung Won Kim1 and You Hong Kihm1

1Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Republic of Korea
2Department of Earth System Sciences, Yonsei University, Seoul 120-749, Republic of Korea

Correspondence to : sipark@kigam.re.kr

Received: October 7, 2013; Revised: December 1, 2013; Accepted: December 26, 2013

Abstract

  The Bobonaro m?lange is one of the youngest syn-collisional m?langes, located between the Indo-Australian and Eurasian plates. The m?lange has formed in association with a collision between the Australian continental margin and the Banda arc initiated in Neogene. The Suai area at the southern part of Timor is a good place to examine the genetic relationship between the m?lange and other rock sequences because various tectonostratigraphic units coexist in the area. In this study, we present the structural characteristics and spatial distribution of the Bobonaro m?lange investigated as a part of 1:25K scale geologic mapping in the area, and discuss on the origin of the m?lange. The Bobonaro m?lange in the Suai area is composed of unmetamorphosed clay matrix and blocks of various lithologies. The clay matrix mainly is reddish brown or greenish gray in colour, and has scaly texture. Most blocks are allochthonous, but mostly derived from nearby formations. Based on the internal structure and relationship with surrounding rocks, the Bobonaro m?lange is genetically classified into 1) diapiric m?lange; 2) tectonic m?lange; and 3) broken formation. The spatial distribution of the Bobonaro m?lange indicates that it intruded all pre-collisional units including the lower Australian continental margin unit(Gondwana megasequence) and the Banda arc unit. Taking the field evidences and previous genetic models into consideration, the Bobonaro m?lange is interpreted to be mainly formed as a diapiric m?lange originated from Gondwana megasequence, consistently effected by faulting events. This study reflects that diapiric m?lange is a significant component in recent accretionay- collision belts. It suggests that diapiric process should be considered as a main genetic factor even in ancient m?lange.

Keywords arc-continent collision, Timor, Bobonaro m?lange, diapiric m?lange

Article

Econ. Environ. Geol. 2014; 47(1): 1-15

Published online February 28, 2014

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

The Occurrence and Origin of a Syn-collisional M?lange in Timor

Seung-Ik Park1,2*, Hee Jae Koh1, Sung Won Kim1 and You Hong Kihm1

1Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Republic of Korea
2Department of Earth System Sciences, Yonsei University, Seoul 120-749, Republic of Korea

Correspondence to:sipark@kigam.re.kr

Received: October 7, 2013; Revised: December 1, 2013; Accepted: December 26, 2013

Abstract

  The Bobonaro m?lange is one of the youngest syn-collisional m?langes, located between the Indo-Australian and Eurasian plates. The m?lange has formed in association with a collision between the Australian continental margin and the Banda arc initiated in Neogene. The Suai area at the southern part of Timor is a good place to examine the genetic relationship between the m?lange and other rock sequences because various tectonostratigraphic units coexist in the area. In this study, we present the structural characteristics and spatial distribution of the Bobonaro m?lange investigated as a part of 1:25K scale geologic mapping in the area, and discuss on the origin of the m?lange. The Bobonaro m?lange in the Suai area is composed of unmetamorphosed clay matrix and blocks of various lithologies. The clay matrix mainly is reddish brown or greenish gray in colour, and has scaly texture. Most blocks are allochthonous, but mostly derived from nearby formations. Based on the internal structure and relationship with surrounding rocks, the Bobonaro m?lange is genetically classified into 1) diapiric m?lange; 2) tectonic m?lange; and 3) broken formation. The spatial distribution of the Bobonaro m?lange indicates that it intruded all pre-collisional units including the lower Australian continental margin unit(Gondwana megasequence) and the Banda arc unit. Taking the field evidences and previous genetic models into consideration, the Bobonaro m?lange is interpreted to be mainly formed as a diapiric m?lange originated from Gondwana megasequence, consistently effected by faulting events. This study reflects that diapiric m?lange is a significant component in recent accretionay- collision belts. It suggests that diapiric process should be considered as a main genetic factor even in ancient m?lange.

Keywords arc-continent collision, Timor, Bobonaro m?lange, diapiric m?lange

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

    Stats or Metrics

    Share this article on

    • kakao talk
    • line

    Economic and Environmental Geology

    pISSN 1225-7281
    eISSN 2288-7962
    qr-code Download